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| author | Kartik Agaram <vc@akkartik.com> | 2019-02-02 22:05:11 -0800 |
|---|---|---|
| committer | Kartik Agaram <vc@akkartik.com> | 2019-02-02 22:05:11 -0800 |
| commit | 03c6f1d3858ff0fdb6af6ce4b61bea51f16b33be (patch) | |
| tree | 2dfceaa7676f03f09dc3585030b56cdea834483d /subx/055stream.subx | |
| parent | cb82bd2364c302acbb96dd6900779e189b36efac (diff) | |
| download | mu-03c6f1d3858ff0fdb6af6ce4b61bea51f16b33be.tar.gz | |
4949
Diffstat (limited to 'subx/055stream.subx')
| -rw-r--r-- | subx/055stream.subx | 61 |
1 files changed, 61 insertions, 0 deletions
diff --git a/subx/055stream.subx b/subx/055stream.subx new file mode 100644 index 00000000..9711c60a --- /dev/null +++ b/subx/055stream.subx @@ -0,0 +1,61 @@ +# streams: data structure for operating on arrays in a stateful manner +# +# A stream looks like this: +# read : int # index that we've read until +# write : int # index at which writes go +# data : (array byte) # prefixed by length as usual +# +# primitives for operating on streams: +# - clear-stream (clears everything but the data length) +# - stream-equal? (compares stream data with a string; ignores read pointer) +# - rewind-reads (resets read pointer; not yet implemented) + +== 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 + +# main: + e8/call run-tests/disp32 # 'run-tests' is a function created automatically by SubX. It calls all functions that start with 'test-'. + # syscall(exit, Num-test-failures) + 8b/copy 0/mod/indirect 5/rm32/.disp32 . . 3/r32/EBX Num-test-failures/disp32 # copy *Num-test-failures to EBX + b8/copy-to-EAX 1/imm32/exit + cd/syscall 0x80/imm8 + +clear-stream: # f : (address stream) -> <void> + # . prolog + 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 + # EAX = f + 8b/copy 1/mod/*+disp8 5/rm32/EBP . . 0/r32/EAX 8/disp8 . # copy *(EBP+8) to EAX + # ECX = f->length + 8b/copy 1/mod/*+disp8 0/rm32/EAX . . . 1/r32/ECX 8/disp8 . # copy *(EAX+8) to ECX + # ECX = &f->data[f->length] + 8d/copy-address 1/mod/*+disp8 4/rm32/sib 0/base/EAX 1/index/ECX . 1/r32/ECX 0xc/disp8 . # copy EAX+ECX+12 to ECX + # f->write = 0 + c7 0/subop/copy 0/mod/direct 0/rm32/EAX . . . . . 0/imm32 # copy to *EAX + # f->read = 0 + c7 0/subop/copy 1/mod/*+disp8 0/rm32/EAX . . . . 4/disp8 0/imm32 # copy to *(EAX+4) + # EAX = f->data + 81 0/subop/add 3/mod/direct 0/rm32/EAX . . . . . 0xc/imm32 # add to EAX + # while (true) +$clear-stream:loop: + # if EAX >= ECX break + 39/compare 3/mod/direct 0/rm32/EAX . . . 1/r32/ECX . . # compare EAX with ECX + 7d/jump-if-greater-or-equal $clear-stream:end/disp8 + # *EAX = 0 + c6 0/subop/copy 0/mod/direct 0/rm32/EAX . . . . . 0/imm8 # copy byte to *EAX + # ++EAX + 40/increment-EAX + eb/jump $clear-stream:loop/disp8 +$clear-stream:end: + # . restore registers + 59/pop-to-ECX + 58/pop-to-EAX + # . epilog + 89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP + 5d/pop-to-EBP + c3/return |