== 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 # read bytes from 'f' until (and including) a newline and store them into 's' # return true if no data found, false otherwise # just abort if 's' is too small read-line: # f : (address buffered-file), s : (address stream byte) -> eof?/EAX # pseudocode: # loop: # if (s->write >= s->length) abort # if (f->read >= f->write) populate stream from file # if (f->write == 0) break # AL = f->data[f->read] # s->data[s->write] = AL # ++f->read # ++s->write # if AL == '\n' break # . prolog 55/push-EBP 89/copy 3/mod/direct 5/rm32/EBP . . . 4/r32/ESP . . # copy ESP to EBP # . save registers 51/push-ECX 52/push-EDX 56/push-ESI 57/push-EDI # ESI = f 8b/copy 1/mod/*+disp8 5/rm32/EBP . . . 6/r32/ESI 8/disp8 . # copy *(EBP+8) to ESI # ECX = f->read 8b/copy 1/mod/*+disp8 6/rm32/ESI . . . 1/r32/ECX 8/disp8 . # copy *(ESI+8) to ECX # EDI = s 8b/copy 1/mod/*+disp8 5/rm32/EBP . . . 7/r32/EDI 0xc/disp8 . # copy *(EBP+12) to EDI # EDX = s->write 8b/copy 0/mod/indirect 7/rm32/EDI . . . 2/r32/EDX . . # copy *EDI to EDX $read-line:loop: # if (s->write >= s->length) abort 3b/compare 1/mod/*+disp8 7/rm32/EDI . . . 2/r32/EDX 8/disp8 . # compare EDX with *(EDI+8) 7d/jump-if-greater-or-equal $read-line:abort/disp8 # if (f->read >= f->write) populate stream from file 3b/compare 1/mod/*+disp8 6/rm32/ESI . . . 1/r32/ECX 4/disp8 . # compare ECX with *(ESI+4) 7c/jump-if-lesser $read-line:from-stream/disp8 # . clear-stream(stream = f+4) # . . push args 8d/copy-address 1/mod/*+disp8 6/rm32/ESI . . . 0/r32/EAX 4/disp8 . # copy ESI+4 to EAX 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 # . f->read must now be 0; update its cache at ECX 31/xor 3/mod/direct 1/rm32/ECX . . . 1/r32/ECX . . # clear ECX # . EAX = read(f->fd, stream = f+4) # . . push args 50/push-EAX ff 6/subop/push 0/mod/indirect 6/rm32/ESI . . . . . . # push *ESI # . . call e8/call read/disp32 # . . discard args 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP # if f->write == 0 return true # . if EAX == 0 return true 81 7/subop/compare 3/mod/direct 0/rm32/EAX . . . . . 0/imm32 # compare EAX 75/jump-if-not-equal $read-line:from-stream/disp8 b8/copy-to-EAX 0xffffffff/imm32 eb/jump $read-line:end/disp8 $read-line:from-stream: # AL = f->data[f->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 0x10/disp8 . # copy byte at *(ESI+ECX+16) to AL # s->data[s->write] = AL 88/copy-byte 1/mod/*+disp8 4/rm32/sib 7/base/EDI 2/index/EDX . 0/r32/AL 0xc/disp8 . # copy AL to *(EDI+EDX+12) # ++f->read 41/increment-ECX # ++s->write 42/increment-EDX # if AL == '\n' return false 81 7/subop/compare 3/mod/direct 0/rm32/EAX . . . . . 0xa/imm32 # compare EAX 75/jump-if-not-equal $read-line:loop/disp8 31/xor 3/mod/direct 0/rm32/EAX . . . 0/r32/EAX . . # clear EAX $read-line:end: # save f->read 89/copy 1/mod/*+disp8 6/rm32/ESI . . . 1/r32/ECX 8/disp8 . # copy ECX to *(ESI+8) # save s->write 89/copy 0/mod/indirect 7/rm32/EDI . . . 2/r32/EDX . . # copy EDX to *EDI # . restore registers 5f/pop-to-EDI 5e/pop-to-ESI 5a/pop-to-EDX 59/pop-to-ECX # . epilog 89/copy 3/mod/direct 4/rm32/ESP . . . 5/r32/EBP . . # copy EBP to ESP 5d/pop-to-EBP c3/return $read-line:abort: # . _write(2/stderr, error) # . . push args 68/push "read-line: line too long"/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-read-line: # - check that read-line stops at a newline # 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 # . clear-stream(_test-buffered-file+4) # . . push args b8/copy-to-EAX _test-buffered-file/imm32 05/add-to-EAX 4/imm32 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 # . clear-stream(_test-stream-buffer) # . . push args 68/push _test-stream-buffer/imm32 # . . call e8/call clear-stream/disp32 # . . discard args 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP # write(_test-stream, "ab\ncd") # . 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 # . write(_test-stream, "\n") # . . push args 68/push Newline/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 # . write(_test-stream, "cd") # . . push args 68/push "cd"/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 # read a line from _test-stream (buffered by _test-buffered-file) into _test-stream-buffer # . EAX = read-line(_test-buffered-file, _test-stream-buffer) # . . push args 68/push _test-stream-buffer/imm32 68/push _test-buffered-file/imm32 # . . call e8/call read-line/disp32 # . . discard args 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP # check-ints-equal(EAX, 0/not-at-eof, msg) # . . push args 68/push "F - test-read-line: return value"/imm32 68/push 0/imm32/not-at-eof 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(*_test-stream-buffer->data, 61/a 62/b 0a/newline 00, msg) # . . push args 68/push "F - test-read-line"/imm32 68/push 0x000a6261/imm32 # . . push *_test-stream->data b8/copy-to-EAX _test-stream-buffer/imm32 ff 6/subop/push 1/mod/*+disp8 0/rm32/EAX . . . . 0xc/disp8 . # push *(EAX+12) # . . call e8/call check-ints-equal/disp32 # . . discard args 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add to ESP # end c3/return test-read-line-returns-true-on-eof: # 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 # . clear-stream(_test-buffered-file+4) # . . push args b8/copy-to-EAX _test-buffered-file/imm32 05/add-to-EAX 4/imm32 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 # . clear-stream(_test-stream-buffer) # . . push args 68/push _test-stream-buffer/imm32 # . . call e8/call clear-stream/disp32 # . . discard args 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP # write nothing # EAX = read-line(_test-buffered-file, _test-stream-buffer) # . . push args 68/push _test-stream-buffer/imm32 68/push _test-buffered-file/imm32 # . . call e8/call read-line/disp32 # . . discard args 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP # check-ints-equal(EAX, eof, msg) # . . push args 68/push "F - test-read-line-returns-true-on-eof"/imm32 68/push 0xffffffff/imm32/not-at-eof 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 # end c3/return test-read-line-reads-final-line-until-eof: # 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 # . clear-stream(_test-buffered-file+4) # . . push args b8/copy-to-EAX _test-buffered-file/imm32 05/add-to-EAX 4/imm32 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 # . clear-stream(_test-stream-buffer) # . . push args 68/push _test-stream-buffer/imm32 # . . call e8/call clear-stream/disp32 # . . discard args 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP # write(_test-stream, "cd") # . . push args 68/push "cd"/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 # read a line from _test-stream (buffered by _test-buffered-file) into _test-stream-buffer # . EAX = read-line(_test-buffered-file, _test-stream-buffer) # . . push args 68/push _test-stream-buffer/imm32 68/push _test-buffered-file/imm32 # . . call e8/call read-line/disp32 # . . discard args 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP # check-ints-equal(EAX, eof, msg) # . . push args 68/push "F - test-read-line-reads-final-line-until-eof: return value"/imm32 68/push 0xffffffff/imm32/not-at-eof 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(*_test-stream-buffer->data, 63/c 64/d 00 00, msg) # . . push args 68/push "F - test-read-line-reads-final-line-until-eof"/imm32 68/push 0x00006463/imm32 # . . push *_test-stream->data b8/copy-to-EAX _test-stream-buffer/imm32 ff 6/subop/push 1/mod/*+disp8 0/rm32/EAX . . . . 0xc/disp8 . # push *(EAX+12) # . . call e8/call check-ints-equal/disp32 # . . discard args 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add to ESP # end c3/return # . . vim:nowrap:textwidth=0