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| author | Kartik Agaram <vc@akkartik.com> | 2021-01-09 17:04:21 -0800 |
|---|---|---|
| committer | Kartik Agaram <vc@akkartik.com> | 2021-01-09 18:28:14 -0800 |
| commit | 7f8770ae082a723faae89faea0dce6635feb7cdb (patch) | |
| tree | 4955853fdd8c1f70197453b8ba339b950376908f /baremetal/103grapheme.subx | |
| parent | dbd7082a0ed09ee06401d0af06ce24e89e87b189 (diff) | |
| download | mu-7f8770ae082a723faae89faea0dce6635feb7cdb.tar.gz | |
7490 - baremetal: draw a grapheme to screen
Diffstat (limited to 'baremetal/103grapheme.subx')
| -rw-r--r-- | baremetal/103grapheme.subx | 70 |
1 files changed, 70 insertions, 0 deletions
diff --git a/baremetal/103grapheme.subx b/baremetal/103grapheme.subx new file mode 100644 index 00000000..934aac51 --- /dev/null +++ b/baremetal/103grapheme.subx @@ -0,0 +1,70 @@ +draw-grapheme: # screen: (addr screen), g: grapheme, x: int, y: int, color: int + # . prologue + 55/push-ebp + 89/<- %ebp 4/r32/esp + # . save registers + 50/push-eax + 51/push-ecx + 52/push-edx + 53/push-ebx + 56/push-esi + # var letter-bitmap/esi = font[g] + 8b/-> *(ebp+0xc) 6/r32/esi + c1 4/subop/shift-left %esi 4/imm8 + 8d/copy-address *(esi+0x8800) 6/r32/esi # font-start + # if (letter-bitmap >= 0x9000) return # characters beyond ASCII currently not supported + 81 7/subop/compare %esi 0x9000/imm32 + 7d/jump-if->= $draw-grapheme:end/disp8 + # edx = y + 8b/-> *(ebp+0x14) 2/r32/edx + # var ymax/ebx: int = y + 16 + 8b/-> *(ebp+0x14) 3/r32/ebx + 81 0/subop/add %ebx 0x10/imm32 + { + # if (y >= ymax) break + 39/compare %edx 3/r32/ebx + 7d/jump-if->= break/disp8 + # eax = x + 7 + 8b/-> *(ebp+0x10) 0/r32/eax + 81 0/subop/add %eax 7/imm32 + # var xmin/ecx: int = x + 8b/-> *(ebp+0x10) 1/r32/ecx + # var row-bitmap/ebx: int = *letter-bitmap + 53/push-ebx + 8b/-> *esi 3/r32/ebx + { + # if (x < xmin) break + 39/compare %eax 1/r32/ecx + 7c/jump-if-< break/disp8 + # shift LSB from row-bitmap into carry flag (CF) + c1 5/subop/shift-right-logical %ebx 1/imm8 + # if LSB, draw a pixel + { + 73/jump-if-not-CF break/disp8 + (pixel *(ebp+8) %eax %edx *(ebp+0x18)) + } + # --x + 48/decrement-eax + # + eb/jump loop/disp8 + } + # reclaim row-bitmap + 5b/pop-to-ebx + # ++y + 42/increment-edx + # next bitmap row + 46/increment-esi + # + eb/jump loop/disp8 + } +$draw-grapheme:end: + # . restore registers + 5e/pop-to-esi + 5b/pop-to-ebx + 5a/pop-to-edx + 59/pop-to-ecx + 58/pop-to-eax + # . epilogue + 89/<- %esp 5/r32/ebp + 5d/pop-to-ebp + c3/return |