108write.subx - mu - Soul of a tiny new machine. More thorough tests → More comprehensible and rewrite-friendly software → More resilient society.

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312	# 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

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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