diff options
Diffstat (limited to 'subx/059read-byte.subx')
| -rw-r--r-- | subx/059read-byte.subx | 41 |
1 files changed, 23 insertions, 18 deletions
diff --git a/subx/059read-byte.subx b/subx/059read-byte.subx index 39d818f4..b020442b 100644 --- a/subx/059read-byte.subx +++ b/subx/059read-byte.subx @@ -52,10 +52,11 @@ read-byte: # f : (address buffered-file) -> byte/EAX 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 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) + # otherwise first populate stream from file + # . 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 @@ -63,7 +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 @@ -77,6 +78,7 @@ read-byte: # f : (address buffered-file) -> byte/EAX b8/copy-to-EAX 0xffffffff/imm32 eb/jump $read-byte:end/disp8 $read-byte:from-stream: + # reading 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 *(ESI+ECX+16) to AL @@ -94,18 +96,19 @@ $read-byte:end: # todo: how should write-byte look? What should it do when the output has no # space remaining? Maybe return an error code. -## tests +# - tests test-read-byte-single: - ## check that read-byte returns first byte of 'file' - # clear-stream(_test-stream) + # - check that read-byte returns first byte of 'file' + # 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) + # . clear-stream(_test-buffered-file+4) # . . push args b8/copy-to-EAX _test-buffered-file/imm32 05/add-to-EAX 4/imm32 @@ -114,7 +117,7 @@ test-read-byte-single: 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") + # . write(_test-stream, "Ab") # . . push args 68/push "Ab"/imm32 68/push _test-stream/imm32 @@ -138,19 +141,20 @@ test-read-byte-single: e8/call check-ints-equal/disp32 # . . discard args 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add to ESP - # end + # . end c3/return test-read-byte-multiple: - ## call read-byte twice, check that second call returns second byte - # clear-stream(_test-stream) + # - call read-byte twice, check that second call returns second byte + # 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) + # . clear-stream(_test-buffered-file+4) # . . push args b8/copy-to-EAX _test-buffered-file/imm32 05/add-to-EAX 4/imm32 @@ -159,7 +163,7 @@ test-read-byte-multiple: 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") + # . write(_test-stream, "Ab") # . . push args 68/push "Ab"/imm32 68/push _test-stream/imm32 @@ -190,19 +194,20 @@ test-read-byte-multiple: e8/call check-ints-equal/disp32 # . . discard args 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add to ESP - # end + # . end c3/return test-read-byte-end-of-file: - ## call read-byte on an empty 'file', check that it returns -1 - # clear-stream(_test-stream) + # - call read-byte on an empty 'file', check that it returns -1 + # 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) + # . clear-stream(_test-buffered-file+4) # . . push args b8/copy-to-EAX _test-buffered-file/imm32 05/add-to-EAX 4/imm32 @@ -227,7 +232,7 @@ test-read-byte-end-of-file: e8/call check-ints-equal/disp32 # . . discard args 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add to ESP - # end + # . end c3/return == data |