diff options
Diffstat (limited to 'baremetal/108write.subx')
| -rw-r--r-- | baremetal/108write.subx | 53 |
1 files changed, 53 insertions, 0 deletions
diff --git a/baremetal/108write.subx b/baremetal/108write.subx new file mode 100644 index 00000000..daf1f535 --- /dev/null +++ b/baremetal/108write.subx @@ -0,0 +1,53 @@ +# 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 + +write: # f: (addr stream byte), s: (addr array byte) + # . prologue + 55/push-ebp + 89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp + # if (s == 0) return + 81 7/subop/compare 1/mod/*+disp8 5/rm32/ebp . . . . 0xc/disp8 0/imm32 # compare *(ebp+12) + 74/jump-if-= $write:end/disp8 + # TODO: write to file + # otherwise, treat 'f' as a stream to append to + # . save registers + 50/push-eax + 51/push-ecx + 52/push-edx + 53/push-ebx + # ecx = f + 8b/copy 1/mod/*+disp8 5/rm32/ebp . . 1/r32/ecx 8/disp8 . # copy *(ebp+8) to ecx + # edx = f->write + 8b/copy 0/mod/indirect 1/rm32/ecx . . . 2/r32/edx . . # copy *ecx to edx + # ebx = f->size + 8b/copy 1/mod/*+disp8 1/rm32/ecx . . . 3/r32/ebx 8/disp8 . # copy *(ecx+8) to ebx + # eax = _append-3(&f->data[f->write], &f->data[f->size], s) + # . . push s + ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 0xc/disp8 . # push *(ebp+12) + # . . push &f->data[f->size] + 8d/copy-address 1/mod/*+disp8 4/rm32/sib 1/base/ecx 3/index/ebx . 3/r32/ebx 0xc/disp8 . # copy ecx+ebx+12 to ebx + 53/push-ebx + # . . push &f->data[f->write] + 8d/copy-address 1/mod/*+disp8 4/rm32/sib 1/base/ecx 2/index/edx . 3/r32/ebx 0xc/disp8 . # copy ecx+edx+12 to ebx + 53/push-ebx + # . . call + e8/call _append-3/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp + # f->write += eax + 01/add 0/mod/indirect 1/rm32/ecx . . . 0/r32/eax . . # add eax to *ecx + # . restore registers + 5b/pop-to-ebx + 5a/pop-to-edx + 59/pop-to-ecx + 58/pop-to-eax +$write:end: + # . epilogue + 89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp + 5d/pop-to-ebp + c3/return + +# TODO: bring in tests once we have check-ints-equal + +# . . vim:nowrap:textwidth=0 |