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2021-03-24 00:31:08 +00:00
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<a href='https://github.com/akkartik/mu/blob/main/boot.subx'>https://github.com/akkartik/mu/blob/main/boot.subx</a>
<pre id='vimCodeElement'>
<span id="L1" class="LineNr"> 1 </span><span class="subxComment"># Code for the first few disk sectors that all programs in this directory need:</span>
<span id="L2" class="LineNr"> 2 </span><span class="subxComment"># - load sectors past the first (using BIOS primitives) since only the first is available by default</span>
<span id="L3" class="LineNr"> 3 </span><span class="subxComment"># - if this fails, print 'D' at top-left of screen and halt</span>
<span id="L4" class="LineNr"> 4 </span><span class="subxComment"># - initialize a minimal graphics mode</span>
<span id="L5" class="LineNr"> 5 </span><span class="subxComment"># - switch to 32-bit mode (giving up access to BIOS primitives)</span>
<span id="L6" class="LineNr"> 6 </span><span class="subxComment"># - set up a handler for keyboard events</span>
<span id="L7" class="LineNr"> 7 </span><span class="subxComment"># - jump to start of program</span>
<span id="L8" class="LineNr"> 8 </span>
<span id="L9" class="LineNr"> 9 </span><span class="subxComment"># Code in this file needs to be more deliberate about the SubX facilities it</span>
<span id="L10" class="LineNr"> 10 </span><span class="subxComment"># uses:</span>
<span id="L11" class="LineNr"> 11 </span><span class="subxComment"># - sigils only support 32-bit general-purpose registers, so don't work with segment registers or 16-bit or 8-bit registers</span>
<span id="L12" class="LineNr"> 12 </span><span class="subxComment"># - metadata like rm32 and r32 can sometimes misleadingly refer to only the bottom 16 bits of the register; pay attention to the register name</span>
<span id="L13" class="LineNr"> 13 </span>
<span id="L14" class="LineNr"> 14 </span><span class="subxComment"># Memory map of a Mu computer:</span>
<span id="L15" class="LineNr"> 15 </span><span class="subxComment"># code: 4 tracks of disk to [0x00007c00, 0x00027400)</span>
<span id="L16" class="LineNr"> 16 </span><span class="subxComment"># stack grows down from 0x00070000</span>
<span id="L17" class="LineNr"> 17 </span><span class="subxComment"># see below</span>
<span id="L18" class="LineNr"> 18 </span><span class="subxComment"># heap: [0x01000000, 0x02000000)</span>
<span id="L19" class="LineNr"> 19 </span><span class="subxComment"># see 120allocate.subx</span>
<span id="L20" class="LineNr"> 20 </span><span class="subxComment"># Consult <a href="https://wiki.osdev.org/Memory_Map_(x86)">https://wiki.osdev.org/Memory_Map_(x86)</a> before modifying any of this.</span>
<span id="L21" class="LineNr"> 21 </span>
<span id="L22" class="LineNr"> 22 </span>== code
<span id="L23" class="LineNr"> 23 </span>
<span id="L24" class="LineNr"> 24 </span><span class="subxComment">## 16-bit entry point: 0x7c00</span>
<span id="L25" class="LineNr"> 25 </span>
<span id="L26" class="LineNr"> 26 </span><span class="subxComment"># Upon reset, the IBM PC:</span>
<span id="L27" class="LineNr"> 27 </span><span class="subxComment"># - loads the first sector (512 bytes)</span>
<span id="L28" class="LineNr"> 28 </span><span class="subxComment"># from some bootable image (look for the boot-sector-marker further down this file)</span>
<span id="L29" class="LineNr"> 29 </span><span class="subxComment"># to the address range [0x7c00, 0x7e00)</span>
<span id="L30" class="LineNr"> 30 </span><span class="subxComment"># - starts executing code at address 0x7c00</span>
<span id="L31" class="LineNr"> 31 </span>
<span id="L32" class="LineNr"> 32 </span> fa/disable-interrupts
<span id="L33" class="LineNr"> 33 </span>
<span id="L34" class="LineNr"> 34 </span> <span class="subxComment"># initialize segment registers</span>
<span id="L35" class="LineNr"> 35 </span> b8/copy-to-ax 0/imm16
<span id="L36" class="LineNr"> 36 </span> 8e/-&gt;seg 3/mod/direct 0/rm32/ax 3/r32/ds
<span id="L37" class="LineNr"> 37 </span> 8e/-&gt;seg 3/mod/direct 0/rm32/ax 0/r32/es
<span id="L38" class="LineNr"> 38 </span> 8e/-&gt;seg 3/mod/direct 0/rm32/ax 4/r32/fs
<span id="L39" class="LineNr"> 39 </span> 8e/-&gt;seg 3/mod/direct 0/rm32/ax 5/r32/gs
<span id="L40" class="LineNr"> 40 </span>
<span id="L41" class="LineNr"> 41 </span> <span class="subxComment"># initialize stack to 0x00070000</span>
<span id="L42" class="LineNr"> 42 </span> <span class="subxComment"># We don't read or write the stack before we get to 32-bit mode, but BIOS</span>
<span id="L43" class="LineNr"> 43 </span> <span class="subxComment"># calls do. We need to move the stack in case BIOS initializes it to some</span>
<span id="L44" class="LineNr"> 44 </span> <span class="subxComment"># low address that we want to write code into.</span>
<span id="L45" class="LineNr"> 45 </span> b8/copy-to-ax 0x7000/imm16
<span id="L46" class="LineNr"> 46 </span> 8e/-&gt;seg 3/mod/direct 0/rm32/ax 2/r32/ss
<span id="L47" class="LineNr"> 47 </span> bc/copy-to-esp 0/imm16
<span id="L48" class="LineNr"> 48 </span>
<span id="L49" class="LineNr"> 49 </span> <span class="subxComment"># undo the A20 hack: <a href="https://en.wikipedia.org/wiki/A20_line">https://en.wikipedia.org/wiki/A20_line</a></span>
<span id="L50" class="LineNr"> 50 </span> <span class="subxComment"># this is from <a href="https://github.com/mit-pdos/xv6-public/blob/master/bootasm.S">https://github.com/mit-pdos/xv6-public/blob/master/bootasm.S</a></span>
<span id="L51" class="LineNr"> 51 </span> {
<span id="L52" class="LineNr"> 52 </span> e4/read-port-into-al 0x64/imm8
<span id="L53" class="LineNr"> 53 </span> a8/test-bits-in-al 0x02/imm8 <span class="subxComment"># set zf if bit 1 (second-least significant) is not set</span>
<span id="L54" class="LineNr"> 54 </span> 75/jump-if-!zero <span class="Constant">loop</span>/imm8
<span id="L55" class="LineNr"> 55 </span> b0/copy-to-al 0xd1/imm8
<span id="L56" class="LineNr"> 56 </span> e6/write-al-into-port 0x64/imm8
<span id="L57" class="LineNr"> 57 </span> }
<span id="L58" class="LineNr"> 58 </span> {
<span id="L59" class="LineNr"> 59 </span> e4/read-port-into-al 0x64/imm8
<span id="L60" class="LineNr"> 60 </span> a8/test-bits-in-al 0x02/imm8 <span class="subxComment"># set zf if bit 1 (second-least significant) is not set</span>
<span id="L61" class="LineNr"> 61 </span> 75/jump-if-!zero <span class="Constant">loop</span>/imm8
<span id="L62" class="LineNr"> 62 </span> b0/copy-to-al 0xdf/imm8
<span id="L63" class="LineNr"> 63 </span> e6/write-al-into-port 0x64/imm8
<span id="L64" class="LineNr"> 64 </span> }
<span id="L65" class="LineNr"> 65 </span>
<span id="L66" class="LineNr"> 66 </span> <span class="subxComment"># load remaining sectors from first two tracks of disk into addresses [0x7e00, 0x17800)</span>
<span id="L67" class="LineNr"> 67 </span> b4/copy-to-ah 2/imm8/read-drive
<span id="L68" class="LineNr"> 68 </span> <span class="subxComment"># dl comes conveniently initialized at boot time with the index of the device being booted</span>
<span id="L69" class="LineNr"> 69 </span> b5/copy-to-ch 0/imm8/cylinder
<span id="L70" class="LineNr"> 70 </span> b6/copy-to-dh 0/imm8/head
<span id="L71" class="LineNr"> 71 </span> b1/copy-to-cl 2/imm8/sector <span class="subxComment"># 1-based</span>
<span id="L72" class="LineNr"> 72 </span> b0/copy-to-al 0x7d/imm8/num-sectors <span class="subxComment"># 2*63 - 1 = 125</span>
<span id="L73" class="LineNr"> 73 </span> <span class="subxComment"># address to write sectors to = es:bx = 0x7e00, contiguous with boot segment</span>
<span id="L74" class="LineNr"> 74 </span> bb/copy-to-bx 0/imm16
<span id="L75" class="LineNr"> 75 </span> 8e/-&gt;seg 3/mod/direct 3/rm32/bx 0/r32/es
<span id="L76" class="LineNr"> 76 </span> bb/copy-to-bx 0x7e00/imm16
<span id="L77" class="LineNr"> 77 </span> cd/syscall 0x13/imm8/bios-disk-services
<span id="L78" class="LineNr"> 78 </span> 0f 82/jump-if-carry <a href='boot.subx.html#L144'>disk_error</a>/disp16
<span id="L79" class="LineNr"> 79 </span>
<span id="L80" class="LineNr"> 80 </span> <span class="subxComment"># load two more tracks of disk into addresses [0x17800, 0x27400)</span>
<span id="L81" class="LineNr"> 81 </span> b4/copy-to-ah 2/imm8/read-drive
<span id="L82" class="LineNr"> 82 </span> <span class="subxComment"># dl comes conveniently initialized at boot time with the index of the device being booted</span>
<span id="L83" class="LineNr"> 83 </span> b5/copy-to-ch 0/imm8/cylinder
<span id="L84" class="LineNr"> 84 </span> b6/copy-to-dh 2/imm8/head
<span id="L85" class="LineNr"> 85 </span> b1/copy-to-cl 1/imm8/sector <span class="subxComment"># 1-based</span>
<span id="L86" class="LineNr"> 86 </span> b0/copy-to-al 0x7e/imm8/num-sectors <span class="subxComment"># 2*63 = 126</span>
<span id="L87" class="LineNr"> 87 </span> <span class="subxComment"># address to write sectors to = es:bx = 0x17800, contiguous with boot segment</span>
<span id="L88" class="LineNr"> 88 </span> bb/copy-to-bx 0x1780/imm16
<span id="L89" class="LineNr"> 89 </span> 8e/-&gt;seg 3/mod/direct 3/rm32/bx 0/r32/es
<span id="L90" class="LineNr"> 90 </span> bb/copy-to-bx 0/imm16
<span id="L91" class="LineNr"> 91 </span> cd/syscall 0x13/imm8/bios-disk-services
<span id="L92" class="LineNr"> 92 </span> 0f 82/jump-if-carry <a href='boot.subx.html#L144'>disk_error</a>/disp16
<span id="L93" class="LineNr"> 93 </span>
<span id="L94" class="LineNr"> 94 </span> <span class="subxComment"># load two more tracks of disk into addresses [0x27400, 0x37000)</span>
<span id="L95" class="LineNr"> 95 </span> b4/copy-to-ah 2/imm8/read-drive
<span id="L96" class="LineNr"> 96 </span> <span class="subxComment"># dl comes conveniently initialized at boot time with the index of the device being booted</span>
<span id="L97" class="LineNr"> 97 </span> b5/copy-to-ch 0/imm8/cylinder
<span id="L98" class="LineNr"> 98 </span> b6/copy-to-dh 4/imm8/head
<span id="L99" class="LineNr"> 99 </span> b1/copy-to-cl 1/imm8/sector <span class="subxComment"># 1-based</span>
<span id="L100" class="LineNr"> 100 </span> b0/copy-to-al 0x7e/imm8/num-sectors <span class="subxComment"># 2*63 = 126</span>
<span id="L101" class="LineNr"> 101 </span> <span class="subxComment"># address to write sectors to = es:bx = 0x27400, contiguous with boot segment</span>
<span id="L102" class="LineNr"> 102 </span> bb/copy-to-bx 0x2740/imm16
<span id="L103" class="LineNr"> 103 </span> 8e/-&gt;seg 3/mod/direct 3/rm32/bx 0/r32/es
<span id="L104" class="LineNr"> 104 </span> bb/copy-to-bx 0/imm16
<span id="L105" class="LineNr"> 105 </span> cd/syscall 0x13/imm8/bios-disk-services
<span id="L106" class="LineNr"> 106 </span> 0f 82/jump-if-carry <a href='boot.subx.html#L144'>disk_error</a>/disp16
<span id="L107" class="LineNr"> 107 </span>
<span id="L108" class="LineNr"> 108 </span> <span class="subxComment"># reset es</span>
<span id="L109" class="LineNr"> 109 </span> bb/copy-to-bx 0/imm16
<span id="L110" class="LineNr"> 110 </span> 8e/-&gt;seg 3/mod/direct 3/rm32/bx 0/r32/es
<span id="L111" class="LineNr"> 111 </span>
<span id="L112" class="LineNr"> 112 </span> <span class="subxComment"># adjust video mode</span>
<span id="L113" class="LineNr"> 113 </span> b4/copy-to-ah 0x4f/imm8 <span class="subxComment"># VBE commands</span>
<span id="L114" class="LineNr"> 114 </span> b0/copy-to-al 2/imm8 <span class="subxComment"># set video mode</span>
<span id="L115" class="LineNr"> 115 </span> bb/copy-to-bx 0x4105/imm16 <span class="subxComment"># 0x0105 | 0x4000</span>
<span id="L116" class="LineNr"> 116 </span> <span class="subxComment"># 0x0105 = graphics mode 1024x768x256</span>
<span id="L117" class="LineNr"> 117 </span> <span class="subxComment"># (alternative candidate: 0x0101 for 640x480x256)</span>
<span id="L118" class="LineNr"> 118 </span> <span class="subxComment"># 0x4000 bit = configure linear frame buffer in Bochs emulator; hopefully this doesn't hurt anything when running natively</span>
<span id="L119" class="LineNr"> 119 </span> cd/syscall 0x10/imm8/bios-video-services
<span id="L120" class="LineNr"> 120 </span>
<span id="L121" class="LineNr"> 121 </span> <span class="subxComment"># load information for the (hopefully) current video mode</span>
<span id="L122" class="LineNr"> 122 </span> <span class="subxComment"># mostly just for the address to the linear frame buffer</span>
<span id="L123" class="LineNr"> 123 </span> b4/copy-to-ah 0x4f/imm8 <span class="subxComment"># VBE commands</span>
<span id="L124" class="LineNr"> 124 </span> b0/copy-to-al 1/imm8 <span class="subxComment"># get video mode info</span>
<span id="L125" class="LineNr"> 125 </span> b9/copy-to-cx 0x0105/imm16 <span class="subxComment"># mode we requested</span>
<span id="L126" class="LineNr"> 126 </span> bf/copy-to-di <span class="SpecialChar"><a href='boot.subx.html#L385'>Video-mode-info</a></span>/imm16
<span id="L127" class="LineNr"> 127 </span> cd/syscall 0x10/imm8/bios-video-services
<span id="L128" class="LineNr"> 128 </span>
<span id="L129" class="LineNr"> 129 </span> <span class="subxComment">## switch to 32-bit mode</span>
<span id="L130" class="LineNr"> 130 </span> <span class="subxComment"># load global descriptor table</span>
<span id="L131" class="LineNr"> 131 </span> <span class="subxComment"># We can't refer to the label directly because SubX doesn't do the right</span>
<span id="L132" class="LineNr"> 132 </span> <span class="subxComment"># thing for lgdt, so rather than make errors worse in most places we instead</span>
<span id="L133" class="LineNr"> 133 </span> <span class="subxComment"># pin gdt_descriptor below.</span>
<span id="L134" class="LineNr"> 134 </span> 0f 01 2/subop/lgdt 0/mod/indirect 6/rm32/use-disp16 0x7cf8/disp16/gdt_descriptor
<span id="L135" class="LineNr"> 135 </span> <span class="subxComment"># enable paging</span>
<span id="L136" class="LineNr"> 136 </span> 0f 20/&lt;-cr 3/mod/direct 0/rm32/eax 0/r32/cr0
<span id="L137" class="LineNr"> 137 </span> 66 83 1/subop/or 3/mod/direct 0/rm32/eax 1/imm8 <span class="subxComment"># eax &lt;- or 0x1</span>
<span id="L138" class="LineNr"> 138 </span> 0f 22/-&gt;cr 3/mod/direct 0/rm32/eax 0/r32/cr0
<span id="L139" class="LineNr"> 139 </span> <span class="subxComment"># far jump to initialize_32bit_mode that sets cs to offset 8 in the gdt in the process</span>
<span id="L140" class="LineNr"> 140 </span> <span class="subxComment"># We can't refer to the label directly because SubX doesn't have syntax for</span>
<span id="L141" class="LineNr"> 141 </span> <span class="subxComment"># segment selectors. So we instead pin initialize_32bit_mode below.</span>
<span id="L142" class="LineNr"> 142 </span> ea/jump-far-absolute 0x00087d00/disp32 <span class="subxComment"># address 0x7d00 in offset 8 of the gdt</span>
<span id="L143" class="LineNr"> 143 </span>
<span id="L144" class="LineNr"> 144 </span><span class="subxFunction">disk_error</span>:
<span id="L145" class="LineNr"> 145 </span> <span class="subxComment"># print 'D' to top-left of screen to indicate disk error</span>
<span id="L146" class="LineNr"> 146 </span> <span class="subxComment"># *0xb8000 &lt;- 0x0f44</span>
<span id="L147" class="LineNr"> 147 </span> bb/copy-to-bx 0xb800/imm16
<span id="L148" class="LineNr"> 148 </span> 8e/-&gt;seg 3/mod/direct 3/rm32/bx 3/r32/ds
<span id="L149" class="LineNr"> 149 </span> b0/copy-to-al 0x44/imm8/D
<span id="L150" class="LineNr"> 150 </span> b4/copy-to-ah 0x0f/imm8/white-on-black
<span id="L151" class="LineNr"> 151 </span> bb/copy-to-bx 0/imm16
<span id="L152" class="LineNr"> 152 </span> 89/&lt;- 0/mod/indirect 7/rm32/bx 0/r32/ax <span class="subxComment"># *ds:bx &lt;- ax</span>
<span id="L153" class="LineNr"> 153 </span> <span class="subxComment"># loop forever</span>
<span id="L154" class="LineNr"> 154 </span> {
<span id="L155" class="LineNr"> 155 </span> eb/jump <span class="Constant">loop</span>/disp8
<span id="L156" class="LineNr"> 156 </span> }
<span id="L157" class="LineNr"> 157 </span>
<span id="L158" class="LineNr"> 158 </span><span class="subxComment">## GDT: 3 records of 8 bytes each</span>
<span id="L159" class="LineNr"> 159 </span>== data
<span id="L160" class="LineNr"> 160 </span>
<span id="L161" class="LineNr"> 161 </span><span class="subxFunction">gdt_start</span>:
<span id="L162" class="LineNr"> 162 </span><span class="subxComment"># offset 0: gdt_null: mandatory null descriptor</span>
<span id="L163" class="LineNr"> 163 </span> 00 00 00 00 00 00 00 00
<span id="L164" class="LineNr"> 164 </span><span class="subxComment"># offset 8: gdt_code</span>
<span id="L165" class="LineNr"> 165 </span> ff ff <span class="subxComment"># limit[0:16]</span>
<span id="L166" class="LineNr"> 166 </span> 00 00 00 <span class="subxComment"># base[0:24]</span>
<span id="L167" class="LineNr"> 167 </span> 9a <span class="subxComment"># 1/present 00/privilege 1/descriptor type = 1001b</span>
<span id="L168" class="LineNr"> 168 </span> <span class="subxComment"># 1/code 0/conforming 1/readable 0/accessed = 1010b</span>
<span id="L169" class="LineNr"> 169 </span> cf <span class="subxComment"># 1/granularity 1/32-bit 0/64-bit-segment 0/AVL = 1100b</span>
<span id="L170" class="LineNr"> 170 </span> <span class="subxComment"># limit[16:20] = 1111b</span>
<span id="L171" class="LineNr"> 171 </span> 00 <span class="subxComment"># base[24:32]</span>
<span id="L172" class="LineNr"> 172 </span><span class="subxComment"># offset 16: gdt_data</span>
<span id="L173" class="LineNr"> 173 </span> ff ff <span class="subxComment"># limit[0:16]</span>
<span id="L174" class="LineNr"> 174 </span> 00 00 00 <span class="subxComment"># base[0:24]</span>
<span id="L175" class="LineNr"> 175 </span> 92 <span class="subxComment"># 1/present 00/privilege 1/descriptor type = 1001b</span>
<span id="L176" class="LineNr"> 176 </span> <span class="subxComment"># 0/data 0/conforming 1/readable 0/accessed = 0010b</span>
<span id="L177" class="LineNr"> 177 </span> cf <span class="subxComment"># same as gdt_code</span>
<span id="L178" class="LineNr"> 178 </span> 00 <span class="subxComment"># base[24:32]</span>
<span id="L179" class="LineNr"> 179 </span><span class="subxComment"># gdt_end:</span>
<span id="L180" class="LineNr"> 180 </span>
<span id="L181" class="LineNr"> 181 </span>== data 0x7cf8
<span id="L182" class="LineNr"> 182 </span><span class="subxFunction">gdt_descriptor</span>:
<span id="L183" class="LineNr"> 183 </span> 0x17/imm16 <span class="subxComment"># final index of gdt = size of gdt - 1</span>
<span id="L184" class="LineNr"> 184 </span> <a href='boot.subx.html#L161'>gdt_start</a>/imm32/start
<span id="L185" class="LineNr"> 185 </span>
<span id="L186" class="LineNr"> 186 </span><span class="subxComment">## 32-bit code from this point</span>
<span id="L187" class="LineNr"> 187 </span>
<span id="L188" class="LineNr"> 188 </span>== code 0x7d00
<span id="L189" class="LineNr"> 189 </span><span class="subxFunction">initialize_32bit_mode</span>:
<span id="L190" class="LineNr"> 190 </span> 66 b8/copy-to-ax 0x10/imm16 <span class="subxComment"># offset 16 from gdt_start</span>
<span id="L191" class="LineNr"> 191 </span> 8e/-&gt;seg 3/mod/direct 0/rm32/ax 3/r32/ds
<span id="L192" class="LineNr"> 192 </span> 8e/-&gt;seg 3/mod/direct 0/rm32/ax 2/r32/ss
<span id="L193" class="LineNr"> 193 </span> 8e/-&gt;seg 3/mod/direct 0/rm32/ax 0/r32/es
<span id="L194" class="LineNr"> 194 </span> 8e/-&gt;seg 3/mod/direct 0/rm32/ax 4/r32/fs
<span id="L195" class="LineNr"> 195 </span> 8e/-&gt;seg 3/mod/direct 0/rm32/ax 5/r32/gs
<span id="L196" class="LineNr"> 196 </span>
<span id="L197" class="LineNr"> 197 </span> bc/copy-to-esp 0x00070000/imm32
<span id="L198" class="LineNr"> 198 </span>
<span id="L199" class="LineNr"> 199 </span> <span class="subxComment">## load interrupt handlers</span>
<span id="L200" class="LineNr"> 200 </span> <span class="subxComment"># We can't refer to the label directly because SubX doesn't do the right</span>
<span id="L201" class="LineNr"> 201 </span> <span class="subxComment"># thing for lidt, so rather than make errors worse in most places we instead</span>
<span id="L202" class="LineNr"> 202 </span> <span class="subxComment"># pin idt_descriptor below.</span>
<span id="L203" class="LineNr"> 203 </span> 0f 01 3/subop/lidt 0/mod/indirect 5/rm32/use-disp32 0x8000/disp32/idt_descriptor
<span id="L204" class="LineNr"> 204 </span>
<span id="L205" class="LineNr"> 205 </span> <span class="subxComment"># For now, not bothering reprogramming the IRQ to not conflict with software</span>
<span id="L206" class="LineNr"> 206 </span> <span class="subxComment"># exceptions.</span>
<span id="L207" class="LineNr"> 207 </span> <span class="subxComment"># <a href="https://wiki.osdev.org/index.php?title=8259_PIC&amp;oldid=24650#Protected_Mode">https://wiki.osdev.org/index.php?title=8259_PIC&amp;oldid=24650#Protected_Mode</a></span>
<span id="L208" class="LineNr"> 208 </span> <span class="subxComment">#</span>
<span id="L209" class="LineNr"> 209 </span> <span class="subxComment"># Interrupt 1 (keyboard) conflicts with debugger faults. We don't use a</span>
<span id="L210" class="LineNr"> 210 </span> <span class="subxComment"># debugger.</span>
<span id="L211" class="LineNr"> 211 </span> <span class="subxComment"># Reference:</span>
<span id="L212" class="LineNr"> 212 </span> <span class="subxComment"># <a href="https://wiki.osdev.org/Exceptions">https://wiki.osdev.org/Exceptions</a></span>
<span id="L213" class="LineNr"> 213 </span>
<span id="L214" class="LineNr"> 214 </span> <span class="subxComment"># enable keyboard IRQ (1)</span>
<span id="L215" class="LineNr"> 215 </span> b0/copy-to-al 0xfd/imm8 <span class="subxComment"># disable mask for IRQ1</span>
<span id="L216" class="LineNr"> 216 </span> e6/write-al-into-port 0x21/imm8
<span id="L217" class="LineNr"> 217 </span>
<span id="L218" class="LineNr"> 218 </span> fb/enable-interrupts
<span id="L219" class="LineNr"> 219 </span>
<span id="L220" class="LineNr"> 220 </span> <span class="subxComment">## enable floating point</span>
<span id="L221" class="LineNr"> 221 </span> db/floating-point-coprocessor e3/initialize
<span id="L222" class="LineNr"> 222 </span> <span class="subxComment"># eax &lt;- cr4</span>
<span id="L223" class="LineNr"> 223 </span> 0f 20/&lt;-cr 3/mod/direct 0/rm32/eax 4/r32/cr4
<span id="L224" class="LineNr"> 224 </span> <span class="subxComment"># eax &lt;- or bit 9</span>
<span id="L225" class="LineNr"> 225 </span> 0f ba/bit-test 5/subop/bit-test-and-set 3/mod/direct 0/rm32/eax 9/imm8
<span id="L226" class="LineNr"> 226 </span> <span class="subxComment"># cr4 &lt;- eax</span>
<span id="L227" class="LineNr"> 227 </span> 0f 22/-&gt;cr 3/mod/direct 0/rm32/eax 4/r32/cr4
<span id="L228" class="LineNr"> 228 </span>
<span id="L229" class="LineNr"> 229 </span> e9/jump <span class="SpecialChar">Entry</span>/disp32
<span id="L230" class="LineNr"> 230 </span>
<span id="L231" class="LineNr"> 231 </span>== boot-sector-marker 0x7dfe
<span id="L232" class="LineNr"> 232 </span><span class="subxComment"># final 2 bytes of boot sector</span>
<span id="L233" class="LineNr"> 233 </span>55 aa
<span id="L234" class="LineNr"> 234 </span>
<span id="L235" class="LineNr"> 235 </span><span class="subxComment">## sector 2 onwards loaded by load_disk, not automatically on boot</span>
<span id="L236" class="LineNr"> 236 </span>== code
<span id="L237" class="LineNr"> 237 </span>
<span id="L238" class="LineNr"> 238 </span><span class="subxFunction">null-interrupt-handler</span>:
<span id="L239" class="LineNr"> 239 </span> cf/return-from-interrupt
<span id="L240" class="LineNr"> 240 </span>
<span id="L241" class="LineNr"> 241 </span><span class="subxFunction">keyboard-interrupt-handler</span>:
<span id="L242" class="LineNr"> 242 </span> <span class="subxComment"># prologue</span>
<span id="L243" class="LineNr"> 243 </span> fa/disable-interrupts
<span id="L244" class="LineNr"> 244 </span> 60/push-all-registers
<span id="L245" class="LineNr"> 245 </span> <span class="subxComment"># acknowledge interrupt</span>
<span id="L246" class="LineNr"> 246 </span> b0/copy-to-al 0x20/imm8
<span id="L247" class="LineNr"> 247 </span> e6/write-al-into-port 0x20/imm8
<span id="L248" class="LineNr"> 248 </span> 31/xor %eax 0/r32/eax
<span id="L249" class="LineNr"> 249 </span> <span class="subxComment"># check output buffer of 8042 keyboard controller (<a href="https://web.archive.org/web/20040604041507/http://panda.cs.ndsu.nodak.edu/~achapwes/PICmicro/keyboard/atkeyboard.html)">https://web.archive.org/web/20040604041507/http://panda.cs.ndsu.nodak.edu/~achapwes/PICmicro/keyboard/atkeyboard.html)</a></span>
<span id="L250" class="LineNr"> 250 </span> e4/read-port-into-al 0x64/imm8
<span id="L251" class="LineNr"> 251 </span> a8/test-bits-in-al 0x01/imm8 <span class="subxComment"># set zf if bit 0 (least significant) is not set</span>
<span id="L252" class="LineNr"> 252 </span> 74/jump-if-not-set $keyboard-interrupt-handler:epilogue/disp8
<span id="L253" class="LineNr"> 253 </span> <span class="subxH1Comment"># - if keyboard buffer is full, return</span>
<span id="L254" class="LineNr"> 254 </span> <span class="subxComment"># var dest-addr/ecx: (addr byte) = (keyboard-buffer + *keyboard-buffer:write)</span>
<span id="L255" class="LineNr"> 255 </span> 31/xor %ecx 1/r32/ecx
<span id="L256" class="LineNr"> 256 </span> 8a/byte-&gt; *<span class="SpecialChar">Keyboard-buffer</span>:<a href='108write.subx.html#L11'>write</a> 1/r32/cl
<span id="L257" class="LineNr"> 257 </span> 81 0/subop/add %ecx <span class="SpecialChar">Keyboard-buffer</span>:data/imm32
<span id="L258" class="LineNr"> 258 </span> <span class="subxComment"># al = *dest-addr</span>
<span id="L259" class="LineNr"> 259 </span> 8a/byte-&gt; *ecx 0/r32/al
<span id="L260" class="LineNr"> 260 </span> <span class="subxComment"># if (al != 0) return</span>
<span id="L261" class="LineNr"> 261 </span> 3c/compare-al-and 0/imm8
<span id="L262" class="LineNr"> 262 </span> 75/jump-if-!= $keyboard-interrupt-handler:epilogue/disp8
<span id="L263" class="LineNr"> 263 </span> <span class="subxH1Comment"># - read keycode</span>
<span id="L264" class="LineNr"> 264 </span> e4/read-port-into-al 0x60/imm8
<span id="L265" class="LineNr"> 265 </span> <span class="subxH1Comment"># - key released</span>
<span id="L266" class="LineNr"> 266 </span> <span class="subxComment"># if (al == 0xaa) shift = false # left shift is being lifted</span>
<span id="L267" class="LineNr"> 267 </span> {
<span id="L268" class="LineNr"> 268 </span> 3c/compare-al-and 0xaa/imm8
<span id="L269" class="LineNr"> 269 </span> 75/jump-if-!= <span class="Constant">break</span>/disp8
<span id="L270" class="LineNr"> 270 </span> <span class="subxComment"># *shift = 0</span>
<span id="L271" class="LineNr"> 271 </span> c7 0/subop/copy *Keyboard-shift-pressed? 0/imm32
<span id="L272" class="LineNr"> 272 </span> }
<span id="L273" class="LineNr"> 273 </span> <span class="subxComment"># if (al == 0xb6) shift = false # right shift is being lifted</span>
<span id="L274" class="LineNr"> 274 </span> {
<span id="L275" class="LineNr"> 275 </span> 3c/compare-al-and 0xb6/imm8
<span id="L276" class="LineNr"> 276 </span> 75/jump-if-!= <span class="Constant">break</span>/disp8
<span id="L277" class="LineNr"> 277 </span> <span class="subxComment"># *shift = 0</span>
<span id="L278" class="LineNr"> 278 </span> c7 0/subop/copy *Keyboard-shift-pressed? 0/imm32
<span id="L279" class="LineNr"> 279 </span> }
<span id="L280" class="LineNr"> 280 </span> <span class="subxComment"># if (al == 0x9d) ctrl = false # ctrl is being lifted</span>
<span id="L281" class="LineNr"> 281 </span> {
<span id="L282" class="LineNr"> 282 </span> 3c/compare-al-and 0x9d/imm8
<span id="L283" class="LineNr"> 283 </span> 75/jump-if-!= <span class="Constant">break</span>/disp8
<span id="L284" class="LineNr"> 284 </span> <span class="subxComment"># *ctrl = 0</span>
<span id="L285" class="LineNr"> 285 </span> c7 0/subop/copy *Keyboard-ctrl-pressed? 0/imm32
<span id="L286" class="LineNr"> 286 </span> }
<span id="L287" class="LineNr"> 287 </span> <span class="subxComment"># if (al &amp; 0x80) a key is being lifted; return</span>
<span id="L288" class="LineNr"> 288 </span> 50/push-eax
<span id="L289" class="LineNr"> 289 </span> 24/and-al-with 0x80/imm8
<span id="L290" class="LineNr"> 290 </span> 3c/compare-al-and 0/imm8
<span id="L291" class="LineNr"> 291 </span> 58/pop-to-eax
<span id="L292" class="LineNr"> 292 </span> 75/jump-if-!= $keyboard-interrupt-handler:epilogue/disp8
<span id="L293" class="LineNr"> 293 </span> <span class="subxH1Comment"># - key pressed</span>
<span id="L294" class="LineNr"> 294 </span> <span class="subxComment"># if (al == 0x2a) shift = true, return # left shift pressed</span>
<span id="L295" class="LineNr"> 295 </span> {
<span id="L296" class="LineNr"> 296 </span> 3c/compare-al-and 0x2a/imm8
<span id="L297" class="LineNr"> 297 </span> 75/jump-if-!= <span class="Constant">break</span>/disp8
<span id="L298" class="LineNr"> 298 </span> <span class="subxComment"># *shift = 1</span>
<span id="L299" class="LineNr"> 299 </span> c7 0/subop/copy *Keyboard-shift-pressed? 1/imm32
<span id="L300" class="LineNr"> 300 </span> <span class="subxComment"># return</span>
<span id="L301" class="LineNr"> 301 </span> eb/jump $keyboard-interrupt-handler:epilogue/disp8
<span id="L302" class="LineNr"> 302 </span> }
<span id="L303" class="LineNr"> 303 </span> <span class="subxComment"># if (al == 0x36) shift = true, return # right shift pressed</span>
<span id="L304" class="LineNr"> 304 </span> {
<span id="L305" class="LineNr"> 305 </span> 3c/compare-al-and 0x36/imm8
<span id="L306" class="LineNr"> 306 </span> 75/jump-if-!= <span class="Constant">break</span>/disp8
<span id="L307" class="LineNr"> 307 </span> <span class="subxComment"># *shift = 1</span>
<span id="L308" class="LineNr"> 308 </span> c7 0/subop/copy *Keyboard-shift-pressed? 1/imm32
<span id="L309" class="LineNr"> 309 </span> <span class="subxComment"># return</span>
<span id="L310" class="LineNr"> 310 </span> eb/jump $keyboard-interrupt-handler:epilogue/disp8
<span id="L311" class="LineNr"> 311 </span> }
<span id="L312" class="LineNr"> 312 </span> <span class="subxComment"># if (al == 0x1d) ctrl = true, return</span>
<span id="L313" class="LineNr"> 313 </span> {
<span id="L314" class="LineNr"> 314 </span> 3c/compare-al-and 0x1d/imm8
<span id="L315" class="LineNr"> 315 </span> 75/jump-if-!= <span class="Constant">break</span>/disp8
<span id="L316" class="LineNr"> 316 </span> <span class="subxComment"># *ctrl = 1</span>
<span id="L317" class="LineNr"> 317 </span> c7 0/subop/copy *Keyboard-ctrl-pressed? 1/imm32
<span id="L318" class="LineNr"> 318 </span> <span class="subxComment"># return</span>
<span id="L319" class="LineNr"> 319 </span> eb/jump $keyboard-interrupt-handler:epilogue/disp8
<span id="L320" class="LineNr"> 320 </span> }
<span id="L321" class="LineNr"> 321 </span> <span class="subxH1Comment"># - convert key to character</span>
<span id="L322" class="LineNr"> 322 </span> <span class="subxComment"># if (shift) use keyboard shift map</span>
<span id="L323" class="LineNr"> 323 </span> {
<span id="L324" class="LineNr"> 324 </span> 81 7/subop/compare *Keyboard-shift-pressed? 0/imm32
<span id="L325" class="LineNr"> 325 </span> 74/jump-if-= <span class="Constant">break</span>/disp8
<span id="L326" class="LineNr"> 326 </span> <span class="subxComment"># sigils don't currently support labels inside *(eax+label)</span>
<span id="L327" class="LineNr"> 327 </span> 05/add-to-eax <span class="SpecialChar"><a href='boot.subx.html#L634'>Keyboard-shift-map</a></span>/imm32
<span id="L328" class="LineNr"> 328 </span> 8a/byte-&gt; *eax 0/r32/al
<span id="L329" class="LineNr"> 329 </span> eb/jump $keyboard-interrupt-handler:select-map-done/disp8
<span id="L330" class="LineNr"> 330 </span> }
<span id="L331" class="LineNr"> 331 </span> <span class="subxComment"># if (ctrl) al = *(ctrl map + al)</span>
<span id="L332" class="LineNr"> 332 </span> {
<span id="L333" class="LineNr"> 333 </span> 81 7/subop/compare *Keyboard-ctrl-pressed? 0/imm32
<span id="L334" class="LineNr"> 334 </span> 74/jump-if-= <span class="Constant">break</span>/disp8
<span id="L335" class="LineNr"> 335 </span> 05/add-to-eax <span class="SpecialChar"><a href='boot.subx.html#L661'>Keyboard-ctrl-map</a></span>/imm32
<span id="L336" class="LineNr"> 336 </span> 8a/byte-&gt; *eax 0/r32/al
<span id="L337" class="LineNr"> 337 </span> eb/jump $keyboard-interrupt-handler:select-map-done/disp8
<span id="L338" class="LineNr"> 338 </span> }
<span id="L339" class="LineNr"> 339 </span> <span class="subxComment"># otherwise al = *(normal map + al)</span>
<span id="L340" class="LineNr"> 340 </span> 05/add-to-eax <span class="SpecialChar"><a href='boot.subx.html#L605'>Keyboard-normal-map</a></span>/imm32
<span id="L341" class="LineNr"> 341 </span> 8a/byte-&gt; *eax 0/r32/al
<span id="L342" class="LineNr"> 342 </span><span class="Constant">$keyboard-interrupt-handler:select-map-done</span>:
<span id="L343" class="LineNr"> 343 </span> <span class="subxH1Comment"># - if there's no character mapping, return</span>
<span id="L344" class="LineNr"> 344 </span> {
<span id="L345" class="LineNr"> 345 </span> 3c/compare-al-and 0/imm8
<span id="L346" class="LineNr"> 346 </span> 74/jump-if-= <span class="Constant">break</span>/disp8
<span id="L347" class="LineNr"> 347 </span> <span class="subxH1Comment"># - store al in keyboard buffer</span>
<span id="L348" class="LineNr"> 348 </span> 88/&lt;- *ecx 0/r32/al
<span id="L349" class="LineNr"> 349 </span> <span class="subxComment"># increment index</span>
<span id="L350" class="LineNr"> 350 </span> fe/increment-byte *<span class="SpecialChar">Keyboard-buffer</span>:<a href='108write.subx.html#L11'>write</a>
<span id="L351" class="LineNr"> 351 </span> <span class="subxComment"># clear top nibble of index (keyboard buffer is circular)</span>
<span id="L352" class="LineNr"> 352 </span> 80 4/subop/and-byte *<span class="SpecialChar">Keyboard-buffer</span>:<a href='108write.subx.html#L11'>write</a> 0x0f/imm8
<span id="L353" class="LineNr"> 353 </span> }
<span id="L354" class="LineNr"> 354 </span><span class="Constant">$keyboard-interrupt-handler:epilogue</span>:
<span id="L355" class="LineNr"> 355 </span> <span class="subxComment"># epilogue</span>
<span id="L356" class="LineNr"> 356 </span> 61/pop-all-registers
<span id="L357" class="LineNr"> 357 </span> fb/enable-interrupts
<span id="L358" class="LineNr"> 358 </span> cf/return-from-interrupt
<span id="L359" class="LineNr"> 359 </span>
<span id="L360" class="LineNr"> 360 </span><span class="subxComment">## the rest of this file is all data</span>
<span id="L361" class="LineNr"> 361 </span>
<span id="L362" class="LineNr"> 362 </span>== data 0x8000
<span id="L363" class="LineNr"> 363 </span><span class="subxFunction">idt_descriptor</span>:
<span id="L364" class="LineNr"> 364 </span> ff 03 <span class="subxComment"># final index of idt = size of idt - 1</span>
<span id="L365" class="LineNr"> 365 </span> <a href='boot.subx.html#L443'>idt_start</a>/imm32/start
<span id="L366" class="LineNr"> 366 </span>
<span id="L367" class="LineNr"> 367 </span>Keyboard-shift-pressed?: <span class="subxComment"># boolean</span>
<span id="L368" class="LineNr"> 368 </span> 0/imm32
<span id="L369" class="LineNr"> 369 </span>
<span id="L370" class="LineNr"> 370 </span>Keyboard-ctrl-pressed?: <span class="subxComment"># boolean</span>
<span id="L371" class="LineNr"> 371 </span> 0/imm32
<span id="L372" class="LineNr"> 372 </span>
<span id="L373" class="LineNr"> 373 </span><span class="subxComment"># var keyboard circular buffer</span>
<span id="L374" class="LineNr"> 374 </span><span class="SpecialChar">Keyboard-buffer</span>:<a href='108write.subx.html#L11'>write</a>: <span class="subxComment"># nibble</span>
<span id="L375" class="LineNr"> 375 </span> 0/imm32
<span id="L376" class="LineNr"> 376 </span><span class="SpecialChar">Keyboard-buffer</span>:read: <span class="subxComment"># nibble</span>
<span id="L377" class="LineNr"> 377 </span> 0/imm32
<span id="L378" class="LineNr"> 378 </span><span class="SpecialChar">Keyboard-buffer</span>:data: <span class="subxComment"># byte[16]</span>
<span id="L379" class="LineNr"> 379 </span> 00 00 00 00
<span id="L380" class="LineNr"> 380 </span> 00 00 00 00
<span id="L381" class="LineNr"> 381 </span> 00 00 00 00
<span id="L382" class="LineNr"> 382 </span> 00 00 00 00
<span id="L383" class="LineNr"> 383 </span>
<span id="L384" class="LineNr"> 384 </span>== data 0x8100
<span id="L385" class="LineNr"> 385 </span><span class="SpecialChar">Video-mode-info</span>:
<span id="L386" class="Folded"> 386 </span><span class="Folded">+-- 53 lines: # video mode info ---------------------------------------------------------------------------------------------------------------------------------------------------------</span>
<span id="L439" class="LineNr"> 439 </span>
<span id="L440" class="LineNr"> 440 </span>== data 0x8200
<span id="L441" class="Folded"> 441 </span><span class="Folded">+--161 lines: # interrupt descriptor table ----------------------------------------------------------------------------------------------------------------------------------------------</span>
<span id="L602" class="LineNr"> 602 </span>
<span id="L603" class="LineNr"> 603 </span>== data 0x8600
<span id="L604" class="Folded"> 604 </span><span class="Folded">+-- 72 lines: # translating keys to ASCII -----------------------------------------------------------------------------------------------------------------------------------------------</span>
<span id="L676" class="LineNr"> 676 </span>
<span id="L677" class="LineNr"> 677 </span>== data 0x8c00
<span id="L678" class="LineNr"> 678 </span><span class="SpecialChar">Font</span>:
<span id="L679" class="Folded"> 679 </span><span class="Folded">+--236 lines: # Bitmaps for some ASCII characters (soon Unicode) ------------------------------------------------------------------------------------------------------------------------</span>
<span id="L915" class="LineNr"> 915 </span>
<span id="L916" class="LineNr"> 916 </span><span class="subxComment"># offset 1800 (address 0x9400)</span>
<span id="L917" class="LineNr"> 917 </span>== code 0x9400
<span id="L918" class="LineNr"> 918 </span>
<span id="L919" class="LineNr"> 919 </span><span class="subxComment"># Use 28-bit PIO mode to read the first sector (512 bytes) from an IDE (ATA)</span>
<span id="L920" class="LineNr"> 920 </span><span class="subxComment"># disk drive.</span>
<span id="L921" class="LineNr"> 921 </span><span class="subxComment"># Inspired by <a href="https://colorforth.github.io/ide.html">https://colorforth.github.io/ide.html</a></span>
<span id="L922" class="LineNr"> 922 </span><span class="subxComment">#</span>
<span id="L923" class="LineNr"> 923 </span><span class="subxComment"># Resources:</span>
<span id="L924" class="LineNr"> 924 </span><span class="subxComment"># <a href="https://wiki.osdev.org/ATA_PIO_Mode">https://wiki.osdev.org/ATA_PIO_Mode</a></span>
<span id="L925" class="LineNr"> 925 </span><span class="subxComment"># <a href="https://forum.osdev.org/viewtopic.php?f=1&amp;p=167798">https://forum.osdev.org/viewtopic.php?f=1&amp;p=167798</a></span>
<span id="L926" class="LineNr"> 926 </span><span class="subxComment"># read-sector, according to <a href="https://www.scs.stanford.edu/11wi-cs140/pintos/specs/ata-3-std.pdf">https://www.scs.stanford.edu/11wi-cs140/pintos/specs/ata-3-std.pdf</a></span>
<span id="L927" class="LineNr"> 927 </span><span class="subxFunction">load-first-sector-from-primary-bus-secondary-drive</span>: <span class="subxComment"># out: (addr stream byte)</span>
<span id="L928" class="LineNr"> 928 </span> <span class="subxS1Comment"># . prologue</span>
<span id="L929" class="LineNr"> 929 </span> 55/push-ebp
<span id="L930" class="LineNr"> 930 </span> 89/&lt;- %ebp 4/r32/esp
<span id="L931" class="LineNr"> 931 </span> <span class="subxS1Comment"># . save registers</span>
<span id="L932" class="LineNr"> 932 </span> 50/push-eax
<span id="L933" class="LineNr"> 933 </span> 51/push-ecx
<span id="L934" class="LineNr"> 934 </span> 52/push-edx
<span id="L935" class="LineNr"> 935 </span> <span class="subxComment"># check for drive</span>
<span id="L936" class="LineNr"> 936 </span> (<a href='boot.subx.html#L1059'>secondary-drive-exists?</a>) <span class="subxComment"># =&gt; eax</span>
<span id="L937" class="LineNr"> 937 </span> 3d/compare-eax-and 0/imm32/false
<span id="L938" class="LineNr"> 938 </span> 0f 84/jump-if-= $load-first-sector-from-primary-bus-secondary-drive:end/disp32
<span id="L939" class="LineNr"> 939 </span> <span class="subxComment"># kick off read</span>
<span id="L940" class="LineNr"> 940 </span> (<a href='boot.subx.html#L1119'>ata-drive-select</a> 0xf0) <span class="subxComment"># primary bus, secondary drive; 4 LSBs contain 4 upper bits of LBA (here 0)</span>
<span id="L941" class="LineNr"> 941 </span> (<a href='boot.subx.html#L1139'>clear-ata-error</a>)
<span id="L942" class="LineNr"> 942 </span> (<a href='boot.subx.html#L1159'>ata-sector-count</a> 1)
<span id="L943" class="LineNr"> 943 </span> (<a href='boot.subx.html#L1179'>ata-lba</a> 0 0 0) <span class="subxComment"># lower 24 bits of LBA, all 0</span>
<span id="L944" class="LineNr"> 944 </span> (<a href='boot.subx.html#L1237'>ata-command</a> 0x20) <span class="subxComment"># read sectors with retries</span>
<span id="L945" class="LineNr"> 945 </span> <span class="subxComment"># poll for results</span>
<span id="L946" class="LineNr"> 946 </span> (<a href='boot.subx.html#L1257'>while-ata-busy</a>)
<span id="L947" class="LineNr"> 947 </span> (<a href='boot.subx.html#L1275'>until-ata-data-available</a>)
<span id="L948" class="LineNr"> 948 </span> <span class="subxComment"># emit results</span>
<span id="L949" class="LineNr"> 949 </span> 31/xor %eax 0/r32/eax
<span id="L950" class="LineNr"> 950 </span> ba/copy-to-edx 0x1f0/imm32
<span id="L951" class="LineNr"> 951 </span> b9/copy-to-ecx 0x200/imm32 <span class="subxComment"># 512 bytes per sector</span>
<span id="L952" class="LineNr"> 952 </span> {
<span id="L953" class="LineNr"> 953 </span> 81 7/subop/compare %ecx 0/imm32
<span id="L954" class="LineNr"> 954 </span> 74/jump-if-= <span class="Constant">break</span>/disp8
<span id="L955" class="LineNr"> 955 </span> 66 ed/read-port-dx-into-ax
<span id="L956" class="LineNr"> 956 </span> <span class="subxComment"># write 2 bytes to stream one at a time</span>
<span id="L957" class="LineNr"> 957 </span> (<a href='115write-byte.subx.html#L12'>append-byte</a> *(ebp+8) %eax)
<span id="L958" class="LineNr"> 958 </span> 49/decrement-ecx
<span id="L959" class="LineNr"> 959 </span> c1/shift 5/subop/right-padding-zeroes %eax 8/imm8
<span id="L960" class="LineNr"> 960 </span> (<a href='115write-byte.subx.html#L12'>append-byte</a> *(ebp+8) %eax)
<span id="L961" class="LineNr"> 961 </span> 49/decrement-ecx
<span id="L962" class="LineNr"> 962 </span> eb/jump <span class="Constant">loop</span>/disp8
<span id="L963" class="LineNr"> 963 </span> }
<span id="L964" class="LineNr"> 964 </span><span class="Constant">$load-first-sector-from-primary-bus-secondary-drive:end</span>:
<span id="L965" class="LineNr"> 965 </span> <span class="subxS1Comment"># . restore registers</span>
<span id="L966" class="LineNr"> 966 </span> 5a/pop-to-edx
<span id="L967" class="LineNr"> 967 </span> 59/pop-to-ecx
<span id="L968" class="LineNr"> 968 </span> 58/pop-to-eax
<span id="L969" class="LineNr"> 969 </span> <span class="subxS1Comment"># . epilogue</span>
<span id="L970" class="LineNr"> 970 </span> 89/&lt;- %esp 5/r32/ebp
<span id="L971" class="LineNr"> 971 </span> 5d/pop-to-ebp
<span id="L972" class="LineNr"> 972 </span> c3/return
<span id="L973" class="LineNr"> 973 </span>
<span id="L974" class="LineNr"> 974 </span><span class="subxFunction">store-first-sector-to-primary-bus-secondary-drive</span>: <span class="subxComment"># in: (addr stream byte)</span>
<span id="L975" class="LineNr"> 975 </span> <span class="subxS1Comment"># . prologue</span>
<span id="L976" class="LineNr"> 976 </span> 55/push-ebp
<span id="L977" class="LineNr"> 977 </span> 89/&lt;- %ebp 4/r32/esp
<span id="L978" class="LineNr"> 978 </span> <span class="subxS1Comment"># . save registers</span>
<span id="L979" class="LineNr"> 979 </span> 50/push-eax
<span id="L980" class="LineNr"> 980 </span> 51/push-ecx
<span id="L981" class="LineNr"> 981 </span> 52/push-edx
<span id="L982" class="LineNr"> 982 </span> 53/push-ebx
<span id="L983" class="LineNr"> 983 </span> <span class="subxComment"># check for drive</span>
<span id="L984" class="LineNr"> 984 </span> (<a href='boot.subx.html#L1059'>secondary-drive-exists?</a>) <span class="subxComment"># =&gt; eax</span>
<span id="L985" class="LineNr"> 985 </span> 3d/compare-eax-and 0/imm32/false
<span id="L986" class="LineNr"> 986 </span> 0f 84/jump-if-= $store-first-sector-to-primary-bus-secondary-drive:end/disp32
<span id="L987" class="LineNr"> 987 </span> <span class="subxComment"># kick off write</span>
<span id="L988" class="LineNr"> 988 </span> (<a href='boot.subx.html#L1119'>ata-drive-select</a> 0xf0) <span class="subxComment"># primary bus, secondary drive; 4 LSBs contain 4 upper bits of LBA (here 0)</span>
<span id="L989" class="LineNr"> 989 </span> (<a href='boot.subx.html#L1139'>clear-ata-error</a>)
<span id="L990" class="LineNr"> 990 </span> (<a href='boot.subx.html#L1159'>ata-sector-count</a> 1)
<span id="L991" class="LineNr"> 991 </span> (<a href='boot.subx.html#L1179'>ata-lba</a> 0 0 0) <span class="subxComment"># lower 24 bits of LBA, all 0</span>
<span id="L992" class="LineNr"> 992 </span> (<a href='boot.subx.html#L1237'>ata-command</a> 0x30) <span class="subxComment"># write sectors with retries</span>
<span id="L993" class="LineNr"> 993 </span> <span class="subxComment"># wait</span>
<span id="L994" class="LineNr"> 994 </span> (<a href='boot.subx.html#L1257'>while-ata-busy</a>)
<span id="L995" class="LineNr"> 995 </span> (<a href='boot.subx.html#L1293'>until-ata-ready-for-data</a>)
<span id="L996" class="LineNr"> 996 </span> <span class="subxComment"># send data</span>
<span id="L997" class="LineNr"> 997 </span> ba/copy-to-edx 0x1f0/imm32
<span id="L998" class="LineNr"> 998 </span> b9/copy-to-ecx 0x200/imm32 <span class="subxComment"># 512 bytes per sector</span>
<span id="L999" class="LineNr"> 999 </span> <span class="subxComment"># var first-byte/ebx: byte</span>
<span id="L1000" class="LineNr">1000 </span> <span class="subxComment"># when it's more than 0xff, we're at an even-numbered byte</span>
<span id="L1001" class="LineNr">1001 </span> bb/copy-to-ebx 0xffff/imm32
<span id="L1002" class="LineNr">1002 </span><span class="Constant">$store-first-sector-to-primary-bus-secondary-drive:loop</span>:
<span id="L1003" class="LineNr">1003 </span> {
<span id="L1004" class="LineNr">1004 </span> 81 7/subop/compare %ecx 0/imm32
<span id="L1005" class="LineNr">1005 </span> 74/jump-if-= <span class="Constant">break</span>/disp8
<span id="L1006" class="LineNr">1006 </span> <span class="subxComment"># this loop is slow, but the ATA spec also requires a small delay</span>
<span id="L1007" class="LineNr">1007 </span> (<a href='309stream.subx.html#L6'>stream-empty?</a> *(ebp+8)) <span class="subxComment"># =&gt; eax</span>
<span id="L1008" class="LineNr">1008 </span> 3d/compare-eax-and 0/imm32/false
<span id="L1009" class="LineNr">1009 </span> 75/jump-if-!= <span class="Constant">break</span>/disp8
<span id="L1010" class="LineNr">1010 </span> <span class="subxComment"># read byte from stream</span>
<span id="L1011" class="LineNr">1011 </span> (<a href='112read-byte.subx.html#L13'>read-byte</a> *(ebp+8)) <span class="subxComment"># =&gt; eax</span>
<span id="L1012" class="LineNr">1012 </span> <span class="subxComment"># if we're at an odd-numbered byte, save it to first-byte</span>
<span id="L1013" class="LineNr">1013 </span> 81 7/subop/compare %ebx 0xff/imm32
<span id="L1014" class="LineNr">1014 </span> {
<span id="L1015" class="LineNr">1015 </span> 7e/jump-if-&lt;= <span class="Constant">break</span>/disp8
<span id="L1016" class="LineNr">1016 </span> 89/&lt;- %ebx 0/r32/eax
<span id="L1017" class="LineNr">1017 </span> eb/jump $store-first-sector-to-primary-bus-secondary-drive:<span class="Constant">loop</span>/disp8
<span id="L1018" class="LineNr">1018 </span> }
<span id="L1019" class="LineNr">1019 </span> <span class="subxComment"># otherwise OR it with first-byte and write it out</span>
<span id="L1020" class="LineNr">1020 </span> c1/shift 4/subop/left %eax 8/imm8
<span id="L1021" class="LineNr">1021 </span> 09/or %eax 3/r32/ebx
<span id="L1022" class="LineNr">1022 </span> 66 ef/write-ax-into-port-dx
<span id="L1023" class="LineNr">1023 </span> 49/decrement-ecx
<span id="L1024" class="LineNr">1024 </span> 49/decrement-ecx
<span id="L1025" class="LineNr">1025 </span> <span class="subxComment"># reset first-byte</span>
<span id="L1026" class="LineNr">1026 </span> bb/copy-to-ebx 0xffff/imm32
<span id="L1027" class="LineNr">1027 </span> eb/jump <span class="Constant">loop</span>/disp8
<span id="L1028" class="LineNr">1028 </span> }
<span id="L1029" class="LineNr">1029 </span> <span class="subxComment"># write out first-byte if necessary</span>
<span id="L1030" class="LineNr">1030 </span> 81 7/subop/compare %ebx 0xff/imm32
<span id="L1031" class="LineNr">1031 </span> {
<span id="L1032" class="LineNr">1032 </span> 7f/jump-if-&gt; <span class="Constant">break</span>/disp8
<span id="L1033" class="LineNr">1033 </span> 89/&lt;- %eax 3/r32/ebx
<span id="L1034" class="LineNr">1034 </span> 66 ef/write-ax-into-port-dx
<span id="L1035" class="LineNr">1035 </span> 49/decrement-ecx
<span id="L1036" class="LineNr">1036 </span> 49/decrement-ecx
<span id="L1037" class="LineNr">1037 </span> }
<span id="L1038" class="LineNr">1038 </span> <span class="subxComment"># pad zeroes</span>
<span id="L1039" class="LineNr">1039 </span> 31/xor %eax 0/r32/eax
<span id="L1040" class="LineNr">1040 </span> {
<span id="L1041" class="LineNr">1041 </span> 81 7/subop/compare %ecx 0/imm32
<span id="L1042" class="LineNr">1042 </span> 74/jump-if-= <span class="Constant">break</span>/disp8
<span id="L1043" class="LineNr">1043 </span> 66 ef/write-ax-into-port-dx
<span id="L1044" class="LineNr">1044 </span> 49/decrement-ecx
<span id="L1045" class="LineNr">1045 </span> 49/decrement-ecx
<span id="L1046" class="LineNr">1046 </span> eb/jump <span class="Constant">loop</span>/disp8
<span id="L1047" class="LineNr">1047 </span> }
<span id="L1048" class="LineNr">1048 </span><span class="Constant">$store-first-sector-to-primary-bus-secondary-drive:end</span>:
<span id="L1049" class="LineNr">1049 </span> <span class="subxS1Comment"># . restore registers</span>
<span id="L1050" class="LineNr">1050 </span> 5b/pop-to-ebx
<span id="L1051" class="LineNr">1051 </span> 5a/pop-to-edx
<span id="L1052" class="LineNr">1052 </span> 59/pop-to-ecx
<span id="L1053" class="LineNr">1053 </span> 58/pop-to-eax
<span id="L1054" class="LineNr">1054 </span> <span class="subxS1Comment"># . epilogue</span>
<span id="L1055" class="LineNr">1055 </span> 89/&lt;- %esp 5/r32/ebp
<span id="L1056" class="LineNr">1056 </span> 5d/pop-to-ebp
<span id="L1057" class="LineNr">1057 </span> c3/return
<span id="L1058" class="LineNr">1058 </span>
<span id="L1059" class="LineNr">1059 </span><span class="subxFunction">secondary-drive-exists?</span>: <span class="subxComment"># -&gt; _/eax: boolean</span>
<span id="L1060" class="LineNr">1060 </span> <span class="subxS1Comment"># . prologue</span>
<span id="L1061" class="LineNr">1061 </span> 55/push-ebp
<span id="L1062" class="LineNr">1062 </span> 89/&lt;- %ebp 4/r32/esp
<span id="L1063" class="LineNr">1063 </span> <span class="subxS1Comment"># . save registers</span>
<span id="L1064" class="LineNr">1064 </span> 52/push-edx
<span id="L1065" class="LineNr">1065 </span> <span class="subxComment"># check for floating bus</span>
<span id="L1066" class="LineNr">1066 </span> {
<span id="L1067" class="LineNr">1067 </span> 31/xor %eax 0/r32/eax
<span id="L1068" class="LineNr">1068 </span> ba/copy-to-edx 0x1f7/imm32
<span id="L1069" class="LineNr">1069 </span> ec/read-port-dx-into-al
<span id="L1070" class="LineNr">1070 </span> 3d/compare-eax-and 0xff/imm32
<span id="L1071" class="LineNr">1071 </span> <span class="subxComment"># if eax is 0xff, primary bus has no drives</span>
<span id="L1072" class="LineNr">1072 </span> b8/copy-to-eax 0/imm32/false
<span id="L1073" class="LineNr">1073 </span> 74/jump-if-= $secondary-drive-exists?:end/disp8
<span id="L1074" class="LineNr">1074 </span> }
<span id="L1075" class="LineNr">1075 </span> <span class="subxComment"># identify</span>
<span id="L1076" class="LineNr">1076 </span> (<a href='boot.subx.html#L1119'>ata-drive-select</a> 0xb0) <span class="subxComment"># primary bus, secondary drive</span>
<span id="L1077" class="LineNr">1077 </span> (<a href='boot.subx.html#L1159'>ata-sector-count</a> 0)
<span id="L1078" class="LineNr">1078 </span> (<a href='boot.subx.html#L1179'>ata-lba</a> 0 0 0)
<span id="L1079" class="LineNr">1079 </span> (<a href='boot.subx.html#L1237'>ata-command</a> 0xec) <span class="subxComment"># identify</span>
<span id="L1080" class="LineNr">1080 </span> <span class="subxComment"># read status register</span>
<span id="L1081" class="LineNr">1081 </span> <span class="subxComment"># TODO: might need to spin here for 400ns: <a href="https://wiki.osdev.org/index.php?title=ATA_PIO_Mode&amp;oldid=25664#400ns_delays">https://wiki.osdev.org/index.php?title=ATA_PIO_Mode&amp;oldid=25664#400ns_delays</a></span>
<span id="L1082" class="LineNr">1082 </span> 31/xor %eax 0/r32/eax
<span id="L1083" class="LineNr">1083 </span> ba/copy-to-edx 0x1f7/imm32
<span id="L1084" class="LineNr">1084 </span> ec/read-port-dx-into-al
<span id="L1085" class="LineNr">1085 </span> <span class="subxComment"># if eax is 0, secondary drive does not exist</span>
<span id="L1086" class="LineNr">1086 </span> 3d/compare-eax-and 0/imm32
<span id="L1087" class="LineNr">1087 </span> {
<span id="L1088" class="LineNr">1088 </span> 74/jump-if-= <span class="Constant">break</span>/disp8
<span id="L1089" class="LineNr">1089 </span> b8/copy-to-eax 1/imm32/true
<span id="L1090" class="LineNr">1090 </span> eb/jump $secondary-drive-exists?:complete-identify/disp8
<span id="L1091" class="LineNr">1091 </span> }
<span id="L1092" class="LineNr">1092 </span> <span class="subxComment"># TODO: might need to perform remaining steps at <a href="https://wiki.osdev.org/index.php?title=ATA_PIO_Mode&amp;oldid=25664#IDENTIFY_command">https://wiki.osdev.org/index.php?title=ATA_PIO_Mode&amp;oldid=25664#IDENTIFY_command</a></span>
<span id="L1093" class="LineNr">1093 </span> b8/copy-to-eax 0/imm32/false
<span id="L1094" class="LineNr">1094 </span><span class="Constant">$secondary-drive-exists?:complete-identify</span>:
<span id="L1095" class="LineNr">1095 </span> 50/push-eax
<span id="L1096" class="LineNr">1096 </span> <span class="subxComment"># clear FIFO from the drive</span>
<span id="L1097" class="LineNr">1097 </span> ba/copy-to-edx 0x1f0/imm32
<span id="L1098" class="LineNr">1098 </span> b9/copy-to-ecx 0x200/imm32
<span id="L1099" class="LineNr">1099 </span> {
<span id="L1100" class="LineNr">1100 </span> 81 7/subop/compare %ecx 0/imm32
<span id="L1101" class="LineNr">1101 </span> 74/jump-if-= <span class="Constant">break</span>/disp8
<span id="L1102" class="LineNr">1102 </span> <span class="subxComment"># read 4 bytes</span>
<span id="L1103" class="LineNr">1103 </span> ed/read-port-dx-into-eax
<span id="L1104" class="LineNr">1104 </span> 49/decrement-ecx
<span id="L1105" class="LineNr">1105 </span> 49/decrement-ecx
<span id="L1106" class="LineNr">1106 </span> 49/decrement-ecx
<span id="L1107" class="LineNr">1107 </span> 49/decrement-ecx
<span id="L1108" class="LineNr">1108 </span> eb/jump <span class="Constant">loop</span>/disp8
<span id="L1109" class="LineNr">1109 </span> }
<span id="L1110" class="LineNr">1110 </span> 58/pop-to-eax
<span id="L1111" class="LineNr">1111 </span><span class="Constant">$secondary-drive-exists?:end</span>:
<span id="L1112" class="LineNr">1112 </span> <span class="subxS1Comment"># . restore registers</span>
<span id="L1113" class="LineNr">1113 </span> 5a/pop-to-edx
<span id="L1114" class="LineNr">1114 </span> <span class="subxS1Comment"># . epilogue</span>
<span id="L1115" class="LineNr">1115 </span> 89/&lt;- %esp 5/r32/ebp
<span id="L1116" class="LineNr">1116 </span> 5d/pop-to-ebp
<span id="L1117" class="LineNr">1117 </span> c3/return
<span id="L1118" class="LineNr">1118 </span>
<span id="L1119" class="LineNr">1119 </span><span class="subxFunction">ata-drive-select</span>: <span class="subxComment"># n: byte</span>
<span id="L1120" class="LineNr">1120 </span> <span class="subxS1Comment"># . prologue</span>
<span id="L1121" class="LineNr">1121 </span> 55/push-ebp
<span id="L1122" class="LineNr">1122 </span> 89/&lt;- %ebp 4/r32/esp
<span id="L1123" class="LineNr">1123 </span> <span class="subxS1Comment"># . save registers</span>
<span id="L1124" class="LineNr">1124 </span> 50/push-eax
<span id="L1125" class="LineNr">1125 </span> 52/push-edx
<span id="L1126" class="LineNr">1126 </span> <span class="subxComment">#</span>
<span id="L1127" class="LineNr">1127 </span> 8b/-&gt; *(ebp+8) 0/r32/eax
<span id="L1128" class="LineNr">1128 </span> ba/copy-to-edx 0x1f6/imm32
<span id="L1129" class="LineNr">1129 </span> ee/write-al-into-port-dx
<span id="L1130" class="LineNr">1130 </span><span class="Constant">$ata-drive-select:end</span>:
<span id="L1131" class="LineNr">1131 </span> <span class="subxS1Comment"># . restore registers</span>
<span id="L1132" class="LineNr">1132 </span> 5a/pop-to-edx
<span id="L1133" class="LineNr">1133 </span> 58/pop-to-eax
<span id="L1134" class="LineNr">1134 </span> <span class="subxS1Comment"># . epilogue</span>
<span id="L1135" class="LineNr">1135 </span> 89/&lt;- %esp 5/r32/ebp
<span id="L1136" class="LineNr">1136 </span> 5d/pop-to-ebp
<span id="L1137" class="LineNr">1137 </span> c3/return
<span id="L1138" class="LineNr">1138 </span>
<span id="L1139" class="LineNr">1139 </span><span class="subxFunction">clear-ata-error</span>:
<span id="L1140" class="LineNr">1140 </span> <span class="subxS1Comment"># . prologue</span>
<span id="L1141" class="LineNr">1141 </span> 55/push-ebp
<span id="L1142" class="LineNr">1142 </span> 89/&lt;- %ebp 4/r32/esp
<span id="L1143" class="LineNr">1143 </span> <span class="subxS1Comment"># . save registers</span>
<span id="L1144" class="LineNr">1144 </span> 50/push-eax
<span id="L1145" class="LineNr">1145 </span> 52/push-edx
<span id="L1146" class="LineNr">1146 </span> <span class="subxComment">#</span>
<span id="L1147" class="LineNr">1147 </span> b8/copy-to-eax 0/imm32
<span id="L1148" class="LineNr">1148 </span> ba/copy-to-edx 0x1f1/imm32
<span id="L1149" class="LineNr">1149 </span> ee/write-al-into-port-dx
<span id="L1150" class="LineNr">1150 </span><span class="Constant">$ata-error:end</span>:
<span id="L1151" class="LineNr">1151 </span> <span class="subxS1Comment"># . restore registers</span>
<span id="L1152" class="LineNr">1152 </span> 5a/pop-to-edx
<span id="L1153" class="LineNr">1153 </span> 58/pop-to-eax
<span id="L1154" class="LineNr">1154 </span> <span class="subxS1Comment"># . epilogue</span>
<span id="L1155" class="LineNr">1155 </span> 89/&lt;- %esp 5/r32/ebp
<span id="L1156" class="LineNr">1156 </span> 5d/pop-to-ebp
<span id="L1157" class="LineNr">1157 </span> c3/return
<span id="L1158" class="LineNr">1158 </span>
<span id="L1159" class="LineNr">1159 </span><span class="subxFunction">ata-sector-count</span>: <span class="subxComment"># n: byte</span>
<span id="L1160" class="LineNr">1160 </span> <span class="subxS1Comment"># . prologue</span>
<span id="L1161" class="LineNr">1161 </span> 55/push-ebp
<span id="L1162" class="LineNr">1162 </span> 89/&lt;- %ebp 4/r32/esp
<span id="L1163" class="LineNr">1163 </span> <span class="subxS1Comment"># . save registers</span>
<span id="L1164" class="LineNr">1164 </span> 50/push-eax
<span id="L1165" class="LineNr">1165 </span> 52/push-edx
<span id="L1166" class="LineNr">1166 </span> <span class="subxComment">#</span>
<span id="L1167" class="LineNr">1167 </span> 8b/-&gt; *(ebp+8) 0/r32/eax
<span id="L1168" class="LineNr">1168 </span> ba/copy-to-edx 0x1f2/imm32
<span id="L1169" class="LineNr">1169 </span> ee/write-al-into-port-dx
<span id="L1170" class="LineNr">1170 </span><span class="Constant">$ata-sector-count:end</span>:
<span id="L1171" class="LineNr">1171 </span> <span class="subxS1Comment"># . restore registers</span>
<span id="L1172" class="LineNr">1172 </span> 5a/pop-to-edx
<span id="L1173" class="LineNr">1173 </span> 58/pop-to-eax
<span id="L1174" class="LineNr">1174 </span> <span class="subxS1Comment"># . epilogue</span>
<span id="L1175" class="LineNr">1175 </span> 89/&lt;- %esp 5/r32/ebp
<span id="L1176" class="LineNr">1176 </span> 5d/pop-to-ebp
<span id="L1177" class="LineNr">1177 </span> c3/return
<span id="L1178" class="LineNr">1178 </span>
<span id="L1179" class="LineNr">1179 </span><span class="subxFunction">ata-lba</span>: <span class="subxComment"># lo: byte, mid: byte, hi: byte</span>
<span id="L1180" class="LineNr">1180 </span> <span class="subxS1Comment"># . prologue</span>
<span id="L1181" class="LineNr">1181 </span> 55/push-ebp
<span id="L1182" class="LineNr">1182 </span> 89/&lt;- %ebp 4/r32/esp
<span id="L1183" class="LineNr">1183 </span> <span class="subxS1Comment"># . save registers</span>
<span id="L1184" class="LineNr">1184 </span> 50/push-eax
<span id="L1185" class="LineNr">1185 </span> 52/push-edx
<span id="L1186" class="LineNr">1186 </span> <span class="subxComment"># lo</span>
<span id="L1187" class="LineNr">1187 </span> 8b/-&gt; *(ebp+8) 0/r32/eax
<span id="L1188" class="LineNr">1188 </span> ba/copy-to-edx 0x1f3/imm32
<span id="L1189" class="LineNr">1189 </span> ee/write-al-into-port-dx
<span id="L1190" class="LineNr">1190 </span> <span class="subxComment"># mid</span>
<span id="L1191" class="LineNr">1191 </span> 8b/-&gt; *(ebp+0xc) 0/r32/eax
<span id="L1192" class="LineNr">1192 </span> ba/copy-to-edx 0x1f4/imm32
<span id="L1193" class="LineNr">1193 </span> ee/write-al-into-port-dx
<span id="L1194" class="LineNr">1194 </span> <span class="subxComment"># hi</span>
<span id="L1195" class="LineNr">1195 </span> 8b/-&gt; *(ebp+0x10) 0/r32/eax
<span id="L1196" class="LineNr">1196 </span> ba/copy-to-edx 0x1f5/imm32
<span id="L1197" class="LineNr">1197 </span> ee/write-al-into-port-dx
<span id="L1198" class="LineNr">1198 </span><span class="Constant">$ata-lba:end</span>:
<span id="L1199" class="LineNr">1199 </span> <span class="subxS1Comment"># . restore registers</span>
<span id="L1200" class="LineNr">1200 </span> 5a/pop-to-edx
<span id="L1201" class="LineNr">1201 </span> 58/pop-to-eax
<span id="L1202" class="LineNr">1202 </span> <span class="subxS1Comment"># . epilogue</span>
<span id="L1203" class="LineNr">1203 </span> 89/&lt;- %esp 5/r32/ebp
<span id="L1204" class="LineNr">1204 </span> 5d/pop-to-ebp
<span id="L1205" class="LineNr">1205 </span> c3/return
<span id="L1206" class="LineNr">1206 </span>
<span id="L1207" class="LineNr">1207 </span><span class="subxComment"># sector: [1, 63]</span>
<span id="L1208" class="LineNr">1208 </span><span class="subxComment"># cylinder: [0, 1023]</span>
<span id="L1209" class="LineNr">1209 </span><span class="subxFunction">ata-cyl-sector</span>: <span class="subxComment"># sector: byte, cyl-lo: byte, cyl-hi: byte</span>
<span id="L1210" class="LineNr">1210 </span> <span class="subxS1Comment"># . prologue</span>
<span id="L1211" class="LineNr">1211 </span> 55/push-ebp
<span id="L1212" class="LineNr">1212 </span> 89/&lt;- %ebp 4/r32/esp
<span id="L1213" class="LineNr">1213 </span> <span class="subxS1Comment"># . save registers</span>
<span id="L1214" class="LineNr">1214 </span> 50/push-eax
<span id="L1215" class="LineNr">1215 </span> 52/push-edx
<span id="L1216" class="LineNr">1216 </span> <span class="subxComment"># sector</span>
<span id="L1217" class="LineNr">1217 </span> 8b/-&gt; *(ebp+8) 0/r32/eax
<span id="L1218" class="LineNr">1218 </span> ba/copy-to-edx 0x1f3/imm32
<span id="L1219" class="LineNr">1219 </span> ee/write-al-into-port-dx
<span id="L1220" class="LineNr">1220 </span> <span class="subxComment"># cyl-lo</span>
<span id="L1221" class="LineNr">1221 </span> 8b/-&gt; *(ebp+0xc) 0/r32/eax
<span id="L1222" class="LineNr">1222 </span> ba/copy-to-edx 0x1f4/imm32
<span id="L1223" class="LineNr">1223 </span> ee/write-al-into-port-dx
<span id="L1224" class="LineNr">1224 </span> <span class="subxComment"># cyl-hi</span>
<span id="L1225" class="LineNr">1225 </span> 8b/-&gt; *(ebp+0x10) 0/r32/eax
<span id="L1226" class="LineNr">1226 </span> ba/copy-to-edx 0x1f5/imm32
<span id="L1227" class="LineNr">1227 </span> ee/write-al-into-port-dx
<span id="L1228" class="LineNr">1228 </span><span class="Constant">$ata-lba:end</span>:
<span id="L1229" class="LineNr">1229 </span> <span class="subxS1Comment"># . restore registers</span>
<span id="L1230" class="LineNr">1230 </span> 5a/pop-to-edx
<span id="L1231" class="LineNr">1231 </span> 58/pop-to-eax
<span id="L1232" class="LineNr">1232 </span> <span class="subxS1Comment"># . epilogue</span>
<span id="L1233" class="LineNr">1233 </span> 89/&lt;- %esp 5/r32/ebp
<span id="L1234" class="LineNr">1234 </span> 5d/pop-to-ebp
<span id="L1235" class="LineNr">1235 </span> c3/return
<span id="L1236" class="LineNr">1236 </span>
<span id="L1237" class="LineNr">1237 </span><span class="subxFunction">ata-command</span>: <span class="subxComment"># cmd: byte</span>
<span id="L1238" class="LineNr">1238 </span> <span class="subxS1Comment"># . prologue</span>
<span id="L1239" class="LineNr">1239 </span> 55/push-ebp
<span id="L1240" class="LineNr">1240 </span> 89/&lt;- %ebp 4/r32/esp
<span id="L1241" class="LineNr">1241 </span> <span class="subxS1Comment"># . save registers</span>
<span id="L1242" class="LineNr">1242 </span> 50/push-eax
<span id="L1243" class="LineNr">1243 </span> 52/push-edx
<span id="L1244" class="LineNr">1244 </span> <span class="subxComment">#</span>
<span id="L1245" class="LineNr">1245 </span> 8b/-&gt; *(ebp+8) 0/r32/eax
<span id="L1246" class="LineNr">1246 </span> ba/copy-to-edx 0x1f7/imm32
<span id="L1247" class="LineNr">1247 </span> ee/write-al-into-port-dx
<span id="L1248" class="LineNr">1248 </span><span class="Constant">$ata-command:end</span>:
<span id="L1249" class="LineNr">1249 </span> <span class="subxS1Comment"># . restore registers</span>
<span id="L1250" class="LineNr">1250 </span> 5a/pop-to-edx
<span id="L1251" class="LineNr">1251 </span> 58/pop-to-eax
<span id="L1252" class="LineNr">1252 </span> <span class="subxS1Comment"># . epilogue</span>
<span id="L1253" class="LineNr">1253 </span> 89/&lt;- %esp 5/r32/ebp
<span id="L1254" class="LineNr">1254 </span> 5d/pop-to-ebp
<span id="L1255" class="LineNr">1255 </span> c3/return
<span id="L1256" class="LineNr">1256 </span>
<span id="L1257" class="LineNr">1257 </span><span class="subxFunction">while-ata-busy</span>:
<span id="L1258" class="LineNr">1258 </span> <span class="subxS1Comment"># . save registers</span>
<span id="L1259" class="LineNr">1259 </span> 50/push-eax
<span id="L1260" class="LineNr">1260 </span> 52/push-edx
<span id="L1261" class="LineNr">1261 </span> <span class="subxComment">#</span>
<span id="L1262" class="LineNr">1262 </span> ba/copy-to-edx 0x1f7/imm32
<span id="L1263" class="LineNr">1263 </span> {
<span id="L1264" class="LineNr">1264 </span> ec/read-port-dx-into-al
<span id="L1265" class="LineNr">1265 </span> a8/test-bits-in-al 0x80/imm8/bsy <span class="subxComment"># set zf if bit 7 (most significant) is not set</span>
<span id="L1266" class="LineNr">1266 </span> 75/jump-if-zf-not-set-and-bit-7-set <span class="Constant">loop</span>/disp8
<span id="L1267" class="LineNr">1267 </span> }
<span id="L1268" class="LineNr">1268 </span><span class="Constant">$while-ata-busy:end</span>:
<span id="L1269" class="LineNr">1269 </span> <span class="subxS1Comment"># . restore registers</span>
<span id="L1270" class="LineNr">1270 </span> 5a/pop-to-edx
<span id="L1271" class="LineNr">1271 </span> 58/pop-to-eax
<span id="L1272" class="LineNr">1272 </span> <span class="subxS1Comment"># . epilogue</span>
<span id="L1273" class="LineNr">1273 </span> c3/return
<span id="L1274" class="LineNr">1274 </span>
<span id="L1275" class="LineNr">1275 </span><span class="subxFunction">until-ata-data-available</span>:
<span id="L1276" class="LineNr">1276 </span> <span class="subxS1Comment"># . save registers</span>
<span id="L1277" class="LineNr">1277 </span> 50/push-eax
<span id="L1278" class="LineNr">1278 </span> 52/push-edx
<span id="L1279" class="LineNr">1279 </span> <span class="subxComment">#</span>
<span id="L1280" class="LineNr">1280 </span> ba/copy-to-edx 0x1f7/imm32
<span id="L1281" class="LineNr">1281 </span> {
<span id="L1282" class="LineNr">1282 </span> ec/read-port-dx-into-al
<span id="L1283" class="LineNr">1283 </span> a8/test-bits-in-al 8/imm8/drq <span class="subxComment"># set zf if bit 3 is not set</span>
<span id="L1284" class="LineNr">1284 </span> 74/jump-if-zf-set-and-bit-3-not-set <span class="Constant">loop</span>/disp8
<span id="L1285" class="LineNr">1285 </span> }
<span id="L1286" class="LineNr">1286 </span><span class="Constant">$while-ata-busy:end</span>:
<span id="L1287" class="LineNr">1287 </span> <span class="subxS1Comment"># . restore registers</span>
<span id="L1288" class="LineNr">1288 </span> 5a/pop-to-edx
<span id="L1289" class="LineNr">1289 </span> 58/pop-to-eax
<span id="L1290" class="LineNr">1290 </span> <span class="subxS1Comment"># . epilogue</span>
<span id="L1291" class="LineNr">1291 </span> c3/return
<span id="L1292" class="LineNr">1292 </span>
<span id="L1293" class="LineNr">1293 </span><span class="subxFunction">until-ata-ready-for-data</span>:
<span id="L1294" class="LineNr">1294 </span> (<a href='boot.subx.html#L1275'>until-ata-data-available</a>)
<span id="L1295" class="LineNr">1295 </span> c3/return
<span id="L1296" class="LineNr">1296 </span>
<span id="L1297" class="LineNr">1297 </span><span class="subxComment"># vim&#0058;ft=subx</span>
</pre>
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