diff options
Diffstat (limited to 'subx/056write.subx')
| -rw-r--r-- | subx/056write.subx | 107 |
1 files changed, 27 insertions, 80 deletions
diff --git a/subx/056write.subx b/subx/056write.subx index f8e32fb2..c9303b56 100644 --- a/subx/056write.subx +++ b/subx/056write.subx @@ -33,7 +33,6 @@ Test-ostream: # 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: (manual test if this is the last file loaded) -#? e8/call test-write-appends/disp32 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 . . 1/r32/EBX Num-test-failures/disp32 # copy *Num-test-failures to EBX @@ -44,12 +43,6 @@ write: # f : fd or (address stream), s : (address array byte) -> <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 - 52/push-EDX - 53/push-EBX - 56/push-ESI # if (f < 0x08000000) _write(f, s), return # f can't be a user-mode address, so treat it as a kernel file descriptor 81 7/subop/compare 1/mod/*+disp8 4/rm32/sib 5/base/EBP 4/index/none . . 8/disp8 0x08000000/imm32 # compare *(EBP+8) 7f/jump-if-greater $write:else/disp8 @@ -63,84 +56,38 @@ write: # f : fd or (address stream), s : (address array byte) -> <void> eb/jump $write:end/disp8 $write:else: # otherwise, treat 'f' as a stream to append to - # - # pseudocode: - # destend = &f.data[t.length] - # oldw = f.write - # if s.length == 0 return - # f.write += s.length - # dest = &f.data[oldw] - # srcend = &s.data[s.length] - # src = &s.data[0] - # while true: - # if src >= srcend break - # if dest >= destend break # for now silently ignore filled up ostream buffer - # *dest = *src - # ++src - # ++dest - # - # key registers to set up for the loop: - # EAX/dest, ECX/destend, EBX/src, ESI/srcend - # we save EDX for byte operations (has to be one of the first 4 registers) - # - # register setup before the loop: - # EAX = *(EBP+8) # f - # EBX = *(EBP+12) # s - # ECX = *(EAX+4) # f.length - # ECX = EAX+8+ECX # destend = &f.data[f.length] - # ESI = *EAX # oldw = f.write - # EDX = *EBX # s.length - # *EAX = *EAX + EDX # update f.write (allowed to go past f.length) - # # do this here just because it's convenient - # EAX = EAX+8+ESI # dest = &f.data[oldw] - # ESI = EBX+4+EDX # srcend = &s.data[s.length] - # EBX = EBX+4 # src = &s.data[0] - # - # EAX = f - 8b/copy 1/mod/*+disp8 4/rm32/sib 5/base/EBP 4/index/none 0/r32/EAX 8/disp8 . # copy *(EBP+8) to EAX - # EBX = s - 8b/copy 1/mod/*+disp8 4/rm32/sib 5/base/EBP 4/index/none 3/r32/EBX 0xc/disp8 . # copy *(EBP+12) to EBX - # ECX = f.length - 8b/copy 1/mod/*+disp8 0/rm32/EAX . . . 1/r32/ECX 4/disp8 . # copy *(EAX+4) to ECX - # ECX/destend = &f.data[f.length] - 8d/copy-address 1/mod/*+disp8 4/rm32/sib 0/base/EAX 1/index/ECX . 1/r32/ECX 8/disp8 . # copy EAX+ECX+8 to ECX - # ESI/oldw = f.write - 8b/copy 0/mod/indirect 0/rm32/EAX . . . 6/r32/ESI . . # copy *EAX to ESI - # EDX = s.length - 8b/copy 0/mod/indirect 3/rm32/EBX . . . 2/r32/EDX . . # copy *EBX to EDX - # if EDX == 0 return - 81 7/subop/compare 3/mod/direct 2/rm32/EDX . . . . . 0/imm32 # compare EDX - 74/jump-if-equal $write:end/disp8 - # f.write += s.length - 01/add 0/mod/indirect 0/rm32/EAX . . . 2/r32/EDX . . # add EDX to *EAX - # EAX/dest = &f.data[oldw] - 8d/copy-address 1/mod/*+disp8 4/rm32/sib 0/base/EAX 6/index/ESI . 0/r32/EAX 8/disp8 . # copy EAX+ESI+8 to EAX - # ESI/srcend = &s.data[s.length] - 8d/copy-address 1/mod/*+disp8 4/rm32/sib 3/base/EBX 2/index/EDX . 6/r32/ESI 4/disp8 . # copy EBX+EDX+4 to ESI - # EBX/src = &s.data[0] - 81 0/subop/add 3/mod/direct 3/rm32/EBX . . . . . 4/imm32 # add to EBX - # while (true) -$write:loop: - # if EBX/src >= ESI/srcend break - 39/compare 3/mod/direct 3/rm32/EBX . . . 6/r32/ESI . . # compare EBX with ESI - 7d/jump-if-greater-or-equal $write:end/disp8 - # if EAX/dest >= ECX/destend break (for now silently ignore filled up ostream buffer) - 39/compare 3/mod/direct 0/rm32/EAX . . . 1/r32/ECX . . # compare EAX with ECX - 7d/jump-if-greater-or-equal $write:end/disp8 - # copy one byte - 8a/copy-byte 0/mod/indirect 3/rm32/EBX . . . 2/r32/DL . . # copy byte at *EBX to DL - 88/copy-byte 0/mod/indirect 0/rm32/EAX . . . 2/r32/DL . . # copy byte at DL to *EAX - # updates - 40/increment-EAX - 43/increment-EBX - eb/jump $write:loop/disp8 -$write:end: + # save registers + 50/push-EAX + 51/push-ECX + 52/push-EDX + 53/push-EBX + # ECX = f + 8b/copy 1/mod/*+disp8 4/rm32/sib 5/base/EBP 4/index/none 1/r32/ECX 8/disp8 . # copy *(EBP+8) to ECX + # EDX = f.write + 8b/copy 0/mod/indirect 1/rm32/ECX . . . 2/r32/EDX . . # copy *ECX to EDX + # EBX = f.length + 8b/copy 1/mod/*+disp8 1/rm32/ECX . . . 3/r32/EBX 4/disp8 . # copy *(ECX+4) to EBX + # EAX = _append(&f.data[f.write], &f.data[f.length], s) + # push s + ff 6/subop/push 1/mod/*+disp8 4/rm32/sib 5/base/EBP 4/index/none . . 0xc/disp8 . # push *(EBP+12) + # push &f.data[f.length] + 8d/copy-address 1/mod/*+disp8 4/rm32/sib 1/base/ECX 3/index/EBX . 3/r32/EBX 8/disp8 . # copy ECX+EBX+8 to EBX + 53/push-EBX + # push &f.data[f.write] + 8d/copy-address 1/mod/*+disp8 4/rm32/sib 1/base/ECX 2/index/EDX . 3/r32/EBX 8/disp8 . # copy ECX+EBX+8 to EBX + 53/push-EBX + # call + e8/call _append/disp32 + # discard args + 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add to ESP + # f.write += EAX + 01/add 0/mod/indirect 1/rm32/ECX . . . 0/r32/EAX . . # add EAX to *ECX # restore registers - 5e/pop-to-ESI 5b/pop-to-EBX 5a/pop-to-EDX 59/pop-to-ECX 58/pop-to-EAX +$write:end: # epilog 89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP 5d/pop-to-EBP |