https://github.com/akkartik/mu/blob/main/linux/random.subx

     1 # Repeatedly read 32-bit numbers from /dev/random, print them to stdout.
     2 #
     3 # To run:
     4 #   $ bootstrap/bootstrap translate [01]*.subx apps/random.subx -o apps/random
     5 #   $ bootstrap/bootstrap run random
     6
     7 == code 0x09000000
     8 #   instruction                     effective address                                                   register    displacement    immediate
     9 # . op          subop               mod             rm32          base        index         scale       r32
    10 # . 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
    11
    12 Entry:
    13     # stream/esi = syscall(open, "/dev/null", O_RDONLY, 0)  # we can't use 'fd' because it looks like a hex byte
    14     bb/copy-to-ebx  Filename/imm32
    15     b9/copy-to-ecx  0/imm32/rdonly
    16     ba/copy-to-edx  0x180/imm32/fixed-perms
    17     e8/call  syscall_open/disp32
    18     # . stream = eax
    19     89/copy                         3/mod/direct    6/rm32/esi    .           .             .           0/r32/eax   .               .                 # copy eax to esi
    20
    21 $loop:
    22
    23     # syscall(read, Stream, N, 4)
    24     89/copy                         3/mod/direct    3/rm32/ebx    .           .             .           6/r32/esi   .               .                 # copy esi to ebx
    25     b9/copy-to-ecx  N/imm32
    26     ba/copy-to-edx  4/imm32/size
    27     e8/call  syscall_read/disp32
    28
    29     # write-int32-hex-buffered(Stdout, *N)
    30     # . . push args
    31     ff          6/subop/push        0/mod/indirect  5/rm32/.disp32            .             .           .           N/disp32                          # push *N
    32     68/push  Stdout/imm32
    33     # . . call
    34     e8/call  write-int32-hex-buffered/disp32
    35
    36     # write-buffered(Stdout, Newline)
    37     # . . push args
    38     68/push  Newline/imm32
    39     68/push  Stdout/imm32
    40     # . . call
    41     e8/call  write-buffered/disp32
    42     # . . discard args
    43     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
    44
    45     eb/jump  $loop/disp8
    46
    47     # syscall(exit, 0)
    48     bb/copy-to-ebx  0/imm32
    49     e8/call  syscall_exit/disp32
    50
    51 == data 0x0a000000
    52
    53 N:
    54     0/imm32
    55 Filename:
    56     2f 64 65 76 2f 72 61 6e 64 6f 6d 00
    57 #   /  d  e  v  /  r  a  n  d  o  m  null
    58
    59 # . . vim:nowrap:textwidth=0