diff options
Diffstat (limited to 'subx/077slurp.subx')
| -rw-r--r-- | subx/077slurp.subx | 161 |
1 files changed, 161 insertions, 0 deletions
diff --git a/subx/077slurp.subx b/subx/077slurp.subx new file mode 100644 index 00000000..2bf203da --- /dev/null +++ b/subx/077slurp.subx @@ -0,0 +1,161 @@ +== 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 all bytes from 'f' and store them into 's' +# abort if 's' is too small +slurp: # f : (address buffered-file), s : (address stream byte) -> <void> + # 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 + # . prolog + 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 +$slurp: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 $slurp: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 $slurp: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 $slurp:end/disp8 +$slurp: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 + eb/jump $slurp:loop/disp8 +$slurp: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 + # . epilog + 89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP + 5d/pop-to-EBP + c3/return + +$slurp:abort: + # . _write(2/stderr, error) + # . . push args + 68/push "slurp: destination too small\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-slurp: + # 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+4) + # . . push args + b8/copy-to-EAX _test-buffered-file/imm32 + 05/add-to-EAX 4/imm32 + 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 + # . 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 = slurp(_test-buffered-file, _test-tmp-stream) + # . . push args + 68/push _test-tmp-stream/imm32 + 68/push _test-buffered-file/imm32 + # . . call + e8/call slurp/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP + # check-stream-equal(_test-tmp-stream, "ab\ncd", msg) + # . . push args + 68/push "F - test-slurp"/imm32 + 68/push "ab\ncd"/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 |