# Print the (hex) textual representation of numbers.

== 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

to-hex-char:  # in/EAX : nibble -> out/EAX : byte
    # no error checking; accepts argument in EAX
    # if (EAX <= 9) return EAX + '0'
    3d/compare-EAX-with  0x9/imm32/9
    7f/jump-if-greater  $to-hex-char:else/disp8
    05/add-to-EAX  0x30/imm32/0
    c3/return
$to-hex-char:else:
    # otherwise return EAX + 'a' - 10
    05/add-to-EAX  0x57/imm32/a-10
    c3/return

append-byte-hex:  # f : (address stream), n : int -> <void>
    # . prolog
    55/push-EBP
    89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
    # . save registers
    50/push-EAX
    # AL = convert upper nibble to hex
    8b/copy                         1/mod/*+disp8   5/rm32/EBP    .           .             .           0/r32/EAX   0xc/disp8       .                 # copy *(EBP+12) to EAX
    c1/shift    5/subop/logic-right 3/mod/direct    0/rm32/EAX    .           .             .           .           .               4/imm8            # shift EAX right by 4 bits, while padding zeroes
    25/and-EAX  0xf/imm32
    # . AL = to-hex-char(AL)
    e8/call  to-hex-char/disp32
    # append-byte(f, AL)
    # . . push args
    50/push-EAX
    ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           8/disp8         .                 # push *(EBP+8)
    # . . call
    e8/call  append-byte/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
    # AL = convert lower nibble to hex
    8b/copy                         1/mod/*+disp8   5/rm32/EBP    .           .             .           0/r32/EAX   0xc/disp8       .                 # copy *(EBP+12) to EAX
    25/and-EAX  0xf/imm32
    # . AL = to-hex-char(AL)
    e8/call  to-hex-char/disp32
    # append-byte(f, AL)
    # . . push args
    50/push-EAX
    ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           8/disp8         .                 # push *(EBP+8)
    # . . call
    e8/call  append-byte/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
$append-byte-hex: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-append-byte-hex:
    # - check that append-byte-hex adds the hex textual representation
    # 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
    # append-byte-hex(_test-stream, 0xa)  # exercises digit, non-digit as well as leading zero
    # . . push args
    68/push  0xa/imm32
    68/push  _test-stream/imm32
    # . . call
    e8/call  append-byte-hex/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
    # check-stream-equal(_test-stream, "0a", msg)
    # . . push args
    68/push  "F - test-append-byte-hex"/imm32
    68/push  "0a"/imm32
    68/push  _test-stream/imm32
    # . . call
    e8/call  check-stream-equal/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0xc/imm32         # add to ESP
    # . end
    c3/return

# print the hex representation for the lowest byte of a number
print-byte-buffered:  # f : (address buffered-file), n : int -> <void>
    # . prolog
    55/push-EBP
    89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
    # . save registers
    50/push-EAX
    # AL = convert upper nibble to hex
    8b/copy                         1/mod/*+disp8   5/rm32/EBP    .           .             .           0/r32/EAX   0xc/disp8       .                 # copy *(EBP+12) to EAX
    c1/shift    5/subop/logic-right 3/mod/direct    0/rm32/EAX    .           .             .           .           .               4/imm8            # shift EAX right by 4 bits, while padding zeroes
    25/and-EAX  0xf/imm32
    # . AL = to-hex-char(AL)
    e8/call  to-hex-char/disp32
    # write-byte-buffered(f, AL)
    # . . push args
    50/push-EAX
    ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           8/disp8         .                 # push *(EBP+8)
    # . . call
    e8/call  write-byte-buffered/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
    # AL = convert lower nibble to hex
    8b/copy                         1/mod/*+disp8   5/rm32/EBP    .           .             .           0/r32/EAX   0xc/disp8       .                 # copy *(EBP+12) to EAX
    25/and-EAX  0xf/imm32
    # . AL = to-hex-char(AL)
    e8/call  to-hex-char/disp32
    # write-byte-buffered(f, AL)
    # . . push args
    50/push-EAX
    ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           8/disp8         .                 # push *(EBP+8)
    # . . call
    e8/call  write-byte-buffered/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
$print-byte-buffered: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-print-byte-buffered:
    # - check that print-byte-buffered prints the hex textual representation
    # 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
    # print-byte-buffered(_test-buffered-file, 0xa)  # exercises digit, non-digit as well as leading zero
    # . . push args
    68/push  0xa/imm32
    68/push  _test-buffered-file/imm32
    # . . call
    e8/call  print-byte-buffered/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
    # flush(_test-buffered-file)
    # . . push args
    68/push  _test-buffered-file/imm32
    # . . call
    e8/call  flush/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
    # check-stream-equal(_test-stream, "0a", msg)
    # . . push args
    68/push  "F - test-print-byte-buffered"/imm32
    68/push  "0a"/imm32
    68/push  _test-stream/imm32
    # . . call
    e8/call  check-stream-equal/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0xc/imm32         # add to ESP
    # . end
    c3/return

print-int32:  # f : (address stream), n : int -> <void>
    # pseudocode:
    #  write(f, "0x")
    #  ECX = 28
    #  while true
    #    if (ECX < 0) break
    #    EAX = n >> ECX
    #    EAX = EAX & 0xf
    #    append-byte(f, AL)
    #    ECX -= 4
    #
    # . 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
    # ECX = 28
    b9/copy-to-ECX  0x1c/imm32
$print-int32:print-hex-prefix:
    # write(f, "0x")
    # . . push args
    68/push  "0x"/imm32
    ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           8/disp8         .                 # push *(EBP+8)
    # . . call
    e8/call  write/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
$print-int32:loop:
    # if (ECX < 0) break
    81          7/subop/compare     3/mod/direct    1/rm32/ECX    .           .             .           .           .               0/imm32           # compare ECX
    7c/jump-if-lesser  $print-int32:end/disp8
    # EAX = n >> ECX
    8b/copy                         1/mod/*+disp8   5/rm32/EBP    .           .             .           0/r32/EAX   0xc/disp8       .                 # copy *(EBP+12) to EAX
    d3/>>ECX    5/subop/pad-zeroes  3/mod/direct    0/rm32/EAX    .           .             .           .           .               .                 # shift EAX right by ECX bits, padding zeroes
    # EAX = to-hex-char(AL)
    25/and-EAX  0xf/imm32
    e8/call  to-hex-char/disp32
    # append-byte(f, AL)
    # . . push args
    50/push-EAX
    ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           8/disp8         .                 # push *(EBP+8)
    # . . call
    e8/call  append-byte/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
    # ECX -= 4
    81          5/subop/subtract    3/mod/direct    1/rm32/ECX    .           .             .           .           .               4/imm32           # subtract from ECX
    eb/jump  $print-int32:loop/disp8
$print-int32:end:
    # . restore registers
    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-print-int32:
    # - check that print-int32 prints the hex textual representation
    # 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
    # print-int32(_test-stream, 0x8899aa)
    # . . push args
    68/push  0x8899aa/imm32
    68/push  _test-stream/imm32
    # . . call
    e8/call  print-int32/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
    # check-stream-equal(_test-stream, "0x008899aa", msg)
    # . . push args
    68/push  "F - test-print-int32"/imm32
    68/push  "0x008899aa"/imm32
    68/push  _test-stream/imm32
    # . . call
    e8/call  check-stream-equal/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0xc/imm32         # add to ESP
    # . end
    c3/return

print-int32-buffered:  # f : (address buffered-file), n : int -> <void>
    # pseudocode:
    #  write-buffered(f, "0x")
    #  ECX = 28
    #  while true
    #    if (ECX < 0) break
    #    EAX = n >> ECX
    #    EAX = EAX & 0xf
    #    write-byte-buffered(f, AL)
    #    ECX -= 4
    #
    # . 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
    # ECX = 28
    b9/copy-to-ECX  0x1c/imm32
$print-int32-buffered:print-hex-prefix:
    # write-buffered(f, "0x")
    # . . push args
    68/push  "0x"/imm32
    ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           8/disp8         .                 # push *(EBP+8)
    # . . call
    e8/call  write-buffered/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
$print-int32-buffered:loop:
    # if (ECX < 0) break
    81          7/subop/compare     3/mod/direct    1/rm32/ECX    .           .             .           .           .               0/imm32           # compare ECX
    7c/jump-if-lesser  $print-int32-buffered:end/disp8
    # EAX = n >> ECX
    8b/copy                         1/mod/*+disp8   5/rm32/EBP    .           .             .           0/r32/EAX   0xc/disp8       .                 # copy *(EBP+12) to EAX
    d3/>>ECX    5/subop/pad-zeroes  3/mod/direct    0/rm32/EAX    .           .             .           .           .               .                 # shift EAX right by ECX bits, padding zeroes
    # EAX = to-hex-char(AL)
    25/and-EAX  0xf/imm32
    e8/call  to-hex-char/disp32
    # write-byte-buffered(f, AL)
    # . . push args
    50/push-EAX
    ff          6/subop/push        1/mod/*+disp8   5/rm32/EBP    .           .             .           .           8/disp8         .                 # push *(EBP+8)
    # . . call
    e8/call  write-byte-buffered/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
    # ECX -= 4
    81          5/subop/subtract    3/mod/direct    1/rm32/ECX    .           .             .           .           .               4/imm32           # subtract from ECX
    eb/jump  $print-int32-buffered:loop/disp8
$print-int32-buffered:end:
    # . restore registers
    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-print-int32-buffered:
    # - check that print-int32-buffered prints the hex textual representation
    # 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
    # print-int32-buffered(_test-buffered-file, 0x8899aa)
    # . . push args
    68/push  0x8899aa/imm32
    68/push  _test-buffered-file/imm32
    # . . call
    e8/call  print-int32-buffered/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
    # flush(_test-buffered-file)
    # . . push args
    68/push  _test-buffered-file/imm32
    # . . call
    e8/call  flush/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               4/imm32           # add to ESP
#?     # dump line {{{
#?     # . write-stream(2/stderr, line)
#?     # . . push args
#?     68/push  _test-stream/imm32
#?     68/push  2/imm32/stderr
#?     # . . call
#?     e8/call  write-stream/disp32
#?     # . . discard args
#?     81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
#?     # . write(2/stderr, "$\n")
#?     # . . push args
#?     68/push  "$\n"/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
#?     # }}}
    # check-stream-equal(_test-stream, "0x008899aa", msg)
    # . . push args
    68/push  "F - test-print-int32-buffered"/imm32
    68/push  "0x008899aa"/imm32
    68/push  _test-stream/imm32
    # . . call
    e8/call  check-stream-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