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| author | Kartik Agaram <vc@akkartik.com> | 2020-07-05 12:13:28 -0700 |
|---|---|---|
| committer | Kartik Agaram <vc@akkartik.com> | 2020-07-05 12:13:28 -0700 |
| commit | c09c91e185aad8e01b570c2569e13c1e429d2f99 (patch) | |
| tree | 52a5ae1494ad5b7b2319411815dc45510e761c24 /050_write.subx | |
| parent | f2c5b05374186f9422cfdaf1ada096e39ac91a8b (diff) | |
| download | mu-c09c91e185aad8e01b570c2569e13c1e429d2f99.tar.gz | |
6612 - reorganize layers
Diffstat (limited to '050_write.subx')
| -rw-r--r-- | 050_write.subx | 53 |
1 files changed, 0 insertions, 53 deletions
diff --git a/050_write.subx b/050_write.subx deleted file mode 100644 index 2567f444..00000000 --- a/050_write.subx +++ /dev/null @@ -1,53 +0,0 @@ -# _write: write to a file descriptor (fd) - -== 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: # just exit; can't test _write just yet - bb/copy-to-ebx 0/imm32 - e8/call syscall_exit/disp32 - -_write: # fd: int, s: (addr array byte) - # . 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 - 53/push-ebx - # syscall(write, fd, (data) s+4, (size) *s) - # . ebx = fd - 8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 3/r32/ebx 8/disp8 . # copy *(ebp+8) to ebx - # . var data/ecx: (addr byte) = s+4 - 8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 1/r32/ecx 0xc/disp8 . # copy *(ebp+12) to ecx - 81 0/subop/add 3/mod/direct 1/rm32/ecx . . . . . 4/imm32 # add to ecx - # . var size/edx: int = *s - 8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 2/r32/edx 0xc/disp8 . # copy *(ebp+12) to edx - 8b/copy 0/mod/indirect 2/rm32/edx . . . 2/r32/edx . . # copy *edx to edx - # . syscall - e8/call syscall_write/disp32 - # if (eax < 0) abort - 3d/compare-eax-with 0/imm32 - 0f 8c/jump-if-< $_write:abort/disp32 -$_write:end: - # . restore registers - 5b/pop-to-ebx - 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 - -$_write:abort: - # can't write a message here for risk of an infinite loop, so we'll use a special exit code instead - # . syscall(exit, 255) - bb/copy-to-ebx 0xff/imm32 - e8/call syscall_exit/disp32 - # never gets here - -# . . vim:nowrap:textwidth=0 |