https://github.com/akkartik/mu/blob/master/subx/050_write.subx

     1 # _write: write to a file descriptor (fd)
     2
     3 == code
     4 #   instruction                     effective address                                                   register    displacement    immediate
     5 # . op          subop               mod             rm32          base        index         scale       r32
     6 # . 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
     7
     8 Entry:  # just exit; can't test _write just yet
     9     # . syscall(exit, 0)
    10     bb/copy-to-EBX  0/imm32
    11     b8/copy-to-EAX  1/imm32/exit
    12     cd/syscall  0x80/imm8
    13
    14 _write:  # fd : int, s : (address array byte) -> <void>
    15     # . prolog
    16     55/push-EBP
    17     89/copy                         3/mod/direct    5/rm32/EBP    .           .             .           4/r32/ESP   .               .                 # copy ESP to EBP
    18     # . save registers
    19     50/push-EAX
    20     51/push-ECX
    21     52/push-EDX
    22     53/push-EBX
    23     # syscall(write, fd, (data) s+4, (size) *s)
    24     # . fd : EBX
    25     8b/copy                         1/mod/*+disp8   5/rm32/EBP    .           .             .           3/r32/EBX   8/disp8         .                 # copy *(EBP+8) to EBX
    26     # . data : ECX = s+4
    27     8b/copy                         1/mod/*+disp8   5/rm32/EBP    .           .             .           1/r32/ECX   0xc/disp8       .                 # copy *(EBP+12) to ECX
    28     81          0/subop/add         3/mod/direct    1/rm32/ECX    .           .             .           .           .               4/imm32           # add to ECX
    29     # . size : EDX = *s
    30     8b/copy                         1/mod/*+disp8   5/rm32/EBP    .           .             .           2/r32/EDX   0xc/disp8       .                 # copy *(EBP+12) to EDX
    31     8b/copy                         0/mod/indirect  2/rm32/EDX    .           .             .           2/r32/EDX   .               .                 # copy *EDX to EDX
    32     # . syscall
    33     b8/copy-to-EAX  4/imm32/write
    34     cd/syscall  0x80/imm8
    35 $_write:end:
    36     # . restore registers
    37     5b/pop-to-EBX
    38     5a/pop-to-EDX
    39     59/pop-to-ECX
    40     58/pop-to-EAX
    41     # . epilog
    42     89/copy                         3/mod/direct    4/rm32/ESP    .           .             .           5/r32/EBP   .               .                 # copy EBP to ESP
    43     5d/pop-to-EBP
    44     c3/return
    45
    46 # . . vim:nowrap:textwidth=0