# some common helpers shared by phases of the SubX converter == 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 # (re)compute the bounds of the next word in the line # return empty string on reaching end of file next-word: # line : (address stream byte), out : (address slice) # . 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 56/push-ESI 57/push-EDI # ESI = line 8b/copy 1/mod/*+disp8 5/rm32/EBP . . . 6/r32/ESI 8/disp8 . # copy *(EBP+8) to ESI # EDI = out 8b/copy 1/mod/*+disp8 5/rm32/EBP . . . 7/r32/EDI 0xc/disp8 . # copy *(EBP+12) to EDI # skip-chars-matching(line, ' ') # . . push args 68/push 0x20/imm32/space ff 6/subop/push 1/mod/*+disp8 5/rm32/EBP . . . . 8/disp8 . # push *(EBP+8) # . . call e8/call skip-chars-matching/disp32 # . . discard args 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP $next-word:check0: # if (line->read >= line->write) clear out and return # . EAX = line->read 8b/copy 1/mod/*+disp8 6/rm32/ESI . . . 0/r32/EAX 4/disp8 . # copy *(ESI+4) to EAX # . if (EAX < line->write) goto next check 3b/compare 0/mod/indirect 6/rm32/ESI . . . 0/r32/EAX . . # compare EAX with *ESI 7c/jump-if-lesser $next-word:check1/disp8 # . return out = {0, 0} c7 0/subop/copy 0/mod/direct 7/rm32/EDI . . . . . 0/imm32 # copy to *EDI c7 0/subop/copy 1/mod/*+disp8 7/rm32/EDI . . . . 4/disp8 0/imm32 # copy to *(EDI+4) eb/jump $next-word:end/disp8 $next-word:check1: # out->start = &line->data[line->read] 8b/copy 1/mod/*+disp8 6/rm32/ESI . . . 1/r32/ECX 4/disp8 . # copy *(ESI+4) to ECX 8d/copy-address 1/mod/*+disp8 4/rm32/sib 6/base/ESI 1/index/ECX . 0/r32/EAX 0xc/disp8 . # copy ESI+ECX+12 to EAX 89/copy 0/mod/indirect 7/rm32/EDI . . . 0/r32/EAX . . # copy EAX to *EDI # if (line->data[line->read] == '#') out->end = &line->data[line->write]), skip rest of stream and return # . EAX = line->data[line->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 0xc/disp8 . # copy byte at *(ESI+ECX+12) to AL # . compare 3d/compare-EAX-and 0x23/imm32/pound 75/jump-if-not-equal $next-word:not-comment/disp8 # . out->end = &line->data[line->write] 8b/copy 0/mod/indirect 6/rm32/ESI . . . 0/r32/EAX . . # copy *ESI to EAX 8d/copy-address 1/mod/*+disp8 4/rm32/sib 6/base/ESI 0/index/EAX . 0/r32/EAX 0xc/disp8 . # copy ESI+EAX+12 to EAX 89/copy 1/mod/*+disp8 7/rm32/EDI . . . 0/r32/EAX 4/disp8 . # copy EAX to *(EDI+4) # . line->read = line->write 89/copy 1/mod/*+disp8 6/rm32/ESI . . . 0/r32/EAX 4/disp8 . # copy EAX to *(ESI+4) # . return eb/jump $next-word:end/disp8 $next-word:not-comment: # otherwise skip-chars-not-matching-whitespace(line) # including trailing newline # . . push args ff 6/subop/push 1/mod/*+disp8 5/rm32/EBP . . . . 8/disp8 . # push *(EBP+8) # . . call e8/call skip-chars-not-matching-whitespace/disp32 # . . discard args 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP # out->end = &line->data[line->read] 8b/copy 1/mod/*+disp8 6/rm32/ESI . . . 1/r32/ECX 4/disp8 . # copy *(ESI+4) to ECX 8d/copy-address 1/mod/*+disp8 4/rm32/sib 6/base/ESI 1/index/ECX . 0/r32/EAX 0xc/disp8 . # copy ESI+ECX+12 to EAX 89/copy 1/mod/*+disp8 7/rm32/EDI . . . 0/r32/EAX 4/disp8 . # copy EAX to *(EDI+4) $next-word:end: # . restore registers 5f/pop-to-EDI 5e/pop-to-ESI 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 test-next-word: # . prolog 55/push-EBP 89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP # 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 # var slice/ECX = {0, 0} 68/push 0/imm32/end 68/push 0/imm32/start 89/copy 3/mod/direct 1/rm32/ECX . . . 4/r32/ESP . . # copy ESP to ECX # write(_test-stream, " ab") # . . push args 68/push " ab"/imm32 68/push _test-stream/imm32 # . . call e8/call write/disp32 # . . discard args 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP # next-word(_test-stream, slice) # . . push args 51/push-ECX 68/push _test-stream/imm32 # . . call e8/call next-word/disp32 # . . discard args 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP # check-ints-equal(slice->start - _test-stream->data, 2, msg) # . check-ints-equal(slice->start - _test-stream, 14, msg) # . . push args 68/push "F - test-next-word: start"/imm32 68/push 0xe/imm32 # . . push slice->start - _test-stream 8b/copy 0/mod/indirect 1/rm32/ECX . . . 0/r32/EAX . . # copy *ECX to EAX 81 5/subop/subtract 3/mod/direct 0/rm32/EAX . . . . . _test-stream/imm32 # subtract from EAX 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(slice->end - _test-stream->data, 4, msg) # . check-ints-equal(slice->end - _test-stream, 16, msg) # . . push args 68/push "F - test-next-word: end"/imm32 68/push 0x10/imm32 # . . push slice->end - _test-stream 8b/copy 1/mod/*+disp8 1/rm32/ECX . . . 0/r32/EAX 4/disp8 . # copy *(ECX+4) to EAX 81 5/subop/subtract 3/mod/direct 0/rm32/EAX . . . . . _test-stream/imm32 # subtract from EAX 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 # . epilog 89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP 5d/pop-to-EBP c3/return test-next-word-returns-whole-comment: # . prolog 55/push-EBP 89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP # 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 # var slice/ECX = {0, 0} 68/push 0/imm32/end 68/push 0/imm32/start 89/copy 3/mod/direct 1/rm32/ECX . . . 4/r32/ESP . . # copy ESP to ECX # write(_test-stream, " # a") # . . push args 68/push " # a"/imm32 68/push _test-stream/imm32 # . . call e8/call write/disp32 # . . discard args 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP # next-word(_test-stream, slice) # . . push args 51/push-ECX 68/push _test-stream/imm32 # . . call e8/call next-word/disp32 # . . discard args 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP # check-ints-equal(slice->start - _test-stream->data, 2, msg) # . check-ints-equal(slice->start - _test-stream, 14, msg) # . . push args 68/push "F - test-next-word-returns-whole-comment: start"/imm32 68/push 0xe/imm32 # . . push slice->start - _test-stream 8b/copy 0/mod/indirect 1/rm32/ECX . . . 0/r32/EAX . . # copy *ECX to EAX 81 5/subop/subtract 3/mod/direct 0/rm32/EAX . . . . . _test-stream/imm32 # subtract from EAX 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(slice->end - _test-stream->data, 5, msg) # . check-ints-equal(slice->end - _test-stream, 17, msg) # . . push args 68/push "F - test-next-word-returns-whole-comment: end"/imm32 68/push 0x11/imm32 # . . push slice->end - _test-stream 8b/copy 1/mod/*+disp8 1/rm32/ECX . . . 0/r32/EAX 4/disp8 . # copy *(ECX+4) to EAX 81 5/subop/subtract 3/mod/direct 0/rm32/EAX . . . . . _test-stream/imm32 # subtract from EAX 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 # . epilog 89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP 5d/pop-to-EBP c3/return test-next-word-returns-empty-string-on-eof: # . prolog 55/push-EBP 89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP # 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 # var slice/ECX = {0, 0} 68/push 0/imm32/end 68/push 0/imm32/start 89/copy 3/mod/direct 1/rm32/ECX . . . 4/r32/ESP . . # copy ESP to ECX # write nothing to _test-stream # next-word(_test-stream, slice) # . . push args 51/push-ECX 68/push _test-stream/imm32 # . . call e8/call next-word/disp32 # . . discard args 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP # check-ints-equal(slice->end - slice->start, 0, msg) # . . push args 68/push "F - test-next-word-returns-empty-string-on-eof"/imm32 68/push 0/imm32 # . . push slice->end - slice->start 8b/copy 1/mod/*+disp8 1/rm32/ECX . . . 0/r32/EAX 4/disp8 . # copy *(ECX+4) to EAX 2b/subtract 0/mod/indirect 1/rm32/ECX . . . 0/r32/EAX . . # subtract *ECX from EAX 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 # . epilog 89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP 5d/pop-to-EBP c3/return