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Kartik K. Agaram 2021-03-22 22:56:33 -07:00
parent 480daf408c
commit c0607ecca8
3 changed files with 12 additions and 14 deletions
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2
400.mu
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@ -9,7 +9,7 @@ sig draw-cursor-on-real-screen g: grapheme
sig read-key kbd: (addr keyboard) -> _/eax: byte
# disk
sig load-sector-string-from-primary-bus-secondary-drive LBAlo: byte, LBAmid: byte, LBAhi: byte, out: (addr stream byte)
sig load-first-sector-from-primary-bus-secondary-drive out: (addr stream byte)
# tests
sig count-test-failure

22
boot.subx
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@ -916,17 +916,15 @@ Font:
# offset 1800 (address 0x9400)
== code 0x9400
# Use 28-bit PIO mode to transfer a string spanning at most one sector (512
# bytes) of data.
# Use 28-bit PIO mode to read the first sector (512 bytes) from an IDE (ATA)
# disk drive.
# Inspired by https://colorforth.github.io/ide.html
#
# Resources:
# https://wiki.osdev.org/ATA_PIO_Mode
# https://forum.osdev.org/viewtopic.php?f=1&p=167798
# read-sector, according to https://www.scs.stanford.edu/11wi-cs140/pintos/specs/ata-3-std.pdf
#
# Currently assumes top 4 bits of the 28-bit LBA coordinate are 0.
load-sector-string-from-primary-bus-secondary-drive: # LBAlo: byte, LBAmid: byte, LBAhi: byte, out: (addr stream byte)
load-first-sector-from-primary-bus-secondary-drive: # out: (addr stream byte)
# . prologue
55/push-ebp
89/<- %ebp 4/r32/esp
@ -937,12 +935,12 @@ load-sector-string-from-primary-bus-secondary-drive: # LBAlo: byte, LBAmid: byt
# check for drive
(secondary-drive-exists?) # => eax
3d/compare-eax-and 0/imm32/false
0f 84/jump-if-= $load-sector-string-from-primary-bus-secondary-drive:end/disp32
0f 84/jump-if-= $load-first-sector-from-primary-bus-secondary-drive:end/disp32
# kick off read
(ata-drive-select 0xf0) # primary bus, secondary drive; 4 LSBs contain 4 upper bits of LBA (here 0)
(clear-ata-error)
(ata-sector-count 1)
(ata-lba *(ebp+8) *(ebp+0xc) *(ebp+0x10)) # lower 24 bits of LBA
(ata-lba 0 0 0) # lower 24 bits of LBA, all 0
(ata-command 0x20) # read sectors with retries
# poll for results
(poll-ata-primary-bus-primary-drive-regular-status-word)
@ -954,20 +952,20 @@ load-sector-string-from-primary-bus-secondary-drive: # LBAlo: byte, LBAmid: byt
74/jump-if-= break/disp8
ed/read-port-dx-into-eax
# write 4 bytes to stream one at a time
(append-byte *(ebp+0x14) %eax)
(append-byte *(ebp+8) %eax)
49/decrement-ecx
c1/shift 5/subop/right-padding-zeroes %eax 8/imm8
(append-byte *(ebp+0x14) %eax)
(append-byte *(ebp+8) %eax)
49/decrement-ecx
c1/shift 5/subop/right-padding-zeroes %eax 8/imm8
(append-byte *(ebp+0x14) %eax)
(append-byte *(ebp+8) %eax)
49/decrement-ecx
c1/shift 5/subop/right-padding-zeroes %eax 8/imm8
(append-byte *(ebp+0x14) %eax)
(append-byte *(ebp+8) %eax)
49/decrement-ecx
eb/jump loop/disp8
}
$load-sector-string-from-primary-bus-secondary-drive:end:
$load-first-sector-from-primary-bus-secondary-drive:end:
# . restore registers
5a/pop-to-edx
59/pop-to-ecx

2
shell/main.mu
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@ -28,7 +28,7 @@ fn load-sandbox-from-secondary-disk _self: (addr sandbox) {
var self/esi: (addr sandbox) <- copy _self
var s-storage: (stream byte 0x200)
var s/ebx: (addr stream byte) <- address s-storage
load-sector-string-from-primary-bus-secondary-drive 0/lbalo, 0/lbamid, 0/lbahi, s
load-first-sector-from-primary-bus-secondary-drive s
{
var done?/eax: boolean <- stream-empty? s
compare done?, 0/false