# Tokenize by whitespace.

== 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 (surrounded by whitespace,
# treating '#' comments as a single word)
# return empty string on reaching end of file
next-word:  # line: (addr stream byte), out: (addr slice)
    # . prologue
    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-whitespace(line)
    # . . push args
    ff          6/subop/push        1/mod/*+disp8   5/rm32/ebp    .           .             .           .           8/disp8         .                 # push *(ebp+8)
    # . . call
    e8/call  skip-chars-matching-whitespace/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/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-<  $next-word:check-for-comment/disp8
    # . return out
    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:check-for-comment:
    # 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-!=  $next-word:regular-word/disp8
$next-word:comment:
    # . 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
    8b/copy                         0/mod/indirect  6/rm32/esi    .           .             .           0/r32/eax   .               .                 # copy *esi to eax
    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:regular-word:
    # 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
    # . epilogue
    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
    5d/pop-to-ebp
    c3/return

test-next-word:
    # . prologue
    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: slice
    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
    # . epilogue
    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:
    # . prologue
    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: slice
    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
    # . epilogue
    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:
    # . prologue
    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: slice
    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
    # . epilogue
    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-newline:
    # . prologue
    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: slice
    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 some whitespace and a newline
    # . . push args
    68/push  "  \n"/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->end - slice->start, 0, msg)
    # . . push args
    68/push  "F - test-next-word-returns-empty-string-on-newline"/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
    # . epilogue
    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
    5d/pop-to-ebp
    c3/return

# (re)compute the bounds of the next word in the line (separated by whitespace)
# return empty string on reaching end of file
next-raw-word:  # line: (addr stream byte), out: (addr slice)
    # . prologue
    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-whitespace(line)
    # . . push args
    ff          6/subop/push        1/mod/*+disp8   5/rm32/ebp    .           .             .           .           8/disp8         .                 # push *(ebp+8)
    # . . call
    e8/call  skip-chars-matching-whitespace/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
$next-raw-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-<  $next-raw-word:word-exists/disp8
    # . return out
    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-raw-word:end/disp8
$next-raw-word:word-exists:
    # 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
    # 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-raw-word:end:
    # . restore registers
    5f/pop-to-edi
    5e/pop-to-esi
    59/pop-to-ecx
    58/pop-to-eax
    # . epilogue
    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
    5d/pop-to-ebp
    c3/return