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<a href='https://github.com/akkartik/mu/blob/master/display.mu'>https://github.com/akkartik/mu/blob/master/display.mu</a>
<pre id='vimCodeElement'>
<span id="L1" class="LineNr"> 1 </span><span class="Comment"># example program: managing the display</span>
<span id="L2" class="LineNr"> 2 </span>
<span id="L3" class="LineNr"> 3 </span><span class="muRecipe">def</span> <a href='display.mu.html#L3'>main</a> [
<span id="L4" class="LineNr"> 4 </span>  open-console
<span id="L5" class="LineNr"> 5 </span>  clear-display
<span id="L6" class="LineNr"> 6 </span>  print-character-to-display<span class="Constant"> 97</span>, <span class="Constant">1/red</span>, <span class="Constant">2/green</span>
<span id="L7" class="LineNr"> 7 </span>  1:num/<span class="Special">raw</span>, 2:num/<span class="Special">raw</span> <span class="Special">&lt;-</span> cursor-position-on-display
<span id="L8" class="LineNr"> 8 </span>  wait-for-some-interaction
<span id="L9" class="LineNr"> 9 </span>  clear-line-on-display
<span id="L10" class="LineNr">10 </span>  move-cursor-on-display<span class="Constant"> 0</span>,<span class="Constant"> 4</span>
<span id="L11" class="LineNr">11 </span>  print-character-to-display<span class="Constant"> 98</span>
<span id="L12" class="LineNr">12 </span>  wait-for-some-interaction
<span id="L13" class="LineNr">13 </span>  move-cursor-on-display<span class="Constant"> 0</span>,<span class="Constant"> 0</span>
<span id="L14" class="LineNr">14 </span>  clear-line-on-display
<span id="L15" class="LineNr">15 </span>  wait-for-some-interaction
<span id="L16" class="LineNr">16 </span>  move-cursor-down-on-display
<span id="L17" class="LineNr">17 </span>  wait-for-some-interaction
<span id="L18" class="LineNr">18 </span>  move-cursor-right-on-display
<span id="L19" class="LineNr">19 </span>  wait-for-some-interaction
<span id="L20" class="LineNr">20 </span>  move-cursor-left-on-display
<span id="L21" class="LineNr">21 </span>  wait-for-some-interaction
<span id="L22" class="LineNr">22 </span>  move-cursor-up-on-display
<span id="L23" class="LineNr">23 </span>  wait-for-some-interaction
<span id="L24" class="LineNr">24 </span>  close-console
<span id="L25" class="LineNr">25 </span>]
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Kartik Agaram <vc@akkartik.com> 2018-11-30 10:54:42 -0800 committer Kartik Agaram <vc@akkartik.com> 2018-11-30 10:54:42 -0800 4801' href='/akkartik/mu/commit/subx/056write.subx?h=hlt&id=6030d7e2e56d445ca67c6a0e8c9cf33e46bc673c'>6030d7e2 ^
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# write: write to in-memory streams
#
# We need to do this in machine code because streams need to be opaque types,
# and we don't yet support opaque types in Mu.

== 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

write:  # f: (addr stream byte), s: (addr array byte)
    # . prologue
    55/push-ebp
    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
    # if (s == 0) return
    81          7/subop/compare     1/mod/*+disp8   5/rm32/ebp    .           .             .           .           0xc/disp8       0/imm32           # compare *(ebp+12)
    74/jump-if-=  $write:end/disp8
    # . save registers
    50/push-eax
    51/push-ecx
    52/push-edx
    53/push-ebx
    # ecx = f
    8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .                         1/r32/ecx   8/disp8         .                 # copy *(ebp+8) to ecx
    # edx = f->write
    8b/copy                         0/mod/indirect  1/rm32/ecx    .           .             .           2/r32/edx   .               .                 # copy *ecx to edx
    # ebx = f->size
    8b/copy                         1/mod/*+disp8   1/rm32/ecx    .           .             .           3/r32/ebx   8/disp8         .                 # copy *(ecx+8) to ebx
    # eax = _append-3(&f->data[f->write], &f->data[f->size], s)
    # . . push s
    ff          6/subop/push        1/mod/*+disp8   5/rm32/ebp    .           .             .           .           0xc/disp8       .                 # push *(ebp+12)
    # . . push &f->data[f->size]
    8d/copy-address                 1/mod/*+disp8   4/rm32/sib    1/base/ecx  3/index/ebx   .           3/r32/ebx   0xc/disp8       .                 # copy ecx+ebx+12 to ebx
    53/push-ebx
    # . . push &f->data[f->write]
    8d/copy-address                 1/mod/*+disp8   4/rm32/sib    1/base/ecx  2/index/edx   .           3/r32/ebx   0xc/disp8       .                 # copy ecx+edx+12 to ebx
    53/push-ebx
    # . . call
    e8/call  _append-3/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
    # f->write += eax
    01/add                          0/mod/indirect  1/rm32/ecx    .           .             .           0/r32/eax   .               .                 # add eax to *ecx
    # . restore registers
    5b/pop-to-ebx
    5a/pop-to-edx
    59/pop-to-ecx
    58/pop-to-eax
$write:end:
    # . epilogue
    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
    5d/pop-to-ebp
    c3/return

test-write-single:
    # 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
    # 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
    # check-ints-equal(*_test-stream->data, 41/A 62/b 00 00, msg)
    # . . push args
    68/push  "F - test-write-single"/imm32
    68/push  0x006241/imm32/Ab
    # . . push *_test-stream->data
    b8/copy-to-eax  _test-stream/imm32
    ff          6/subop/push        1/mod/*+disp8   0/rm32/eax    .           .             .           .           0xc/disp8       .                 # push *(eax+12)
    # . . call
    e8/call  check-ints-equal/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
    # end
    c3/return

test-write-appends:
    # 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
    # write(_test-stream, "C")
    # . . push args
    68/push  "C"/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, "D")
    # . . push args
    68/push  "D"/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
    # check-ints-equal(*_test-stream->data, 43/C 44/D 00 00, msg)
    # . . push args
    68/push  "F - test-write-appends"/imm32
    68/push  0x00004443/imm32/C-D
    # . . push *_test-stream->data
    b8/copy-to-eax  _test-stream/imm32
    ff          6/subop/push        1/mod/*+disp8   0/rm32/eax    .           .             .           .           0xc/disp8       .                 # push *(eax+12)
    # . . call
    e8/call  check-ints-equal/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
    # end
    c3/return

== data

_test-stream:  # (stream byte)
    # current write index
    0/imm32
    # current read index
    0/imm32
    # size
    0x10/imm32
    # data (2 lines x 8 bytes/line)
    00 00 00 00 00 00 00 00
    00 00 00 00 00 00 00 00

== code

try-write:  # f: (addr stream byte), s: (addr array byte) -> overflow?/eax: boolean
    # . prologue
    55/push-ebp
    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
    # if (s == 0) return
    81          7/subop/compare     1/mod/*+disp8   5/rm32/ebp    .           .             .           .           0xc/disp8       0/imm32           # compare *(ebp+12)
    74/jump-if-=  $try-write:end/disp8
    # . save registers
    51/push-ecx
    # if (f->size - f->write < s->size) return
    # . eax = f->size - f->write - s->size
    8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .                         1/r32/ecx   8/disp8         .                 # copy *(ebp+8) to ecx
    8b/copy                         1/mod/*+disp8   1/rm32/ecx    .           .             .           0/r32/eax   8/disp8         .                 # copy *(ecx+8) to eax
    2b/subtract                     0/mod/indirect  1/rm32/ecx    .           .             .           0/r32/eax   .               .                 # subtract *ecx from eax
    8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .                         1/r32/ecx   0xc/disp8       .                 # copy *(ebp+12) to ecx
    2b/subtract                     0/mod/indirect  1/rm32/ecx    .           .             .           0/r32/eax   .               .                 # subtract *ecx from eax
    # . if (eax < 0) return
    3d/compare-eax-and  0/imm32
    7c/jump-if-<  $try-write:end/disp8
    # write(f, s)
    # . . push args
    ff          6/subop/push        1/mod/*+disp8   5/rm32/ebp    .           .             .           .           0xc/disp8       .                 # push *(ebp+12)
    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
    # . restore registers
    59/pop-to-ecx
    # return 0
    b8/copy-to-eax  0/imm32
$try-write:end:
    # . epilogue
    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
    5d/pop-to-ebp
    c3/return

# probably a bad idea
space-remaining-in-stream:  # f: (addr stream byte) -> n/eax: int
    # . prologue
    55/push-ebp
    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
    # . save registers
    51/push-ecx
    # return f->size - f->write
    8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .                         1/r32/ecx   8/disp8         .                 # copy *(ebp+8) to ecx
    8b/copy                         1/mod/*+disp8   1/rm32/ecx    .           .             .           0/r32/eax   8/disp8         .                 # copy *(ecx+8) to eax
    2b/subtract                     0/mod/indirect  1/rm32/ecx    .           .             .           0/r32/eax   .               .                 # subtract *ecx from eax
    # . restore registers
    59/pop-to-ecx
$space-remaining-in-stream:end:
    # . epilogue
    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
    5d/pop-to-ebp
    c3/return

stream-size:  # f: (addr stream byte) -> n/eax: int
    # . prologue
    55/push-ebp
    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
    # . save registers
    51/push-ecx
    # return f->write
    8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .                         1/r32/ecx   8/disp8         .                 # copy *(ebp+8) to ecx
    8b/copy                         0/mod/indirect  1/rm32/ecx    .           .             .           0/r32/eax   .               .                 # copy *ecx to eax
    # . restore registers
    59/pop-to-ecx
$stream-size:end:
    # . epilogue
    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
    5d/pop-to-ebp
    c3/return

# 3-argument variant of _append
_append-3:  # out: (addr byte), outend: (addr byte), s: (addr array byte) -> num_bytes_appended/eax
    # . prologue
    55/push-ebp
    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
    # . save registers
    51/push-ecx
    # if (outend - out < s->size) abort
    # . eax = f->size - f->write - s->size
    8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .                         0/r32/eax   0xc/disp8       .                 # copy *(ebp+12) to eax
    2b/subtract                     1/mod/*+disp8   5/rm32/ebp    .           .             .           0/r32/eax   8/disp8         .                 # subtract *(ebp+8) from eax
    8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .                         1/r32/ecx   0x10/disp8      .                 # copy *(ebp+16) to ecx
    2b/subtract                     0/mod/indirect  1/rm32/ecx    .           .             .           0/r32/eax   .               .                 # subtract *ecx from eax
    # . if (eax < 0) abort
    3d/compare-eax-and  0/imm32
    7c/jump-if-<  $_append-3:abort/disp8
    # eax = _append-4(out, outend, &s->data[0], &s->data[s->size])
    # . . push &s->data[s->size]
    8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .                         0/r32/eax   0x10/disp8      .                 # copy *(ebp+16) to eax
    8b/copy                         0/mod/indirect  0/rm32/eax    .           .             .           1/r32/ecx   .               .                 # copy *eax to ecx
    8d/copy-address                 1/mod/*+disp8   4/rm32/sib    0/base/eax  1/index/ecx   .           1/r32/ecx   4/disp8         .                 # copy eax+ecx+4 to ecx
    51/push-ecx
    # . . push &s->data[0]
    8d/copy-address                 1/mod/*+disp8   0/rm32/eax    .           .             .           1/r32/ecx   4/disp8         .                 # copy eax+4 to ecx
    51/push-ecx
    # . . push outend
    ff          6/subop/push        1/mod/*+disp8   5/rm32/ebp    .           .             .           .           0xc/disp8       .                 # push *(ebp+12)
    # . . push out
    ff          6/subop/push        1/mod/*+disp8   5/rm32/ebp    .           .             .           .           8/disp8         .                 # push *(ebp+8)
    # . . call
    e8/call  _append-4/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0x10/imm32        # add to esp
$_append-3:end:
    # . restore registers
    59/pop-to-ecx
    # . epilogue
    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
    5d/pop-to-ebp
    c3/return

$_append-3:abort:
    (abort "_append-3 about to overflow")  # 3=cyan
    # never gets here

# 4-argument variant of _append
_append-4:  # out: (addr byte), outend: (addr byte), in: (addr byte), inend: (addr byte) -> num_bytes_appended/eax: int
    # . prologue
    55/push-ebp
    89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
    # . save registers
    51/push-ecx
    52/push-edx
    53/push-ebx
    56/push-esi
    57/push-edi
    # num_bytes_appended = 0
    b8/copy-to-eax  0/imm32
    # edi = out
    8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           7/r32/edi   8/disp8         .                 # copy *(ebp+8) to edi
    # edx = outend
    8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           2/r32/edx   0xc/disp8       .                 # copy *(ebp+12) to edx
    # esi = in
    8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           6/r32/esi   0x10/disp8      .                 # copy *(ebp+16) to esi
    # ecx = inend
    8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           1/r32/ecx   0x14/disp8      .                 # copy *(ebp+20) to ecx
$_append-4:loop:
    # if (in >= inend) break
    39/compare                      3/mod/direct    6/rm32/esi    .           .             .           1/r32/ecx   .               .                 # compare esi with ecx
    73/jump-if-addr>=  $_append-4:end/disp8
    # if (out >= outend) abort  # just to catch test failures fast
    39/compare                      3/mod/direct    7/rm32/edi    .           .             .           2/r32/edx   .               .                 # compare edi with edx
    0f 83/jump-if-addr>=  $_append-4:abort/disp32
    # *out = *in
    8a/copy-byte                    0/mod/indirect  6/rm32/esi    .           .             .           3/r32/BL    .               .                 # copy byte at *esi to BL
    88/copy-byte                    0/mod/indirect  7/rm32/edi    .           .             .           3/r32/BL    .               .                 # copy byte at BL to *edi
    # ++num_bytes_appended
    40/increment-eax
    # ++in
    46/increment-esi
    # ++out
    47/increment-edi
    eb/jump  $_append-4:loop/disp8
$_append-4:end:
    # . restore registers
    5f/pop-to-edi
    5e/pop-to-esi
    5b/pop-to-ebx
    5a/pop-to-edx
    59/pop-to-ecx
    # . epilogue
    89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
    5d/pop-to-ebp
    c3/return

$_append-4:abort:
    (draw-text-wrapping-right-then-down-from-cursor-over-full-screen 0 "_append-4: stream full at " 3 0)  # 3=cyan
    (draw-int32-hex-wrapping-right-then-down-from-cursor-over-full-screen 0 %eax 3 0)
    (abort "")
    # never gets here

# . . vim:nowrap:textwidth=0