1 # TODO: read-byte-buffered
 2 
 3 # Return next byte value in eax, with top 3 bytes cleared.
 4 # Abort on reaching end of stream.
 5 read-byte:  # s: (addr stream byte) -> result/eax: byte
 6     # . prologue
 7     55/push-ebp
 8     89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
 9     # . save registers
10     51/push-ecx
11     56/push-esi
12     # esi = s
13     8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           6/r32/esi   8/disp8         .                 # copy *(ebp+8) to esi
14     # ecx = s->read
15     8b/copy                         1/mod/*+disp8   6/rm32/esi    .           .             .           1/r32/ecx   4/disp8         .                 # copy *(esi+4) to ecx
16     # if (f->read >= f->write) abort
17     3b/compare                      0/mod/indirect  6/rm32/esi    .           .             .           1/r32/ecx   .               .                 # compare ecx with *esi
18     0f 8d/jump-if->=  $read-byte:end/disp32  # TODO: abort
19     # result = f->data[f->read]
20     31/xor                          3/mod/direct    0/rm32/eax    .           .             .           0/r32/eax   .               .                 # clear eax
21     8a/copy-byte                    1/mod/*+disp8   4/rm32/sib    6/base/esi  1/index/ecx   .           0/r32/AL    0xc/disp8       .                 # copy byte at *(esi+ecx+12) to AL
22     # ++f->read
23     ff          0/subop/increment   1/mod/*+disp8   6/rm32/esi    .           .             .           .           4/disp8         .                 # increment *(esi+4)
24 $read-byte:end:
25     # . restore registers
26     5e/pop-to-esi
27     59/pop-to-ecx
28     # . epilogue
29     89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
30     5d/pop-to-ebp
31     c3/return
32 
33 # . . vim:nowrap:textwidth=0