1 # Rudimentary test harness
  2 
  3 == code
  4 #   instruction                     effective address                                                   register    displacement    immediate
  5 # . op          subop               mod             rm32          base        index         scale       r32
  6 # . 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
  7 
  8 Entry:  # manual test
  9     # check-ints-equal(34, 34)
 10     # . . push args
 11     68/push  "error in check-ints-equal"/imm32
 12     68/push  34/imm32
 13     68/push  34/imm32
 14     # . . call
 15     e8/call  check-ints-equal/disp32
 16     # . . discard args
 17     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
 18     # syscall(exit, 0)
 19     bb/copy-to-ebx  0/imm32
 20     b8/copy-to-eax  1/imm32/exit
 21     cd/syscall  0x80/imm8
 22 
 23 # print msg to stderr if a != b, otherwise print "."
 24 check-ints-equal:  # a : int, b : int, msg : (address array byte)
 25     # . prologue
 26     55/push-ebp
 27     89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
 28     # . save registers
 29     50/push-eax
 30     51/push-ecx
 31     53/push-ebx
 32     # load first 2 args into eax and ebx
 33     8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           0/r32/eax   8/disp8         .                 # copy *(ebp+8) to eax
 34     8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           3/r32/ebx   0xc/disp8       .                 # copy *(ebp+12) to ebx
 35     # if (eax == ebx) success
 36     39/compare                      3/mod/direct    0/rm32/eax    .           .             .           3/r32/ebx   .               .                 # compare eax and ebx
 37     75/jump-if-unequal  $check-ints-equal:else/disp8
 38     # . _write(2/stderr, '.')
 39     # . . push args
 40     68/push  "."/imm32
 41     68/push  2/imm32/stderr
 42     # . . call
 43     e8/call  _write/disp32
 44     # . . discard args
 45     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
 46     # . return
 47     eb/jump  $check-ints-equal:end/disp8
 48     # otherwise print error message
 49 $check-ints-equal:else:
 50     # . _write(2/stderr, msg)
 51     # . . push args
 52     8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           1/r32/ecx   0x10/disp8      .                 # copy *(ebp+16) to ecx
 53     51/push-ecx
 54     68/push  2/imm32/stderr
 55     # . . call
 56     e8/call  _write/disp32
 57     # . . discard args
 58     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
 59     # . _write(2/stderr, Newline)
 60     # . . push args
 61     68/push  Newline/imm32
 62     68/push  2/imm32/stderr
 63     # . . call
 64     e8/call  _write/disp32
 65     # . . discard args
 66     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
 67     # increment Num-test-failures
 68     ff          0/subop/increment   0/mod/indirect  5/rm32/.disp32            .             .           .           Num-test-failures/disp32          # increment *Num-test-failures
 69 $check-ints-equal:end:
 70     # . restore registers
 71     5b/pop-to-ebx
 72     59/pop-to-ecx
 73     58/pop-to-eax
 74     # . epilogue
 75     89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
 76     5d/pop-to-ebp
 77     c3/return
 78 
 79 == data
 80 
 81 # length-prefixed string containing just a single newline
 82 # convenient to have when printing messages and so on
 83 Newline:  # (ref array byte)
 84     # size : int
 85     1/imm32
 86     # data
 87     0a/newline
 88 
 89 # every test failure increments this counter
 90 Num-test-failures:  # int
 91     0/imm32
 92 
 93 # length-prefixed string containing just a single space
 94 Space:  # (ref array byte)
 95     # size : int
 96     1/imm32
 97     # data
 98     20/space
 99 
100 # length-prefixed string containing just a single slash
101 Slash:  # (ref array byte)
102     # size : int
103     1/imm32
104     # data
105     2f/slash
106 
107 # . . vim:nowrap:textwidth=0