From 7b109ab6528bfafa6ac8fd9340e5cc0217bcec50 Mon Sep 17 00:00:00 2001 From: Kartik Agaram Date: Sat, 9 Jan 2021 19:02:23 -0800 Subject: 7494 --- html/baremetal/115write-byte.subx.html | 99 ++++++++++++++++++++++++++++++++++ 1 file changed, 99 insertions(+) create mode 100644 html/baremetal/115write-byte.subx.html (limited to 'html/baremetal/115write-byte.subx.html') diff --git a/html/baremetal/115write-byte.subx.html b/html/baremetal/115write-byte.subx.html new file mode 100644 index 00000000..43cbc843 --- /dev/null +++ b/html/baremetal/115write-byte.subx.html @@ -0,0 +1,99 @@ + + + + +Mu - baremetal/115write-byte.subx + + + + + + + + + + +https://github.com/akkartik/mu/blob/main/baremetal/115write-byte.subx +
+ 1 #   instruction                     effective address                                                   register    displacement    immediate
+ 2 # . op          subop               mod             rm32          base        index         scale       r32
+ 3 # . 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
+ 4 
+ 5 # Write lower byte of 'n' to 'f'.
+ 6 append-byte:  # f: (addr stream byte), n: int
+ 7     # . prologue
+ 8     55/push-ebp
+ 9     89/copy                         3/mod/direct    5/rm32/ebp    .           .             .           4/r32/esp   .               .                 # copy esp to ebp
+10     # . save registers
+11     51/push-ecx
+12     57/push-edi
+13     # edi = f
+14     8b/copy                         1/mod/*+disp8   5/rm32/ebp    .           .             .           7/r32/edi   8/disp8         .                 # copy *(ebp+8) to edi
+15     # ecx = f->write
+16     8b/copy                         0/mod/indirect  7/rm32/edi    .           .             .           1/r32/ecx   .               .                 # copy *edi to ecx
+17     # if (f->write >= f->size) abort
+18     3b/compare                      1/mod/*+disp8   7/rm32/edi    .           .             .           1/r32/ecx   8/disp8         .                 # compare ecx with *(edi+8)
+19     7d/jump-if->=  $append-byte:end/disp8  # TODO: abort
+20 $append-byte:to-stream:
+21     # write to stream
+22     # f->data[f->write] = LSB(n)
+23     31/xor                          3/mod/direct    0/rm32/eax    .           .             .           0/r32/eax   .               .                 # clear eax
+24     8a/copy-byte                    1/mod/*+disp8   5/rm32/ebp    .           .             .           0/r32/AL    0xc/disp8       .                 # copy byte at *(ebp+12) to AL
+25     88/copy-byte                    1/mod/*+disp8   4/rm32/sib    7/base/edi  1/index/ecx   .           0/r32/AL    0xc/disp8       .                 # copy AL to *(edi+ecx+12)
+26     # ++f->write
+27     ff          0/subop/increment   0/mod/indirect  7/rm32/edi    .           .             .           .           .               .                 # increment *edi
+28 $append-byte:end:
+29     # . restore registers
+30     5f/pop-to-edi
+31     59/pop-to-ecx
+32     # . epilogue
+33     89/copy                         3/mod/direct    4/rm32/esp    .           .             .           5/r32/ebp   .               .                 # copy ebp to esp
+34     5d/pop-to-ebp
+35     c3/return
+36 
+37 # . . vim:nowrap:textwidth=0
+
+ + + -- cgit 1.4.1-2-gfad0