# Mu - subx/examples/ex3.subx

     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