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mu/subx/074print-int-decimal.subx

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5118 - convert int to string
2019-04-24 03:25:04 +00:00
# Helper to print an int32 in decimal.
== code
# instruction effective address register displacement immediate
# . op subop mod rm32 base index scale r32
# . 1-3 bytes 3 bits 2 bits 3 bits 3 bits 3 bits 2 bits 2 bits 0/1/2/4 bytes 0/1/2/4 bytes
#? Entry: # run a single test, while debugging
implemented solution
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#? e8/call test-print-int32-decimal-negative/disp32
#?
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#? # syscall(exit, Num-test-failures)
#? 8b/copy 0/mod/indirect 5/rm32/.disp32 . . 3/r32/EBX Num-test-failures/disp32 # copy *Num-test-failures to EBX
#? b8/copy-to-EAX 1/imm32/exit
#? cd/syscall 0x80/imm8
print-int32-decimal: # out : (address stream), n : int32
5137 A few minor stylistic things that may ease reading, but not significantly enough that I care to force others to follow them: * no end-of-line comments for instructions without /rm32 * arguments either at tab stops or after 2 spaces * compare 'with' when using in asymmetric tests (greater/lesser), compare 'and' for symmetric equality checking * prefix internal labels with function name
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# pseudocode:
# push sentinel
# EAX, negative? = abs(n), sign(n)
# while true
# sign-extend EAX into EDX
# EAX, EDX = EAX/10, EAX%10
# EDX += '0'
# push EDX
# if (EAX == 0) break
# if negative?
# push '-'
# while true
# pop into EAX
# if (EAX == sentinel) break
# out->data[out->write] = AL
# ++out->write
# (based on K&R itoa: https://en.wikibooks.org/wiki/C_Programming/stdlib.h/itoa)
# (this pseudocode contains registers because operations like division
# require specific registers in x86)
implemented solution
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#
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# . prolog
55/push-EBP
89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP
# . save registers
implemented solution
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50/push-EAX
51/push-ECX
52/push-EDX
53/push-EBX
57/push-EDI
5138 Drop some redundant transfers between registers. The x86 instruction set can perform most operations on all available registers, and things are more comprehensible if each conceptual variable has a single location.
2019-05-04 21:07:37 +00:00
# ten/ECX = 10
b9/copy-to-ECX 0xa/imm32
5137 A few minor stylistic things that may ease reading, but not significantly enough that I care to force others to follow them: * no end-of-line comments for instructions without /rm32 * arguments either at tab stops or after 2 spaces * compare 'with' when using in asymmetric tests (greater/lesser), compare 'and' for symmetric equality checking * prefix internal labels with function name
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# push sentinel
68/push 0/imm32/sentinel
# EAX, negative?/EDI = abs(n), sign(n)
bf/copy-to-EDI 0/imm32/false
implemented solution
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8b/copy 1/mod/*+disp8 5/rm32/EBP . . . 0/r32/EAX 0xc/disp8 . # EAX = *(EBP+12)
5137 A few minor stylistic things that may ease reading, but not significantly enough that I care to force others to follow them: * no end-of-line comments for instructions without /rm32 * arguments either at tab stops or after 2 spaces * compare 'with' when using in asymmetric tests (greater/lesser), compare 'and' for symmetric equality checking * prefix internal labels with function name
2019-05-04 19:58:09 +00:00
3d/compare-EAX-with 0/imm32
5138 Drop some redundant transfers between registers. The x86 instruction set can perform most operations on all available registers, and things are more comprehensible if each conceptual variable has a single location.
2019-05-04 21:07:37 +00:00
7d/jump-if-greater-or-equal $print-int32-decimal:read-loop/disp8
5137 A few minor stylistic things that may ease reading, but not significantly enough that I care to force others to follow them: * no end-of-line comments for instructions without /rm32 * arguments either at tab stops or after 2 spaces * compare 'with' when using in asymmetric tests (greater/lesser), compare 'and' for symmetric equality checking * prefix internal labels with function name
2019-05-04 19:58:09 +00:00
f7 3/subop/negate 3/mod/direct 0/rm32/EAX . . . . . . # negate EAX
bf/copy-to-EDI 1/imm32/true
$print-int32-decimal:read-loop:
# EAX, EDX = EAX / 10, EAX % 10
implemented solution
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99/sign-extend-EAX-into-EDX
f7 7/subop/idiv 3/mod/direct 1/rm32/ECX . . . . . . # divide EDX:EAX by ECX, storing quotient in EAX and remainder in EDX
5137 A few minor stylistic things that may ease reading, but not significantly enough that I care to force others to follow them: * no end-of-line comments for instructions without /rm32 * arguments either at tab stops or after 2 spaces * compare 'with' when using in asymmetric tests (greater/lesser), compare 'and' for symmetric equality checking * prefix internal labels with function name
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# EDX += '0'
81 0/subop/add 3/mod/direct 2/rm32/EDX . . . . . 0x30/imm32 # add to EDX
# push EDX
implemented solution
2019-05-04 01:56:55 +00:00
52/push-EDX
5137 A few minor stylistic things that may ease reading, but not significantly enough that I care to force others to follow them: * no end-of-line comments for instructions without /rm32 * arguments either at tab stops or after 2 spaces * compare 'with' when using in asymmetric tests (greater/lesser), compare 'and' for symmetric equality checking * prefix internal labels with function name
2019-05-04 19:58:09 +00:00
# if (EAX == 0) break
implemented solution
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3d/compare-EAX-and 0/imm32
5137 A few minor stylistic things that may ease reading, but not significantly enough that I care to force others to follow them: * no end-of-line comments for instructions without /rm32 * arguments either at tab stops or after 2 spaces * compare 'with' when using in asymmetric tests (greater/lesser), compare 'and' for symmetric equality checking * prefix internal labels with function name
2019-05-04 19:58:09 +00:00
7f/jump-if-greater $print-int32-decimal:read-loop/disp8
$print-int32-decimal:read-break:
# if (negative?) push('-')
5138 Drop some redundant transfers between registers. The x86 instruction set can perform most operations on all available registers, and things are more comprehensible if each conceptual variable has a single location.
2019-05-04 21:07:37 +00:00
81 7/subop/compare 3/mod/direct 7/rm32/EDI . . . . . 0/imm32/false # compare EDI
5137 A few minor stylistic things that may ease reading, but not significantly enough that I care to force others to follow them: * no end-of-line comments for instructions without /rm32 * arguments either at tab stops or after 2 spaces * compare 'with' when using in asymmetric tests (greater/lesser), compare 'and' for symmetric equality checking * prefix internal labels with function name
2019-05-04 19:58:09 +00:00
74/jump-if-equal $print-int32-decimal:write/disp8
68/push 0x2d/imm32/-
$print-int32-decimal:write:
# EBX = out
implemented solution
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8b/copy 1/mod/*+disp8 5/rm32/EBP . . . 3/r32/EBX 8/disp8 . # copy *(EBP+8) to EBX
5137 A few minor stylistic things that may ease reading, but not significantly enough that I care to force others to follow them: * no end-of-line comments for instructions without /rm32 * arguments either at tab stops or after 2 spaces * compare 'with' when using in asymmetric tests (greater/lesser), compare 'and' for symmetric equality checking * prefix internal labels with function name
2019-05-04 19:58:09 +00:00
$print-int32-decimal:write-loop:
# pop into EAX
implemented solution
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58/pop-to-EAX
5137 A few minor stylistic things that may ease reading, but not significantly enough that I care to force others to follow them: * no end-of-line comments for instructions without /rm32 * arguments either at tab stops or after 2 spaces * compare 'with' when using in asymmetric tests (greater/lesser), compare 'and' for symmetric equality checking * prefix internal labels with function name
2019-05-04 19:58:09 +00:00
# if (EAX == sentinel) break
3d/compare-EAX-and 0/imm32/sentinel
74/jump-if-equal $print-int32-decimal:end/disp8
# out->data[out->write] = AL
# . ECX = out->write
implemented solution
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8b/copy 0/mod/indirect 3/rm32/EBX . . . 1/r32/ECX . . # ECX = *EBX
# . ECX = &out->data[out->write]
8d/copy-address 1/mod/*+disp8 4/rm32/sib 3/base/EBX 1/index/ECX . 1/r32/ECX 0xc/disp8 . # copy EBX+ECX+12 to ECX
# . out->data[out->write] = EAX
89/copy 0/mod/indirect 1/rm32/ECX . . . 0/r32/ECX . . # *ECX = EAX
# out->write++
5137 A few minor stylistic things that may ease reading, but not significantly enough that I care to force others to follow them: * no end-of-line comments for instructions without /rm32 * arguments either at tab stops or after 2 spaces * compare 'with' when using in asymmetric tests (greater/lesser), compare 'and' for symmetric equality checking * prefix internal labels with function name
2019-05-04 19:58:09 +00:00
ff 0/subop/increment 0/mod/indirect 3/rm32/EBX . . . . . . # increment *EBX
eb/jump $print-int32-decimal:write-loop/disp8
5118 - convert int to string
2019-04-24 03:25:04 +00:00
$print-int32-decimal:end:
# . restore registers
implemented solution
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57/pop-to-EDI
5b/pop-to-EBX
5a/pop-to-EDX
59/pop-to-ECX
58/pop-to-EAX
5118 - convert int to string
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# . epilog
89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP
5d/pop-to-EBP
c3/return
$print-int32-decimal:abort:
# . _write(2/stderr, error)
# . . push args
68/push "print-int32-decimal: out of space"/imm32
68/push 2/imm32/stderr
# . . call
e8/call _write/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
# . syscall(exit, 1)
bb/copy-to-EBX 1/imm32
b8/copy-to-EAX 1/imm32/exit
cd/syscall 0x80/imm8
# never gets here
test-print-int32-decimal:
5125
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# - check that a single-digit number converts correctly
5118 - convert int to string
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# setup
# . clear-stream(_test-stream)
# . . push args
68/push _test-stream/imm32
# . . call
e8/call clear-stream/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP
# print-int32-decimal(_test-stream, 9)
# . . push args
68/push 9/imm32
68/push _test-stream/imm32
# . . call
e8/call print-int32-decimal/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
# check-stream-equal(_test-stream, "9", msg)
# . . push args
68/push "F - test-print-int32-decimal"/imm32
68/push "9"/imm32
68/push _test-stream/imm32
# . . call
e8/call check-stream-equal/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add to ESP
5136 - test for a previous bug Thanks Charles Saternos for the bugfix in 4a0b4344a3!
2019-05-04 19:16:33 +00:00
# . end
c3/return
test-print-int32-decimal-zero:
# - check that 0 converts correctly
# setup
# . clear-stream(_test-stream)
# . . push args
68/push _test-stream/imm32
# . . call
e8/call clear-stream/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP
# print-int32-decimal(_test-stream, 0)
# . . push args
68/push 0/imm32
68/push _test-stream/imm32
# . . call
e8/call print-int32-decimal/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
# check-stream-equal(_test-stream, "0", msg)
# . . push args
68/push "F - test-print-int32-decimal-zero"/imm32
68/push "0"/imm32
68/push _test-stream/imm32
# . . call
e8/call check-stream-equal/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add to ESP
5118 - convert int to string
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# . end
c3/return
test-print-int32-decimal-multiple-digits:
5125
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# - check that a multi-digit number converts correctly
5118 - convert int to string
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# setup
# . clear-stream(_test-stream)
# . . push args
68/push _test-stream/imm32
# . . call
e8/call clear-stream/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP
# print-int32-decimal(_test-stream, 10)
# . . push args
68/push 0xa/imm32
68/push _test-stream/imm32
# . . call
e8/call print-int32-decimal/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
# check-stream-equal(_test-stream, "10", msg)
# . . push args
68/push "F - test-print-int32-decimal-multiple-digits"/imm32
68/push "10"/imm32
68/push _test-stream/imm32
# . . call
e8/call check-stream-equal/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add to ESP
# . end
c3/return
test-print-int32-decimal-negative:
5125
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# - check that a negative single-digit number converts correctly
5118 - convert int to string
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# setup
# . clear-stream(_test-stream)
# . . push args
68/push _test-stream/imm32
# . . call
e8/call clear-stream/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP
# print-int32-decimal(_test-stream, -9)
# . . push args
68/push -9/imm32
68/push _test-stream/imm32
# . . call
e8/call print-int32-decimal/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
#? # dump _test-stream {{{
#? # . write(2/stderr, "^")
#? # . . push args
#? 68/push "^"/imm32
#? 68/push 2/imm32/stderr
#? # . . call
#? e8/call write/disp32
#? # . . discard args
#? 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
#? # . write-stream(2/stderr, _test-stream)
#? # . . push args
#? 68/push _test-stream/imm32
#? 68/push 2/imm32/stderr
#? # . . call
#? e8/call write-stream/disp32
#? # . . discard args
#? 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
#? # . write(2/stderr, "$\n")
#? # . . push args
#? 68/push "$\n"/imm32
#? 68/push 2/imm32/stderr
#? # . . call
#? e8/call write/disp32
#? # . . discard args
#? 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
#? # }}}
# check-stream-equal(_test-stream, "-9", msg)
# . . push args
68/push "F - test-print-int32-decimal-negative"/imm32
68/push "-9"/imm32
68/push _test-stream/imm32
# . . call
e8/call check-stream-equal/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add to ESP
# . end
c3/return
test-print-int32-decimal-negative-multiple-digits:
5125
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# - check that a multi-digit number converts correctly
5118 - convert int to string
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# setup
# . clear-stream(_test-stream)
# . . push args
68/push _test-stream/imm32
# . . call
e8/call clear-stream/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP
# print-int32-decimal(_test-stream, -10)
# . . push args
68/push -0xa/imm32
68/push _test-stream/imm32
# . . call
e8/call print-int32-decimal/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP
# check-stream-equal(_test-stream, "-10", msg)
# . . push args
68/push "F - test-print-int32-decimal-negative-multiple-digits"/imm32
68/push "-10"/imm32
68/push _test-stream/imm32
# . . call
e8/call check-stream-equal/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add to ESP
# . end
c3/return
# . . vim:nowrap:textwidth=0