diff options
Diffstat (limited to '070new-stream.subx')
| -rw-r--r-- | 070new-stream.subx | 118 |
1 files changed, 118 insertions, 0 deletions
diff --git a/070new-stream.subx b/070new-stream.subx new file mode 100644 index 00000000..c3f204d2 --- /dev/null +++ b/070new-stream.subx @@ -0,0 +1,118 @@ +# Helper to allocate a stream on the heap. + +== 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 + +new-stream: # ad : (address allocation-descriptor), length : int, elemsize : int -> address/eax + # . prolog + 55/push-ebp + 89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp + # . save registers + 52/push-edx + # n = elemsize * length + 12 (for read, write and length) + # . eax = elemsize + 8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 0/r32/eax 0x10/disp8 . # copy *(ebp+16) to eax + # . eax *= length + 31/xor 3/mod/direct 2/rm32/edx . . . 2/r32/edx . . # clear edx + f7 4/subop/multiply 1/mod/*+disp8 5/rm32/ebp . . 0xc/disp8 . # multiply *(ebp+12) into eax + # . if overflow abort + 81 7/subop/compare 3/mod/direct 2/rm32/edx . . . . . 0/imm32 # compare edx + 75/jump-if-not-equal $new-stream:abort/disp8 + # . edx = elemsize*length + 89/copy 3/mod/direct 2/rm32/edx . . . 0/r32/eax . . # copy eax to edx + # . eax += 12 + 05/add-to-eax 0xc/imm32 + # allocate(ad, n) + # . . push args + 50/push-eax + ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 8/disp8 . # push *(ebp+8) + # . . call + e8/call allocate/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp + # eax->length = elemsize*length + 89/copy 1/mod/*+disp8 0/rm32/eax . . . 2/r32/edx 8/disp8 . # copy edx to *(eax+8) + # clear-stream(eax) + # . . push args + 50/push-eax + # . . call + e8/call clear-stream/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp +$new-stream:end: + # . restore registers + 5a/pop-to-edx + # . epilog + 89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp + 5d/pop-to-ebp + c3/return + +$new-stream:abort: + # . _write(2/stderr, error) + # . . push args + 68/push "new-stream: size too large\n"/imm32 + 68/push 2/imm32/stderr + # . . call + e8/call _write/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp + # . syscall(exit, 1) + bb/copy-to-ebx 1/imm32 + b8/copy-to-eax 1/imm32/exit + cd/syscall 0x80/imm8 + # never gets here + +test-new-stream: + # . prolog + 55/push-ebp + 89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp + # var heap/ecx : (address allocation-descriptor) = {0, 0} + 68/push 0/imm32/limit + 68/push 0/imm32/curr + 89/copy 3/mod/direct 1/rm32/ecx . . . 4/r32/esp . . # copy esp to ecx + # heap = new-segment(512) + # . . push args + 51/push-ecx + 68/push 0x200/imm32 + # . . call + e8/call new-segment/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp + # var start/edx = ad->curr + 8b/copy 0/mod/indirect 1/rm32/ecx . . . 2/r32/edx . . # copy *ecx to edx + # eax = new-stream(heap, 3, 2) + # . . push args + 68/push 2/imm32 + 68/push 3/imm32 + 51/push-ecx + # . . call + e8/call new-stream/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp + # check-ints-equal(eax, edx, msg) + # . . push args + 68/push "F - test-new-stream: returns current pointer of allocation descriptor"/imm32 + 52/push-edx + 50/push-eax + # . . call + e8/call check-ints-equal/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp + # check-ints-equal(eax->length, 6, msg) + # . . push args + 68/push "F - test-new-stream: sets length correctly"/imm32 + 68/push 6/imm32 + ff 6/subop/push 1/mod/*+disp8 0/rm32/eax . . . . . 8/disp8 # push *(eax+8) + # . . call + e8/call check-ints-equal/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp + # the rest is delegated to clear-stream() so we won't bother checking it + # . epilog + 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 |