https://github.com/akkartik/mu/blob/main/linux/apps/ex14.subx
 1 # Multiply 2 numbers.
 2 #
 3 # To run:
 4 #   $ bootstrap/bootstrap translate apps/ex14.subx -o ex14
 5 #   $ bootstrap/bootstrap run ex14
 6 # Expected result:
 7 #   $ echo $?
 8 #   6
 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  1/imm32
17     b9/copy-to-ecx  2/imm32
18     bb/copy-to-ebx  3/imm32
19 
20     69/multiply                     3/mod/direct    1/rm32/ecx    .           .             .           3/r32/ebx                   3/imm32           # ebx = ecx * 3
21 
22 $exit:
23     # exit(ebx)
24     e8/call  syscall_exit/disp32
25 
26 # . . vim:nowrap:textwidth=0