# 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