1 # Add the first 10 numbers, and return the result in the exit code.
 2 #
 3 # To run (from the subx directory):
 4 #   $ subx translate examples/ex3.subx -o examples/ex3
 5 #   $ subx run examples/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     # result: EBX = 0
16     bb/copy-to-EBX  0/imm32
17     # counter: ECX = 1
18     b9/copy-to-ECX  1/imm32
19 
20 $loop:
21     # while (counter <= 10)
22     81          7/subop/compare     3/mod/direct    1/rm32/ECX    .           .             .           .           .               0xa/imm32         # compare ECX
23     7f/jump-if-greater  $exit/disp8
24     # result += counter
25     01/add                          3/mod/direct    3/rm32/EBX    .           .             .           1/r32/ECX   .               .                 # add ECX to EBX
26     # ++counter
27     41/inc-ECX
28     # loop
29     eb/jump  $loop/disp8
30 
31 $exit:
32     # syscall(exit, EBX)
33     b8/copy-to-EAX  1/imm32/exit
34     cd/syscall  0x80/imm8
35 
36 # . . vim:nowrap:textwidth=0