== 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
# read bytes from 'f' until (and including) a newline and store them into 's'
# 's' fails to grow if and only if no data found
# just abort if 's' is too small
read-line-buffered: # f : (address buffered-file), s : (address stream byte)
# pseudocode:
# while true
# if (s->write >= s->length) abort
# if (f->read >= f->write) populate stream from file
# if (f->write == 0) break
# AL = f->data[f->read]
# s->data[s->write] = AL
# ++f->read
# ++s->write
# if (AL == '\n') break
# . prologue
55/push-ebp
89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp
# . save registers
50/push-eax
51/push-ecx
52/push-edx
56/push-esi
57/push-edi
# esi = f
8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 6/r32/esi 8/disp8 . # copy *(ebp+8) to esi
# ecx = f->read
8b/copy 1/mod/*+disp8 6/rm32/esi . . . 1/r32/ecx 8/disp8 . # copy *(esi+8) to ecx
# edi = s
8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 7/r32/edi 0xc/disp8 . # copy *(ebp+12) to edi
# edx = s->write
8b/copy 0/mod/indirect 7/rm32/edi . . . 2/r32/edx . . # copy *edi to edx
$read-line-buffered:loop:
# if (s->write >= s->length) abort
3b/compare 1/mod/*+disp8 7/rm32/edi . . . 2/r32/edx 8/disp8 . # compare edx with *(edi+8)
7d/jump-if-greater-or-equal $read-line-buffered:abort/disp8
# if (f->read >= f->write) populate stream from file
3b/compare 1/mod/*+disp8 6/rm32/esi . . . 1/r32/ecx 4/disp8 . # compare ecx with *(esi+4)
7c/jump-if-lesser $read-line-buffered:from-stream/disp8
# . clear-stream(stream = f+4)
# . . push args
8d/copy-address 1/mod/*+disp8 6/rm32/esi . . . 0/r32/eax 4/disp8 . # copy esi+4 to eax
50/push-eax
# . . call
e8/call clear-stream/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp
# . f->read must now be 0; update its cache at ecx
31/xor 3/mod/direct 1/rm32/ecx . . . 1/r32/ecx . . # clear ecx
# . eax = read(f->fd, stream = f+4)
# . . push args
50/push-eax
ff 6/subop/push 0/mod/indirect 6/rm32/esi . . . . . . # push *esi
# . . call
e8/call read/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
# if (f->write == 0) break
# since f->read was initially 0, eax is the same as f->write
# . if (eax == 0) return true
3d/compare-eax-and 0/imm32
74/jump-if-equal $read-line-buffered:end/disp8
$read-line-buffered:from-stream:
# AL = f->data[f->read]
31/xor 3/mod/direct 0/rm32/eax . . . 0/r32/eax . . # clear eax
8a/copy-byte 1/mod/*+disp8 4/rm32/sib 6/base/esi 1/index/ecx . 0/r32/AL 0x10/disp8 . # copy byte at *(esi+ecx+16) to AL
# s->data[s->write] = AL
88/copy-byte 1/mod/*+disp8 4/rm32/sib 7/base/edi 2/index/edx . 0/r32/AL 0xc/disp8 . # copy AL to *(edi+edx+12)
# ++f->read
41/increment-ecx
# ++s->write
42/increment-edx
# if (AL == '\n') return
3d/compare-eax-and 0xa/imm32
75/jump-if-not-equal $read-line-buffered:loop/disp8
$read-line-buffered:end:
# save f->read
89/copy 1/mod/*+disp8 6/rm32/esi . . . 1/r32/ecx 8/disp8 . # copy ecx to *(esi+8)
# save s->write
89/copy 0/mod/indirect 7/rm32/edi . . . 2/r32/edx . . # copy edx to *edi
# . restore registers
5f/pop-to-edi
5e/pop-to-esi
5a/pop-to-edx
59/pop-to-ecx
58/pop-to-eax
# . epilogue
89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp
5d/pop-to-ebp
c3/return
$read-line-buffered:abort:
# . _write(2/stderr, error)
# . . push args
68/push "read-line-buffered: line too long\n"/imm32
68/push 2/imm32/stderr
# . . call
e8/call _write/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
# . syscall(exit, 1)
bb/copy-to-ebx 1/imm32
b8/copy-to-eax 1/imm32/exit
cd/syscall 0x80/imm8
# never gets here
test-read-line-buffered:
# - check that read-line-buffered stops at a newline
# setup
# . clear-stream(_test-stream)
# . . push args
68/push _test-stream/imm32
# . . call
e8/call clear-stream/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp
# . clear-stream($_test-buffered-file->buffer)
# . . push args
68/push $_test-buffered-file->buffer/imm32
# . . call
e8/call clear-stream/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp
# . clear-stream(_test-tmp-stream)
# . . push args
68/push _test-tmp-stream/imm32
# . . call
e8/call clear-stream/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp
# write(_test-stream, "ab\ncd")
# . . push args
68/push "ab\ncd"/imm32
68/push _test-stream/imm32
# . . call
e8/call write/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
# read a line from _test-stream (buffered by _test-buffered-file) into _test-tmp-stream
# . eax = read-line-buffered(_test-buffered-file, _test-tmp-stream)
# . . push args
68/push _test-tmp-stream/imm32
68/push _test-buffered-file/imm32
# . . call
e8/call read-line-buffered/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
# check-next-stream-line-equal(_test-tmp-stream, "ab", msg)
# . . push args
68/push "F - test-read-line-buffered"/imm32
68/push "ab"/imm32
68/push _test-tmp-stream/imm32
# . . call
e8/call check-next-stream-line-equal/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
# end
c3/return
test-read-line-buffered-reads-final-line-until-Eof:
# setup
# . clear-stream(_test-stream)
# . . push args
68/push _test-stream/imm32
# . . call
e8/call clear-stream/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp
# . clear-stream($_test-buffered-file->buffer)
# . . push args
68/push $_test-buffered-file->buffer/imm32
# . . call
e8/call clear-stream/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp
# . clear-stream(_test-tmp-stream)
# . . push args
68/push _test-tmp-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
# write(_test-stream, "cd")
# . . push args
68/push "cd"/imm32
68/push _test-stream/imm32
# . . call
e8/call write/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
# read a line from _test-stream (buffered by _test-buffered-file) into _test-tmp-stream
# . eax = read-line-buffered(_test-buffered-file, _test-tmp-stream)
# . . push args
68/push _test-tmp-stream/imm32
68/push _test-buffered-file/imm32
# . . call
e8/call read-line-buffered/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
# check-stream-equal(_test-tmp-stream, "cd", msg)
# . . push args
68/push "F - test-read-line-buffered-reads-final-line-until-Eof"/imm32
68/push "cd"/imm32
68/push _test-tmp-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
# read bytes from 'f' until (and including) a newline and store them into 's'
# 's' fails to grow if and only if no data found
# just abort if 's' is too small
read-line: # f : (address stream), s : (address stream byte)
# pseudocode:
# while true
# if (s->write >= s->length) abort
# if (f->read >= f->write) break
# AL = f->data[f->read]
# s->data[s->write] = AL
# ++f->read
# ++s->write
# if (AL == '\n') break
# . prologue
55/push-ebp
89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp
# . save registers
50/push-eax
51/push-ecx
52/push-edx
56/push-esi
57/push-edi
# esi = f
8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 6/r32/esi 8/disp8 . # copy *(ebp+8) to esi
# ecx = f->read
8b/copy 1/mod/*+disp8 6/rm32/esi . . . 1/r32/ecx 4/disp8 . # copy *(esi+4) to ecx
# edi = s
8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 7/r32/edi 0xc/disp8 . # copy *(ebp+12) to edi
# edx = s->write
8b/copy 0/mod/indirect 7/rm32/edi . . . 2/r32/edx . . # copy *edi to edx
$read-line:loop:
# if (s->write >= s->length) abort
3b/compare 1/mod/*+disp8 7/rm32/edi . . . 2/r32/edx 8/disp8 . # compare edx with *(edi+8)
0f 8d/jump-if-greater-or-equal $read-line:abort/disp32
# if (f->read >= f->write) break
3b/compare 0/mod/indirect 6/rm32/esi . . . 1/r32/ecx . . # compare ecx with *esi
7d/jump-if-greater-or-equal $read-line:end/disp8
# AL = f->data[f->read]
31/xor 3/mod/direct 0/rm32/eax . . . 0/r32/eax . . # clear eax
8a/copy-byte 1/mod/*+disp8 4/rm32/sib 6/base/esi 1/index/ecx . 0/r32/AL 0xc/disp8 . # copy byte at *(esi+ecx+12) to AL
# s->data[s->write] = AL
88/copy-byte 1/mod/*+disp8 4/rm32/sib 7/base/edi 2/index/edx . 0/r32/AL 0xc/disp8 . # copy AL to *(edi+edx+12)
# ++f->read
41/increment-ecx
# ++s->write
42/increment-edx
# if (AL == '\n') return
3d/compare-eax-and 0xa/imm32
0f 85/jump-if-not-equal $read-line:loop/disp32
$read-line:end:
# save f->read
89/copy 1/mod/*+disp8 6/rm32/esi . . . 1/r32/ecx 4/disp8 . # copy ecx to *(esi+4)
# save s->write
89/copy 0/mod/indirect 7/rm32/edi . . . 2/r32/edx . . # copy edx to *edi
# . restore registers
5f/pop-to-edi
5e/pop-to-esi
5a/pop-to-edx
59/pop-to-ecx
58/pop-to-eax
# . epilogue
89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp
5d/pop-to-ebp
c3/return
$read-line:abort:
# . _write(2/stderr, error)
# . . push args
68/push "read-line: line too long\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
# . syscall(exit, 1)
bb/copy-to-ebx 1/imm32
b8/copy-to-eax 1/imm32/exit
cd/syscall 0x80/imm8
# never gets here
test-read-line:
# - check that read-line stops at a newline
# 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
# . clear-stream(_test-tmp-stream)
# . . push args
68/push _test-tmp-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
# write(_test-stream, "ab\ncd")
# . . push args
68/push "ab\ncd"/imm32
68/push _test-stream/imm32
# . . call
e8/call write/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
# read a line from _test-stream into _test-tmp-stream
# . eax = read-line(_test-stream, _test-tmp-stream)
# . . push args
68/push _test-tmp-stream/imm32
68/push _test-stream/imm32
# . . call
e8/call read-line/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
# check-next-stream-line-equal(_test-tmp-stream, "ab", msg)
# . . push args
68/push "F - test-read-line"/imm32
68/push "ab"/imm32
68/push _test-tmp-stream/imm32
# . . call
e8/call check-next-stream-line-equal/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
# end
c3/return
test-read-line-reads-final-line-until-Eof:
# 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
# . clear-stream(_test-tmp-stream)
# . . push args
68/push _test-tmp-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
# write(_test-stream, "cd")
# . . push args
68/push "cd"/imm32
68/push _test-stream/imm32
# . . call
e8/call write/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
# read a line from _test-stream into _test-tmp-stream
# . eax = read-line(_test-stream, _test-tmp-stream)
# . . push args
68/push _test-tmp-stream/imm32
68/push _test-stream/imm32
# . . call
e8/call read-line/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
# check-stream-equal(_test-tmp-stream, "cd", msg)
# . . push args
68/push "F - test-read-line-reads-final-line-until-Eof"/imm32
68/push "cd"/imm32
68/push _test-tmp-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