https://github.com/akkartik/mu/blob/main/linux/134emit-hex-array.subx

      1 == code
      2 #   instruction                     effective address                                                   register    displacement    immediate
      3 # . op          subop               mod             rm32          base        index         scale       r32
      4 # . 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
      5
      6 # print 'arr' in hex with a space after every byte
      7 emit-hex-array:  # out: (addr buffered-file), arr: (addr array byte)
      8     # . prologue
      9     55/push-ebp
     10     89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
     11     # . save registers
     12     50/push-eax
     13     51/push-ecx
     14     52/push-edx
     15     57/push-edi
     16     # edi = out
     17     8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           7/r32/edi   8/disp8         .                 # copy *(ebp+8) to edi
     18     # edx = arr
     19     8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           2/r32/edx   0xc/disp8       .                 # copy *(ebp+12) to edx
     20     # var curr/ecx: (addr byte) = arr->data
     21     8d/copy-address                 1/mod/*+disp8   2/rm32/edx    .           .             .           1/r32/ecx   4/disp8         .                 # copy edx+4 to ecx
     22     # var max/edx: (addr byte) = &arr->data[arr->size]
     23     8b/copy                         0/mod/indirect  2/rm32/edx    .           .             .           2/r32/edx   .               .                 # copy *edx to edx
     24     01/add                          3/mod/direct    2/rm32/edx    .           .             .           1/r32/ecx   .               .                 # add ecx to edx
     25     # var c/eax: byte = 0
     26     31/xor                          3/mod/direct    0/rm32/eax    .           .             .           0/r32/eax   .               .                 # clear eax
     27 $emit-hex-array:loop:
     28     # if (curr >= width) break
     29     39/compare                      3/mod/direct    1/rm32/ecx    .           .             .           2/r32/edx   .               .                 # compare ecx with edx
     30     73/jump-if-addr>=  $emit-hex-array:end/disp8
     31     # emit-hex(out, c = *curr, width=1)
     32     # . . push args
     33     68/push  1/imm32/width
     34     8a/copy-byte                    0/mod/indirect  1/rm32/ecx    .           .             .           0/r32/AL    .               .                 # copy byte at *ecx to AL
     35     50/push-eax
     36     57/push-edi
     37     # . . call
     38     e8/call  emit-hex/disp32
     39     # . . discard args
     40     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
     41     # ++curr
     42     41/increment-ecx
     43     eb/jump  $emit-hex-array:loop/disp8
     44 $emit-hex-array:end:
     45     # . restore registers
     46     5f/pop-to-edi
     47     5a/pop-to-edx
     48     59/pop-to-ecx
     49     58/pop-to-eax
     50     # . epilogue
     51     89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
     52     5d/pop-to-ebp
     53     c3/return
     54
     55 test-emit-hex-array:
     56     # . prologue
     57     55/push-ebp
     58     89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
     59     # setup
     60     # . clear-stream(_test-output-stream)
     61     # . . push args
     62     68/push  _test-output-stream/imm32
     63     # . . call
     64     e8/call  clear-stream/disp32
     65     # . . discard args
     66     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
     67     # . clear-stream($_test-output-buffered-file->buffer)
     68     # . . push args
     69     68/push  $_test-output-buffered-file->buffer/imm32
     70     # . . call
     71     e8/call  clear-stream/disp32
     72     # . . discard args
     73     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
     74     # var arr/ecx (array byte) = [01, 02, 03]
     75     68/push  0x00030201/imm32  # bytes 01 02 03
     76     68/push  3/imm32/size
     77     89/copy                         3/mod/direct    1/rm32/ecx    .           .             .           4/r32/esp   .               .                 # copy esp to ecx
     78     # emit-hex-array(_test-output-buffered-file, arr)
     79     # . . push args
     80     51/push-ecx
     81     68/push  _test-output-buffered-file/imm32
     82     # . . call
     83     e8/call  emit-hex-array/disp32
     84     # . . discard args
     85     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               8/imm32           # add to esp
     86     # . flush(_test-output-buffered-file)
     87     # . . push args
     88     68/push  _test-output-buffered-file/imm32
     89     # . . call
     90     e8/call  flush/disp32
     91     # . . discard args
     92     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               4/imm32           # add to esp
     93 +-- 33 lines: #?     # dump output -----------------------------------------------------------------------------------------------------------------------------------------
    126     # check-next-stream-line-equal(_test-output-stream, "01 02 03 ", msg)
    127     # . . push args
    128     68/push  "F - test-emit-hex-array"/imm32
    129     68/push  "01 02 03 "/imm32
    130     68/push  _test-output-stream/imm32
    131     # . . call
    132     e8/call  check-next-stream-line-equal/disp32
    133     # . . discard args
    134     81          0/subop/add         3/mod/direct    4/rm32/esp    .           .             .           .           .               0xc/imm32         # add to esp
    135     # . epilogue
    136     89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
    137     5d/pop-to-ebp
    138     c3/return
    139
    140 # . . vim:nowrap:textwidth=0