diff options
| 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 /106stream.subx | |
| parent | f2c5b05374186f9422cfdaf1ada096e39ac91a8b (diff) | |
| download | mu-c09c91e185aad8e01b570c2569e13c1e429d2f99.tar.gz | |
6612 - reorganize layers
Diffstat (limited to '106stream.subx')
| -rw-r--r-- | 106stream.subx | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/106stream.subx b/106stream.subx new file mode 100644 index 00000000..84d0580b --- /dev/null +++ b/106stream.subx @@ -0,0 +1,74 @@ +# streams: data structure for operating on arrays in a stateful manner +# +# A stream looks like this: +# write: int # index at which writes go +# read: int # index that we've read until +# data: (array byte) # prefixed by size as usual +# +# some primitives for operating on streams: +# - clear-stream (clears everything but the data size) +# - rewind-stream (resets read pointer) + +== 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 + +clear-stream: # 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 + 51/push-ecx + # eax = f + 8b/copy 1/mod/*+disp8 5/rm32/ebp . . 0/r32/eax 8/disp8 . # copy *(ebp+8) to eax + # var count/ecx: int = f->size + 8b/copy 1/mod/*+disp8 0/rm32/eax . . . 1/r32/ecx 8/disp8 . # copy *(eax+8) to ecx + # var max/ecx: (addr byte) = &f->data[f->size] + 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) + # - clear all stream data + # - this isn't strictly necessary, and it can slow things down *a lot*, but better safe than sorry. + # var curr/eax: (addr byte) = f->data + 81 0/subop/add 3/mod/direct 0/rm32/eax . . . . . 0xc/imm32 # add to eax +$clear-stream:loop: + # if (curr >= max) break + 39/compare 3/mod/direct 0/rm32/eax . . . 1/r32/ecx . . # compare eax with ecx + 73/jump-if-addr>= $clear-stream:end/disp8 + # *curr = 0 + c6 0/subop/copy-byte 0/mod/direct 0/rm32/eax . . . . . 0/imm8 # copy byte to *eax + # ++curr + 40/increment-eax + eb/jump $clear-stream:loop/disp8 +$clear-stream:end: + # . restore registers + 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 + +rewind-stream: # 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 + # f->read = 0 + c7 0/subop/copy 1/mod/*+disp8 0/rm32/eax . . . . 4/disp8 0/imm32 # copy to *(eax+4) +$rewind-stream: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 + +# . . vim:nowrap:textwidth=0 |