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| author | Kartik Agaram <vc@akkartik.com> | 2018-11-23 00:23:23 -0800 |
|---|---|---|
| committer | Kartik Agaram <vc@akkartik.com> | 2018-11-23 00:23:23 -0800 |
| commit | 886630e9376d0f8198117aac3c0d83938bb2c1c6 (patch) | |
| tree | 62ffaa3b3671159a8911c542b777f3c8f65b7768 /subx/059read-byte.subx | |
| parent | 4a99a6e0dd3000d8e595ec7b4b04f637e66ded6d (diff) | |
| download | mu-886630e9376d0f8198117aac3c0d83938bb2c1c6.tar.gz | |
4762
Diffstat (limited to 'subx/059read-byte.subx')
| -rw-r--r-- | subx/059read-byte.subx | 13 |
1 files changed, 8 insertions, 5 deletions
diff --git a/subx/059read-byte.subx b/subx/059read-byte.subx index fe915f49..e2b53d59 100644 --- a/subx/059read-byte.subx +++ b/subx/059read-byte.subx @@ -51,9 +51,9 @@ read-byte: # f : (address buffered-file) -> byte/EAX 56/push-ESI # ESI = f 8b/copy 1/mod/*+disp8 4/rm32/sib 5/base/EBP 4/index/none . 6/r32/ESI 8/disp8 . # copy *(EBP+8) to ESI - # ECX = f.read + # ECX = f->read 8b/copy 1/mod/*+disp8 6/rm32/ESI . . . 1/r32/ECX 8/disp8 . # copy *(ESI+8) to ECX - ## if (f.read < f.write) read byte from stream + ## if (f->read < f->write) read byte from stream 3b/compare 1/mod/*+disp8 6/rm32/ESI . . . 1/r32/ECX 4/disp8 . # compare ECX with *(ESI+4) 7c/jump-if-lesser $read-byte:from-stream/disp8 # clear-stream(stream = f+4) @@ -64,7 +64,7 @@ read-byte: # f : (address buffered-file) -> byte/EAX e8/call clear-stream/disp32 # discard args 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP - # EAX = read(f.fd, stream = f+4) + # EAX = read(f->fd, stream = f+4) # push args 50/push-EAX ff 6/subop/push 0/mod/indirect 6/rm32/ESI . . . . . . # push *ESI @@ -78,10 +78,10 @@ read-byte: # f : (address buffered-file) -> byte/EAX b8/copy-to-EAX 0xffffffff/imm32 eb/jump $read-byte:end/disp8 $read-byte:from-stream: - # AL = f.data[f.read] + # 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 *(ESI+ECX+16) to AL - # ++f.read + # ++f->read ff 0/subop/increment 1/mod/*+disp8 6/rm32/ESI . . . . 8/disp8 . # increment *(ESI+8) $read-byte:end: # restore registers @@ -92,6 +92,9 @@ $read-byte:end: 5d/pop-to-EBP c3/return +# todo: how should write-byte look? What should it do when the output has no +# space remaining? Maybe return an error code. + ## tests test-read-byte-single: |