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| author | Kartik K. Agaram <vc@akkartik.com> | 2021-10-13 23:15:59 -0700 |
|---|---|---|
| committer | Kartik K. Agaram <vc@akkartik.com> | 2021-10-13 23:15:59 -0700 |
| commit | 9a183b817903c39fc33d38d73bf506ced3e5553e (patch) | |
| tree | bfa090e6815c1963dc1583397ee68349fa6b571c /115write-byte.subx | |
| parent | db0363462f42b05561853bd295fb4d39909a9f6c (diff) | |
| download | mu-9a183b817903c39fc33d38d73bf506ced3e5553e.tar.gz | |
support backspace when reading line from keyboard
Diffstat (limited to '115write-byte.subx')
| -rw-r--r-- | 115write-byte.subx | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/115write-byte.subx b/115write-byte.subx index 67516731..0df1b85e 100644 --- a/115write-byte.subx +++ b/115write-byte.subx @@ -76,4 +76,29 @@ test-append-byte-single: # . end c3/return +undo-append-byte: # f: (addr stream 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 + # eax = f + 8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 0/r32/eax 8/disp8 . # copy *(ebp+8) to eax + # if (f->write <= 0) abort + 81 7/subop/compare 0/mod/indirect 0/rm32/eax . . . . . 0/imm32 # compare *eax + 7e/jump-if-<= $undo-append-byte:abort/disp8 + # --f->write + ff 1/subop/decrement 0/mod/indirect 0/rm32/eax . . . . . . # decrement *eax +$undo-append-byte:end: + # . restore registers + 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 + +$undo-append-byte:abort: + (abort "undo-append-byte: empty stream") + # never gets here + # . . vim:nowrap:textwidth=0 |