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                                                   operand     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   # result: EBX = 0
15   bb/copy-to-EBX  0/imm32
16   # counter: ECX = 1
17   b9/copy-to-ECX  1/imm32
18 
19 $loop:
20   # while (counter <= 10)
21   81          7/subop/compare     3/mod/direct    1/rm32/ECX    .           .             .           .           .               0xa/imm32         # compare ECX
22   7f/jump-if-greater  $exit/disp8
23   # result += counter
24   01/add                          3/mod/direct    3/rm32/EBX    .           .             .           1/r32/ECX   .               .                 # add ECX to EBX
25   # ++counter
26   41/inc-ECX
27   # loop
28   eb/jump  $loop/disp8
29 
30 $exit:
31   # exit(EBX)
32   b8/copy-to-EAX  1/imm32
33   cd/syscall  0x80/imm8
34 
35 # vim:nowrap:textwidth=0