diff options
Diffstat (limited to 'linux/122read-line.subx')
| -rw-r--r-- | linux/122read-line.subx | 385 |
1 files changed, 385 insertions, 0 deletions
diff --git a/linux/122read-line.subx b/linux/122read-line.subx new file mode 100644 index 00000000..02dcc0fd --- /dev/null +++ b/linux/122read-line.subx @@ -0,0 +1,385 @@ +== 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: (addr buffered-file), s: (addr stream byte) + # pseudocode: + # while true + # if (s->write >= s->size) 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->size) abort + 3b/compare 1/mod/*+disp8 7/rm32/edi . . . 2/r32/edx 8/disp8 . # compare edx with *(edi+8) + 7d/jump-if->= $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-< $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-= $read-line-buffered:end/disp8 +$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/newline + 75/jump-if-!= $read-line-buffered:loop/disp8 +$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 + +$read-line-buffered:abort: + # . _write(2/stderr, error) + # . . push args + 68/push "read-line-buffered: line too long\n"/imm32 + 68/push 2/imm32/stderr + # . . call + e8/call _write/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp + # . syscall(exit, 1) + bb/copy-to-ebx 1/imm32 + e8/call syscall_exit/disp32 + # never gets here + +test-read-line-buffered: + # - check that read-line-buffered stops at a newline + # setup + # . clear-stream(_test-stream) + # . . push args + 68/push _test-stream/imm32 + # . . call + e8/call clear-stream/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp + # . clear-stream($_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: (addr stream byte), s: (addr stream byte) + # pseudocode: + # while true + # if (s->write >= s->size) 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->size) abort + 3b/compare 1/mod/*+disp8 7/rm32/edi . . . 2/r32/edx 8/disp8 . # compare edx with *(edi+8) + 0f 8d/jump-if->= $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->= $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/newline + 0f 85/jump-if-!= $read-line:loop/disp32 +$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 + e8/call syscall_exit/disp32 + # 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 |