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Copyright (c) 2021, Andinus <andinus@nand.sh>

Permission to use, copy, modify, and/or distribute this software for any
purpose with or without fee is hereby granted, provided that the above
copyright notice and this permission notice appear in all copies.

THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
/a> 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239
# write-stream: like write, but write streams rather than strings

== 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

# main:
    # manual test
#?     # write-stream(stdout, _test-stream2)
#?     68/push  _test-stream2/imm32
#?     68/push  1/imm32/stdout
#?     e8/call write-stream/disp32
    # automatic test
#?     e8/call test-write-stream-appends/disp32
    e8/call  run-tests/disp32  # 'run-tests' is a function created automatically by SubX. It calls all functions that start with 'test-'.
    # syscall(exit, Num-test-failures)
    8b/copy                         0/mod/indirect  5/rm32/.disp32            .             .           3/r32/EBX   Num-test-failures/disp32          # copy *Num-test-failures to EBX
    b8/copy-to-EAX  1/imm32
    cd/syscall  0x80/imm8

write-stream:  # f : fd or (address stream), s : (address stream) -> <void>
    # . prolog
    55/push-EBP
    89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
    # if (f < 0x08000000) _write-stream(f, s), return  # f can't be a user-mode address, so treat it as a kernel file descriptor
    81          7/subop/compare     1/mod/*+disp8   4/rm32/sib    5/base/EBP  4/index/none  .           .           8/disp8         0x08000000/imm32  # compare *(EBP+8)
    7d/jump-if-greater-or-equal  $write-stream:fake/disp8
    # . . push args
    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  .           .           8/disp8         .                 # push *(EBP+8)
    # . . call
    e8/call  _write-stream/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
    eb/jump  $write-stream:end/disp8
$write-stream:fake:
    # otherwise, treat 'f' as a stream to append to
    # . save registers
    50/push-EAX
    56/push-ESI
    57/push-EDI
    # ESI = f
    8b/copy                         1/mod/*+disp8   4/rm32/sib    5/base/EBP  4/index/none              6/r32/ESI   8/disp8         .                 # copy *(EBP+8) to ESI
    # EDI = s
    8b/copy                         1/mod/*+disp8   4/rm32/sib    5/base/EBP  4/index/none              7/r32/EDI   0xc/disp8       .                 # copy *(EBP+12) to EDI
    # EAX = _append-4(&f->data[f->write], &f->data[f->length], &s->data[s->read], &s->data[s->write])
    # push &s->data[s->write]
    8b/copy                         0/mod/indirect  7/rm32/EDI    .           .             .           0/r32/EAX   .               .                 # copy *EDI to EAX
    8d/copy-address                 1/mod/*+disp8   4/rm32/sib    7/base/EDI  0/index/EAX   .           0/r32/EAX   0xc/disp8       .                 # copy EDI+EAX+12 to EAX
    50/push-EAX
    # push &s->data[s->read]
    8b/copy                         1/mod/*+disp8   7/rm32/EDI    .           .             .           0/r32/EAX   4/disp8         .                 # copy *(EDI+4) to EAX
    8d/copy-address                 1/mod/*+disp8   4/rm32/sib    7/base/EDI  0/index/EAX   .           0/r32/EAX   0xc/disp8       .                 # copy EDI+EAX+12 to EAX
    50/push-EAX
    # push &f->data[f->length]
    8b/copy                         1/mod/*+disp8   6/rm32/ESI    .           .             .           0/r32/EAX   8/disp8         .                 # copy *(ESI+8) to EAX
    8d/copy-address                 1/mod/*+disp8   4/rm32/sib    6/base/ESI  0/index/EAX   .           0/r32/EAX   0xc/disp8       .                 # copy ESI+EAX+12 to EAX
    50/push-EAX
    # push &f->data[f->write]
    8b/copy                         0/mod/indirect  6/rm32/ESI    .           .             .           0/r32/EAX   .               .                 # copy *ESI to EAX
    8d/copy-address                 1/mod/*+disp8   4/rm32/sib    6/base/ESI  0/index/EAX   .           0/r32/EAX   0xc/disp8       .                 # copy ESI+EAX+12 to EAX
    50/push-EAX
    # . . call
    e8/call  _append-4/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               0x10/imm32        # add to ESP
    # f->write += EAX
    01/add                          0/mod/indirect  6/rm32/ESI    .           .             .           0/r32/EAX   .               .                 # add EAX to *ESI
    # s->read += EAX
    01/add                          1/mod/*+disp8   7/rm32/EDI    .           .             .           0/r32/EAX   4/disp8         .                 # add EAX to *(EDI+4)
    # . restore registers
    5f/pop-to-EDI
    5e/pop-to-ESI
    58/pop-to-EAX
$write-stream:end:
    # . epilog
    89/copy                         3/mod/direct    4/rm32/ESP    .           .             .           5/r32/EBP   .               .                 # copy EBP to ESP
    5d/pop-to-EBP
    c3/return

_write-stream:  # fd : int, s : (address stream) -> <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
    51/push-ECX
    52/push-EDX
    53/push-EBX
    56/push-ESI
    57/push-EDI
    # ESI = s
    8b/copy                         1/mod/*+disp8   4/rm32/sib    5/base/EBP  4/index/none  .           6/r32/ESI   0xc/disp8       .                 # copy *(EBP+12) to ESI
    # EDI = s->read
    8b/copy                         1/mod/*+disp8   6/rm32/ESI    .           .             .           7/r32/EDI   4/disp8         .                 # copy *(ESI+4) to EDI
    # EDX = s->write
    8b/copy                         0/mod/indirect  6/rm32/ESI    .           .             .           2/r32/EDX   .               .                 # copy *ESI to EDX
    # syscall(write, fd, &s->data[s->read], s->write-s->read)
    # fd : EBX
    8b/copy                         1/mod/*+disp8   4/rm32/sib    5/base/EBP  4/index/none  .           3/r32/EBX   8/disp8         .                 # copy *(EBP+8) to EBX
    # data : ECX = &s->data[s->read]
    8d/copy-address                 1/mod/*+disp8   4/rm32/sib    6/base/ESI  7/index/EDI   .           1/r32/ECX   0xc/disp8       .                 # copy ESI+EDI+12 to ECX
    # size : EDX = s->write - s->read
    29/subtract                     3/mod/direct    2/rm32/EDX    .           .             .           7/r32/EDI   .               .                 # subtract EDI from EDX
    # syscall
    b8/copy-to-EAX  4/imm32/write
    cd/syscall  0x80/imm8
    # . restore registers
    5f/pop-to-EDI
    5e/pop-to-ESI
    5b/pop-to-EBX
    5a/pop-to-EDX
    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-write-stream-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
    # clear-stream(_test-stream2)
    # . . push args
    68/push  _test-stream2/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-stream2, "Ab")
    # . . push args
    68/push  "Ab"/imm32
    68/push  _test-stream2/imm32
    # . . call
    e8/call  write/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
    # write-stream(_test-stream, _test-stream2)
    # . . push args
    68/push  _test-stream2/imm32
    68/push  _test-stream/imm32
    # . . call
    e8/call  write-stream/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-stream-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-stream-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
    # clear-stream(_test-stream2)
    # . . push args
    68/push  _test-stream2/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-stream2, "C")
    # . . push args
    68/push  "C"/imm32
    68/push  _test-stream2/imm32
    # . . call
    e8/call  write/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
    # write-stream(_test-stream, _test-stream2)
    # . . push args
    68/push  _test-stream2/imm32
    68/push  _test-stream/imm32
    # . . call
    e8/call  write-stream/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
    # write(_test-stream2, "D")
    # . . push args
    68/push  "D"/imm32
    68/push  _test-stream2/imm32
    # . . call
    e8/call  write/disp32
    # . . discard args
    81          0/subop/add         3/mod/direct    4/rm32/ESP    .           .             .           .           .               8/imm32           # add to ESP
    # write-stream(_test-stream, _test-stream2)
    # . . push args
    68/push  _test-stream2/imm32
    68/push  _test-stream/imm32
    # . . call
    e8/call  write-stream/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-stream-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-stream2:
    # current write index
    04 00 00 00
    # current read index
    01 00 00 00
    # length (= 8)
    08 00 00 00
    # data
    41 42 43 44 00 00 00 00  # 8 bytes

# . . vim:nowrap:textwidth=0