# Read a text file containing whitespace-separated ascii hex bytes from stdin,
# and convert them into a binary file.
#
# To run (from the subx/ directory):
#   $ ./subx translate *.subx apps/hex.subx -o apps/hex
#   $ echo '80 81 82  # comment'  |./subx run apps/hex  |xxd -
# Expected output:
#   00000000: 8081 82
#
# Only hex bytes and comments are permitted. Outside of comments all words
# must be exactly 2 characters long and contain only characters [0-9a-f]. No
# uppercase hex.

== 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

    # for debugging: run a single test
#?     e8/call test-skip-until-newline/disp32
#?     8b/copy                         0/mod/indirect  5/rm32/.disp32            .             .           3/r32/EBX   Num-test-failures/disp32          # copy *Num-test-failures to EBX
#?     eb/jump  $main:end/disp8

# main: run tests if necessary, convert stdin if not
    # . prolog
    89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
    # - if argc > 1 and argv[1] == "test" then return run_tests()
    # . argc > 1
    81          7/subop/compare     1/mod/*+disp8   4/rm32/sib    5/base/EBP  4/index/none  .           .           0/disp8         1/imm32           # compare *EBP
    7e/jump-if-lesser-or-equal  $run-main/disp8
    # . argv[1] == "test"
    # . . push args
    68/push  "test"/imm32
    ff          6/subop/push        1/mod/*+disp8   4/rm32/sib    5/base/EBP  4/index/none  .           .           8/disp8         .                 # push *(EBP+8)
    # . . call
    e8/call  kernel-string-equal/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
    # . check result
    3d/compare-EAX  1/imm32
    75/jump-if-not-equal  $run-main/disp8
    # . run-tests()
#?     e8/call test-hex-below-0/disp32
#?     e8/call test-scan-next-byte/disp32
#?     e8/call test-scan-next-byte-handles-eof/disp32
#?     e8/call test-scan-next-byte-skips-comment/disp32
    e8/call  run-tests/disp32
    8b/copy                         0/mod/indirect  5/rm32/.disp32            .             .           3/r32/EBX   Num-test-failures/disp32          # copy *Num-test-failures to EBX
    eb/jump  $main:end/disp8
$run-main:
    # - otherwise convert stdin
    # var ed/EAX : exit-descriptor
    81          5/subop/subtract    3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # subtract from ESP
    8d/copy-address                 0/mod/indirect  4/rm32/sib    4/base/ESP  4/index/none  .           0/r32/EAX   .               .                 # copy ESP to EAX
    # configure ed to really exit()
    # . ed->target = 0
    c7/copy                         0/mod/direct    0/rm32/EAX    .           .             .           .           .               0/imm32           # copy to *EAX
    # return convert(Stdin, 1/stdout, 2/stderr, ed)
    # . . push args
    50/push-EAX/ed
    68/push  2/imm32/stderr
    68/push  1/imm32/stdout
    68/push  Stdin/imm32
    # . . call
    e8/call  convert/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0x10/imm32        # add to ESP
    # . syscall(exit, 0)
    bb/copy-to-EBX  0/imm32
$main:end:
    b8/copy-to-EAX  1/imm32/exit
    cd/syscall  0x80/imm8

# the main entry point
convert:  # in : (address buffered-file), out : (address buffered-file), err : (address buffered-file), ed : (address exit-descriptor) -> <void>
    # . prolog
    55/push-EBP
    89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
    # . save registers
$convert:end:
    # . restore registers
    # . epilog
    89/copy                         3/mod/direct    4/rm32/ESP    .           .             .           5/r32/EBP   .               .                 # copy EBP to ESP
    5d/pop-to-EBP
    c3/return

# read bytes from 'in' until a sequence of two lowercase hex characters (0-9, a-f)
# skip spaces and newlines
# on '#' skip bytes until newline
# raise an error and abort on all other unexpected bytes
# return the binary value of the two hex characters in EAX
# return 0xffffffff on end of file
convert-next-hex-byte:  # in : (address buffered-file), err : (address buffered-file), ed : (address exit-descriptor) -> byte-or-eof/EAX
    # pseudocode:
    #   EAX = scan-next-byte(in, err, ed)
    #   if (EAX == 0xffffffff) return
    #   ECX = EAX
    #   EAX = scan-next-byte(in, err, ed)
    #   if (EAX == 0xffffffff) error("partial byte found")
    #   ECX = (ECX << 8) | EAX
    #   return
    #
    # . prolog
    55/push-EBP
    89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
    # . save registers
$convert-next-hex-byte:end:
    # . restore registers
    # . epilog
    89/copy                         3/mod/direct    4/rm32/ESP    .           .             .           5/r32/EBP   .               .                 # copy EBP to ESP
    5d/pop-to-EBP
    c3/return

# read whitespace until a hex byte, and return it
# return 0xffffffff if file ends without finding a hex byte
# on '#' skip all bytes until newline
# abort on any other byte
scan-next-byte:  # in : (address buffered-file), err : (address buffered-file), ed : (address exit-descriptor) -> byte-or-eof/EAX
    # pseudocode:
    #   repeatedly
    #     EAX = read-byte(in)
    #     if EAX == 0xffffffff return EAX
    #     if is-hex-lowercase-byte?(EAX) return EAX
    #     if EAX == 0x20 continue
    #     if EAX == '#' skip-until-newline(in)
    #     else error-byte(ed, err, "unexpected byte: " EAX)
    #
    # . prolog
    55/push-EBP
    89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
    # . save registers
$scan-next-byte:loop:
    # EAX = read-byte(in)
    # . . push args
    ff          6/subop/push        1/mod/*+disp8   4/rm32/sib    5/base/EBP  4/index/none  .           .           8/disp8         .                 # push *(EBP+8)
    # . . call
    e8/call  read-byte/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
    # if (EAX == 0xffffffff) return EAX
    3d/compare-with-EAX  0xffffffff/imm32
    74/jump-if-equal  $scan-next-byte:end/disp8
    # if is-hex-lowercase-byte?(EAX) return EAX
    # . save EAX for now
    50/push-EAX
    # . is-hex-lowercase-byte?(EAX)
    # . . push args
    50/push-EAX
    # . . call
    e8/call  is-hex-lowercase-byte?/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
    # . compare with 'false'
    3d/compare-with-EAX  0/imm32
    # . restore EAX (does not affect flags)
    58/pop-to-EAX
    # . check whether to return
    75/jump-if-not-equal  $scan-next-byte:end/disp8
$scan-next-byte:check1:
    # if EAX == ' ' continue
    81          7/subop/compare     3/mod/direct    0/rm32/EAX    .           .             .           .           .               0x20/imm32        # compare EAX
    74/jump-if-equal  $scan-next-byte:loop/disp8
    # if EAX == '\t' continue
    81          7/subop/compare     3/mod/direct    0/rm32/EAX    .           .             .           .           .               0x9/imm32         # compare EAX
    74/jump-if-equal  $scan-next-byte:loop/disp8
    # if EAX == '\n' continue
    81          7/subop/compare     3/mod/direct    0/rm32/EAX    .           .             .           .           .               0xa/imm32         # compare EAX
    74/jump-if-equal  $scan-next-byte:loop/disp8
$scan-next-byte:check2:
    # if EAX == '#' skip-until-newline(in)
    3d/compare-with-EAX  0x23/imm32
    75/jump-if-not-equal  $scan-next-byte:check3/disp8
    # . skip-until-newline(in)
    # . . push args
    ff          6/subop/push        1/mod/*+disp8   4/rm32/sib    5/base/EBP  4/index/none  .           .           8/disp8         .                 # push *(EBP+8)
    # . . call
    e8/call  skip-until-newline/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
    eb/jump  $scan-next-byte:loop/disp8
$scan-next-byte:check3:
    # otherwise error-byte(ed, err, msg, EAX)
    # . . push args
    50/push-EAX
    68/push  "scan-next-byte: invalid byte"/imm32
    ff          6/subop/push        1/mod/*+disp8   4/rm32/sib    5/base/EBP  4/index/none  .           .           0xc/disp8       .                 # push *(EBP+12)
    ff          6/subop/push        1/mod/*+disp8   4/rm32/sib    5/base/EBP  4/index/none  .           .           0x10/disp8      .                 # push *(EBP+16)
    # . . call
    e8/call  error-byte/disp32  # never returns
$scan-next-byte:end:
    # . restore registers
    # . epilog
    89/copy                         3/mod/direct    4/rm32/ESP    .           .             .           5/r32/EBP   .               .                 # copy EBP to ESP
    5d/pop-to-EBP
    c3/return

test-scan-next-byte:
    # - check that the first byte of the input is returned
    # This test uses exit-descriptors. Use EBP for setting up local variables.
    55/push-EBP
    89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
    # clear all streams
    # . 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-error-stream)
    # . . push args
    68/push  _test-error-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
    # initialize '_test-stream' to "abc"
    # . write(_test-stream, "abc")
    # . . push args
    68/push  "abc"/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
    # initialize exit-descriptor 'ed' for the call to 'scan-next-byte' below
    # . var ed/ECX : exit-descriptor
    81          5/subop/subtract    3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # subtract from ESP
    8d/copy-address                 0/mod/indirect  4/rm32/sib    4/base/ESP  4/index/none  .           1/r32/ECX   .               .                 # copy ESP to ECX
    # . tailor-exit-descriptor(ed, 12)
    # . . push args
    68/push  0xc/imm32/nbytes-of-args-for-scan-next-byte
    51/push-ECX/ed
    # . . call
    e8/call  tailor-exit-descriptor/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
    # EAX = scan-next-byte(_test-buffered-file, _test-error-stream, ed)
    # . . push args
    51/push-ECX/ed
    68/push  _test-error-stream/imm32
    68/push  _test-buffered-file/imm32
    # . . call
    e8/call  scan-next-byte/disp32
    # registers except ESP may be clobbered at this point
    # pop args to scan-next-bytes
    # . . discard first 2 args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
    # . . restore ed
    59/pop-to-ECX
    # check that scan-next-byte didn't abort
    # . check-ints-equal(ed->value, 0, msg)
    # . . push args
    68/push  "F - test-scan-next-byte: unexpected abort"/imm32
    68/push  0/imm32
    # . . push ed->value
    ff          6/subop/push        1/mod/*+disp8   1/rm32/ECX    .           .             .           .           4/disp8         .                 # push *(ECX+4)
    # . . call
    e8/call  check-ints-equal/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0xc/imm32         # add to ESP
    # return if abort
    81          7/subop/compare     1/mod/*+disp8   1/rm32/ECX    .           .             .           .           4/disp8         0/imm32           # compare *(ECX+4)
    75/jump-if-not-equal  $test-scan-next-byte:end/disp8
    # check-ints-equal(EAX, 0x61/a, msg)
    # . . push args
    68/push  "F - test-scan-next-byte"/imm32
    68/push  0x61/imm32/a
    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
$test-scan-next-byte:end:
    # . epilog
    # don't restore ESP from EBP; manually reclaim locals
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
    5d/pop-to-EBP
    c3/return

test-scan-next-byte-skips-whitespace:
    # - check that the first byte after whitespace is returned
    # This test uses exit-descriptors. Use EBP for setting up local variables.
    55/push-EBP
    89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
    # clear all streams
    # . 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-error-stream)
    # . . push args
    68/push  _test-error-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
    # initialize '_test-stream' to input with leading whitespace
    # . write(_test-stream, text)
    # . . push args
    68/push  "  abc"/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
    # initialize exit-descriptor 'ed' for the call to 'scan-next-byte' below
    # . var ed/ECX : exit-descriptor
    81          5/subop/subtract    3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # subtract from ESP
    8d/copy-address                 0/mod/indirect  4/rm32/sib    4/base/ESP  4/index/none  .           1/r32/ECX   .               .                 # copy ESP to ECX
    # . tailor-exit-descriptor(ed, 12)
    # . . push args
    68/push  0xc/imm32/nbytes-of-args-for-scan-next-byte
    51/push-ECX/ed
    # . . call
    e8/call  tailor-exit-descriptor/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
    # EAX = scan-next-byte(_test-buffered-file, _test-error-stream, ed)
    # . . push args
    51/push-ECX/ed
    68/push  _test-error-stream/imm32
    68/push  _test-buffered-file/imm32
    # . . call
    e8/call  scan-next-byte/disp32
    # registers except ESP may be clobbered at this point
    # pop args to scan-next-bytes
    # . . discard first 2 args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
    # . . restore ed
    59/pop-to-ECX
    # check that scan-next-byte didn't abort
    # . check-ints-equal(ed->value, 0, msg)
    # . . push args
    68/push  "F - test-scan-next-byte-skips-whitespace: unexpected abort"/imm32
    68/push  0/imm32
    # . . push ed->value
    ff          6/subop/push        1/mod/*+disp8   1/rm32/ECX    .           .             .           .           4/disp8         .                 # push *(ECX+4)
    # . . call
    e8/call  check-ints-equal/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0xc/imm32         # add to ESP
    # return if abort
    81          7/subop/compare     1/mod/*+disp8   1/rm32/ECX    .           .             .           .           4/disp8         0/imm32           # compare *(ECX+4)
    75/jump-if-not-equal  $test-scan-next-byte-skips-whitespace:end/disp8
    # check-ints-equal(EAX, 0x61/a, msg)
    # . . push args
    68/push  "F - test-scan-next-byte-skips-whitespace"/imm32
    68/push  0x61/imm32/a
    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
$test-scan-next-byte-skips-whitespace:end:
    # . epilog
    # don't restore ESP from EBP; manually reclaim locals
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
    5d/pop-to-EBP
    c3/return

test-scan-next-byte-skips-comment:
    # - check that the first byte after a comment (and newline) is returned
    # This test uses exit-descriptors. Use EBP for setting up local variables.
    55/push-EBP
    89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
    # clear all streams
    # . 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-error-stream)
    # . . push args
    68/push  _test-error-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
    # initialize '_test-stream' to input with leading comment
    # . write(_test-stream, comment)
    # . . push args
    68/push  "#x"/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, Newline)
    # . . 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, real text)
    # . . 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
    # initialize exit-descriptor 'ed' for the call to 'scan-next-byte' below
    # . var ed/ECX : exit-descriptor
    81          5/subop/subtract    3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # subtract from ESP
    8d/copy-address                 0/mod/indirect  4/rm32/sib    4/base/ESP  4/index/none  .           1/r32/ECX   .               .                 # copy ESP to ECX
    # . tailor-exit-descriptor(ed, 12)
    # . . push args
    68/push  0xc/imm32/nbytes-of-args-for-scan-next-byte
    51/push-ECX/ed
    # . . call
    e8/call  tailor-exit-descriptor/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
    # EAX = scan-next-byte(_test-buffered-file, _test-error-stream, ed)
    # . . push args
    51/push-ECX/ed
    68/push  _test-error-stream/imm32
    68/push  _test-buffered-file/imm32
    # . . call
    e8/call  scan-next-byte/disp32
    # registers except ESP may be clobbered at this point
    # pop args to scan-next-bytes
    # . . discard first 2 args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
    # . . restore ed
    59/pop-to-ECX
    # check that scan-next-byte didn't abort
    # . check-ints-equal(ed->value, 0, msg)
    # . . push args
    68/push  "F - test-scan-next-byte-skips-comment: unexpected abort"/imm32
    68/push  0/imm32
    # . . push ed->value
    ff          6/subop/push        1/mod/*+disp8   1/rm32/ECX    .           .             .           .           4/disp8         .                 # push *(ECX+4)
    # . . call
    e8/call  check-ints-equal/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0xc/imm32         # add to ESP
    # return if abort
    81          7/subop/compare     1/mod/*+disp8   1/rm32/ECX    .           .             .           .           4/disp8         0/imm32           # compare *(ECX+4)
    75/jump-if-not-equal  $test-scan-next-byte-skips-comment:end/disp8
    # check-ints-equal(EAX, 0x61/a, msg)
    # . . push args
    68/push  "F - test-scan-next-byte-skips-comment"/imm32
    68/push  0x61/imm32/a
    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
$test-scan-next-byte-skips-comment:end:
    # . epilog
    # don't restore ESP from EBP; manually reclaim locals
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
    5d/pop-to-EBP
    c3/return

test-scan-next-byte-skips-comment-and-whitespace:
    # - check that the first byte after a comment and any further whitespace is returned
    # This test uses exit-descriptors. Use EBP for setting up local variables.
    55/push-EBP
    89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
    # clear all streams
    # . 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-error-stream)
    # . . push args
    68/push  _test-error-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
    # initialize '_test-stream' to input with leading comment and more whitespace after newline
    # . write(_test-stream, comment)
    # . . push args
    68/push  "#x"/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, Newline)
    # . . 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, real text)
    # . . 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
    # initialize exit-descriptor 'ed' for the call to 'scan-next-byte' below
    # . var ed/ECX : exit-descriptor
    81          5/subop/subtract    3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # subtract from ESP
    8d/copy-address                 0/mod/indirect  4/rm32/sib    4/base/ESP  4/index/none  .           1/r32/ECX   .               .                 # copy ESP to ECX
    # . tailor-exit-descriptor(ed, 12)
    # . . push args
    68/push  0xc/imm32/nbytes-of-args-for-scan-next-byte
    51/push-ECX/ed
    # . . call
    e8/call  tailor-exit-descriptor/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
    # EAX = scan-next-byte(_test-buffered-file, _test-error-stream, ed)
    # . . push args
    51/push-ECX/ed
    68/push  _test-error-stream/imm32
    68/push  _test-buffered-file/imm32
    # . . call
    e8/call  scan-next-byte/disp32
    # registers except ESP may be clobbered at this point
    # pop args to scan-next-bytes
    # . . discard first 2 args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
    # . . restore ed
    59/pop-to-ECX
    # check that scan-next-byte didn't abort
    # . check-ints-equal(ed->value, 0, msg)
    # . . push args
    68/push  "F - test-scan-next-byte-skips-comment-and-whitespace: unexpected abort"/imm32
    68/push  0/imm32
    # . . push ed->value
    ff          6/subop/push        1/mod/*+disp8   1/rm32/ECX    .           .             .           .           4/disp8         .                 # push *(ECX+4)
    # . . call
    e8/call  check-ints-equal/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0xc/imm32         # add to ESP
    # return if abort
    81          7/subop/compare     1/mod/*+disp8   1/rm32/ECX    .           .             .           .           4/disp8         0/imm32           # compare *(ECX+4)
    75/jump-if-not-equal  $test-scan-next-byte-skips-comment-and-whitespace:end/disp8
    # check-ints-equal(EAX, 0x61/a, msg)
    # . . push args
    68/push  "F - test-scan-next-byte-skips-comment-and-whitespace"/imm32
    68/push  0x61/imm32/a
    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
$test-scan-next-byte-skips-comment-and-whitespace:end:
    # . epilog
    # don't restore ESP from EBP; manually reclaim locals
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
    5d/pop-to-EBP
    c3/return

test-scan-next-byte-skips-whitespace-and-comment:
    # - check that the first byte after any whitespace and comments is returned
    # This test uses exit-descriptors. Use EBP for setting up local variables.
    55/push-EBP
    89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
    # clear all streams
    # . 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-error-stream)
    # . . push args
    68/push  _test-error-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
    # initialize '_test-stream' to input with leading whitespace and comment
    # . write(_test-stream, comment)
    # . . push args
    68/push  " #x"/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, Newline)
    # . . 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, real text)
    # . . 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
    # initialize exit-descriptor 'ed' for the call to 'scan-next-byte' below
    # . var ed/ECX : exit-descriptor
    81          5/subop/subtract    3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # subtract from ESP
    8d/copy-address                 0/mod/indirect  4/rm32/sib    4/base/ESP  4/index/none  .           1/r32/ECX   .               .                 # copy ESP to ECX
    # . tailor-exit-descriptor(ed, 12)
    # . . push args
    68/push  0xc/imm32/nbytes-of-args-for-scan-next-byte
    51/push-ECX/ed
    # . . call
    e8/call  tailor-exit-descriptor/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
    # EAX = scan-next-byte(_test-buffered-file, _test-error-stream, ed)
    # . . push args
    51/push-ECX/ed
    68/push  _test-error-stream/imm32
    68/push  _test-buffered-file/imm32
    # . . call
    e8/call  scan-next-byte/disp32
    # registers except ESP may be clobbered at this point
    # pop args to scan-next-bytes
    # . . discard first 2 args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
    # . . restore ed
    59/pop-to-ECX
    # check that scan-next-byte didn't abort
    # . check-ints-equal(ed->value, 0, msg)
    # . . push args
    68/push  "F - test-scan-next-byte-skips-whitespace-and-comment: unexpected abort"/imm32
    68/push  0/imm32
    # . . push ed->value
    ff          6/subop/push        1/mod/*+disp8   1/rm32/ECX    .           .             .           .           4/disp8         .                 # push *(ECX+4)
    # . . call
    e8/call  check-ints-equal/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0xc/imm32         # add to ESP
    # return if abort
    81          7/subop/compare     1/mod/*+disp8   1/rm32/ECX    .           .             .           .           4/disp8         0/imm32           # compare *(ECX+4)
    75/jump-if-not-equal  $test-scan-next-byte-skips-whitespace-and-comment:end/disp8
    # check-ints-equal(EAX, 0x61/a, msg)
    # . . push args
    68/push  "F - test-scan-next-byte-skips-whitespace-and-comment"/imm32
    68/push  0x61/imm32/a
    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
$test-scan-next-byte-skips-whitespace-and-comment:end:
    # . epilog
    # don't restore ESP from EBP; manually reclaim locals
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
    5d/pop-to-EBP
    c3/return

test-scan-next-byte-reads-final-byte:
    # - check that the final byte in input is returned
    # This test uses exit-descriptors. Use EBP for setting up local variables.
    55/push-EBP
    89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
    # clear all streams
    # . 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-error-stream)
    # . . push args
    68/push  _test-error-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
    # initialize '_test-stream' to input with single character
    # . write(_test-stream, character)
    # . . 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
    # initialize exit-descriptor 'ed' for the call to 'scan-next-byte' below
    # . var ed/ECX : exit-descriptor
    81          5/subop/subtract    3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # subtract from ESP
    8d/copy-address                 0/mod/indirect  4/rm32/sib    4/base/ESP  4/index/none  .           1/r32/ECX   .               .                 # copy ESP to ECX
    # . tailor-exit-descriptor(ed, 12)
    # . . push args
    68/push  0xc/imm32/nbytes-of-args-for-scan-next-byte
    51/push-ECX/ed
    # . . call
    e8/call  tailor-exit-descriptor/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
    # EAX = scan-next-byte(_test-buffered-file, _test-error-stream, ed)
    # . . push args
    51/push-ECX/ed
    68/push  _test-error-stream/imm32
    68/push  _test-buffered-file/imm32
    # . . call
    e8/call  scan-next-byte/disp32
    # registers except ESP may be clobbered at this point
    # pop args to scan-next-bytes
    # . . discard first 2 args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
    # . . restore ed
    59/pop-to-ECX
    # check that scan-next-byte didn't abort
    # . check-ints-equal(ed->value, 0, msg)
    # . . push args
    68/push  "F - test-scan-next-byte-reads-final-byte: unexpected abort"/imm32
    68/push  0/imm32
    # . . push ed->value
    ff          6/subop/push        1/mod/*+disp8   1/rm32/ECX    .           .             .           .           4/disp8         .                 # push *(ECX+4)
    # . . call
    e8/call  check-ints-equal/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0xc/imm32         # add to ESP
    # return if abort
    81          7/subop/compare     1/mod/*+disp8   1/rm32/ECX    .           .             .           .           4/disp8         0/imm32           # compare *(ECX+4)
    75/jump-if-not-equal  $test-scan-next-byte-reads-final-byte:end/disp8
    # check-ints-equal(EAX, 0x61/a, msg)
    # . . push args
    68/push  "F - test-scan-next-byte-reads-final-byte"/imm32
    68/push  0x61/imm32/a
    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
$test-scan-next-byte-reads-final-byte:end:
    # . epilog
    # don't restore ESP from EBP; manually reclaim locals
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
    5d/pop-to-EBP
    c3/return

test-scan-next-byte-handles-eof:
    # - check that the right sentinel value is returned when there's no data remaining to be read
    # This test uses exit-descriptors. Use EBP for setting up local variables.
    55/push-EBP
    89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
    # clear all streams
    # . 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-error-stream)
    # . . push args
    68/push  _test-error-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
    # leave '_test-stream' empty
    # initialize exit-descriptor 'ed' for the call to 'scan-next-byte' below
    # . var ed/ECX : exit-descriptor
    81          5/subop/subtract    3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # subtract from ESP
    8d/copy-address                 0/mod/indirect  4/rm32/sib    4/base/ESP  4/index/none  .           1/r32/ECX   .               .                 # copy ESP to ECX
    # . tailor-exit-descriptor(ed, 12)
    # . . push args
    68/push  0xc/imm32/nbytes-of-args-for-scan-next-byte
    51/push-ECX/ed
    # . . call
    e8/call  tailor-exit-descriptor/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
    # EAX = scan-next-byte(_test-buffered-file, _test-error-stream, ed)
    # . . push args
    51/push-ECX/ed
    68/push  _test-error-stream/imm32
    68/push  _test-buffered-file/imm32
    # . . call
    e8/call  scan-next-byte/disp32
    # registers except ESP may be clobbered at this point
    # pop args to scan-next-bytes
    # . . discard first 2 args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
    # . . restore ed
    59/pop-to-ECX
    # check that scan-next-byte didn't abort
    # . check-ints-equal(ed->value, 0, msg)
    # . . push args
    68/push  "F - test-scan-next-byte-handles-eof: unexpected abort"/imm32
    68/push  0/imm32
    # . . push ed->value
    ff          6/subop/push        1/mod/*+disp8   1/rm32/ECX    .           .             .           .           4/disp8         .                 # push *(ECX+4)
    # . . call
    e8/call  check-ints-equal/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0xc/imm32         # add to ESP
    # return if abort
    81          7/subop/compare     1/mod/*+disp8   1/rm32/ECX    .           .             .           .           4/disp8         0/imm32           # compare *(ECX+4)
    75/jump-if-not-equal  $test-scan-next-byte-handles-eof:end/disp8
    # check-ints-equal(EAX, 0xffffffff/eof, msg)
    # . . push args
    68/push  "F - test-scan-next-byte-handles-eof"/imm32
    68/push  0xffffffff/imm32/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
$test-scan-next-byte-handles-eof:end:
    # . epilog
    # don't restore ESP from EBP; manually reclaim locals
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
    5d/pop-to-EBP
    c3/return

is-hex-lowercase-byte?:  # c : byte -> bool/EAX
    # . prolog
    55/push-EBP
    89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
    # . save registers
    51/push-ECX
    # ECX = c
    8b/copy                         1/mod/*+disp8   4/rm32/sib    5/base/EBP  4/index/none  .           1/r32/ECX   8/disp8         .                 # copy *(EBP+8) to ECX
    # return false if c < '0'
    b8/copy-to-EAX  0/imm32/false
    81          7/subop/compare     3/mod/direct    1/rm32/ECX    .           .             .           .           .               0x30/imm32        # compare ECX
    7c/jump-if-lesser  $is-hex-lowercase-byte?:end/disp8
    # return false if c > 'f'
    81          7/subop/compare     3/mod/direct    1/rm32/ECX    .           .             .           .           .               0x66/imm32        # compare ECX
    7f/jump-if-greater  $is-hex-lowercase-byte?:end/disp8
    # return true if c <= '9'
    b8/copy-to-EAX  1/imm32/true
    81          7/subop/compare     3/mod/direct    1/rm32/ECX    .           .             .           .           .               0x39/imm32        # compare ECX
    7e/jump-if-lesser-or-equal  $is-hex-lowercase-byte?:end/disp8
    # return true if c >= 'a'
    81          7/subop/compare     3/mod/direct    1/rm32/ECX    .           .             .           .           .               0x61/imm32        # compare ECX
    7d/jump-if-greater-or-equal  $is-hex-lowercase-byte?:end/disp8
    # otherwise return false
    b8/copy-to-EAX  0/imm32/false
$is-hex-lowercase-byte?:end:
    # . restore registers
    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

test-hex-below-0:
    # is-hex-lowercase-byte?(0x2f)
    # . . push args
    68/push  0x2f/imm32
    # . . call
    e8/call  is-hex-lowercase-byte?/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
    # check-ints-equal(EAX, 0, msg)
    # . . push args
    68/push  "F - test-hex-below-0"/imm32
    68/push  0/imm32/false
    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
    c3/return

test-hex-0-to-9:
    # is-hex-lowercase-byte?(0x30)
    # . . push args
    68/push  0x30/imm32
    # . . call
    e8/call  is-hex-lowercase-byte?/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
    # check-ints-equal(EAX, 1, msg)
    # . . push args
    68/push  "F - test-hex-at-0"/imm32
    68/push  1/imm32/true
    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
    # is-hex-lowercase-byte?(0x39)
    # . . push args
    68/push  0x39/imm32
    # . . call
    e8/call  is-hex-lowercase-byte?/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
    # check-ints-equal(EAX, 1, msg)
    # . . push args
    68/push  "F - test-hex-at-9"/imm32
    68/push  1/imm32/true
    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
    c3/return

test-hex-above-9-to-a:
    # is-hex-lowercase-byte?(0x3a)
    # . . push args
    68/push  0x3a/imm32
    # . . call
    e8/call  is-hex-lowercase-byte?/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
    # check-ints-equal(EAX, 0, msg)
    # . . push args
    68/push  "F - test-hex-above-9-to-a"/imm32
    68/push  0/imm32/false
    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
    c3/return

test-hex-a-to-f:
    # is-hex-lowercase-byte?(0x61)
    # . . push args
    68/push  0x61/imm32
    # . . call
    e8/call  is-hex-lowercase-byte?/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
    # check-ints-equal(EAX, 1, msg)
    # . . push args
    68/push  "F - test-hex-at-a"/imm32
    68/push  1/imm32/true
    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
    # is-hex-lowercase-byte?(0x66)
    # . . push args
    68/push  0x66/imm32
    # . . call
    e8/call  is-hex-lowercase-byte?/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
    # check-ints-equal(EAX, 1, msg)
    # . . push args
    68/push  "F - test-hex-at-f"/imm32
    68/push  1/imm32/true
    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
    c3/return

test-hex-above-f:
    # is-hex-lowercase-byte?(0x67)
    # . . push args
    68/push  0x67/imm32
    # . . call
    e8/call  is-hex-lowercase-byte?/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
    # check-ints-equal(EAX, 0, msg)
    # . . push args
    68/push  "F - test-hex-above-f"/imm32
    68/push  0/imm32/false
    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
    c3/return

skip-until-newline:  # in : (address buffered-file) -> <void>
    # pseudocode:
    #   push EAX
    #   repeatedly:
    #     EAX = read-byte(in)
    #     if EAX == 0xffffffff break
    #     if EAX == 0x0a break
    #   pop EAX
    # . prolog
    55/push-EBP
    89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
    # . save registers
    50/push-EAX
$skip-until-newline:loop:
    # . EAX = read-byte(in)
    # . . push args
    ff          6/subop/push        1/mod/*+disp8   4/rm32/sib    5/base/EBP  4/index/none  .           .           8/disp8         .                 # push *(EBP+8)
    # . . call
    e8/call  read-byte/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
    # . if EAX == 0xffffffff break
    81          7/subop/compare     3/mod/direct    0/rm32/EAX    .           .             .           .           .               0xffffffff/imm32  # compare EAX
    74/jump-if-equal  $skip-until-newline:end/disp8
$aa:
    # . if EAX != 0xa/newline loop
    81          7/subop/compare     3/mod/direct    0/rm32/EAX    .           .             .           .           .               0xa/imm32         # compare EAX
    75/jump-if-not-equal  $skip-until-newline:loop/disp8
$skip-until-newline:end:
    # . restore registers
    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-skip-until-newline:
    # - check that the read pointer points after the 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
    # initialize '_test-stream' to "abc\nde"
    # . write(_test-stream, "abc")
    # . . push args
    68/push  "abc"/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, Newline)
    # . . 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, "de")
    # . . push args
    68/push  "de"/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
    # skip-until-newline(_test-buffered-file)
    # . . push args
    68/push  _test-buffered-file/imm32
    # . . call
    e8/call  skip-until-newline/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
    # check-ints-equal(_test-buffered-file->read, 4, msg)
    # . . push args
    68/push  "F - test-skip-until-newline"/imm32
    68/push  4/imm32
    b8/copy-to-EAX  _test-buffered-file/imm32
    ff          6/subop/push        1/mod/*+disp8   0/rm32/EAX    .           .             .           .           8/disp8         .                 # push *(EAX+8)
    # . . 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

== data

_test-output-stream:
    # current write index
    00 00 00 00
    # current read index
    00 00 00 00
    # length (= 8)
    08 00 00 00
    # data
    00 00 00 00 00 00 00 00  # 8 bytes

_test-error-stream:
    # current write index
    00 00 00 00
    # current read index
    00 00 00 00
    # length (= 8)
    08 00 00 00
    # data
    00 00 00 00 00 00 00 00  # 8 bytes

# . . vim:nowrap:textwidth=0