https://github.com/akkartik/mu/blob/main/linux/ex3.subx

     1 # Add the first 10 numbers, and return the result in the exit code.
     2 #
     3 # To run:
     4 #   $ bootstrap/bootstrap translate apps/ex3.subx -o apps/ex3
     5 #   $ bootstrap/bootstrap run ex3
     6 # Expected result:
     7 #   $ echo $?
     8 #   55
     9
    10 == code
    11 #   instruction                     effective address                                                   register    displacement    immediate
    12 # . op          subop               mod             rm32          base        index         scale       r32
    13 # . 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
    14
    15 Entry:
    16     # result: ebx = 0
    17     bb/copy-to-ebx  0/imm32
    18     # counter: ecx = 1
    19     b9/copy-to-ecx  1/imm32
    20
    21 $loop:
    22     # if (counter > 10) break
    23     81          7/subop/compare     3/mod/direct    1/rm32/ecx    .           .             .           .           .               0xa/imm32         # compare ecx
    24     7f/jump-if->  $exit/disp8
    25     # result += counter
    26     01/add                          3/mod/direct    3/rm32/ebx    .           .             .           1/r32/ecx   .               .                 # add ecx to ebx
    27     # ++counter
    28     41/increment-ecx
    29     # loop
    30     eb/jump  $loop/disp8
    31
    32 $exit:
    33     # exit(ebx)
    34     e8/call  syscall_exit/disp32
    35
    36 # . . vim:nowrap:textwidth=0