https://github.com/akkartik/mu/blob/main/linux/ex13.subx

     1 # Compare 3 and 3.
     2 #
     3 # To run:
     4 #   $ bootstrap/bootstrap translate apps/ex13.subx -o apps/ex13
     5 #   $ bootstrap/bootstrap run ex13
     6 # Expected result:
     7 #   $ echo $?
     8 #   1
     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     b8/copy-to-eax  3/imm32
    17     3d/compare-eax-and  3/imm32
    18     0f 94/set-if-=                  3/mod/direct    3/rm32/ebx    .           .             .           .           .               .                 # set ebx to ZF
    19     81 4/subop/and                  3/mod/direct    3/rm32/ebx    .           .             .           .           .               0xff/imm32        # AND with eax
    20
    21 $exit:
    22     # exit(ebx)
    23     e8/call  syscall_exit/disp32
    24
    25 # . . vim:nowrap:textwidth=0