1 # Primitives for screen control.
 2 #
 3 # We need to do this in machine code because Mu doesn't have global variables
 4 # yet (for the start of video memory).
 5 
 6 == code
 7 
 8 pixel-on-real-screen:  # x: int, y: int, color: int
 9     # . prologue
10     55/push-ebp
11     89/<- %ebp 4/r32/esp
12     # . save registers
13     50/push-eax
14     51/push-ecx
15     # bounds checks
16     8b/-> *(ebp+8) 0/r32/eax
17     3d/compare-eax-and 0/imm32
18     7c/jump-if-< $pixel-on-real-screen:end/disp8
19     3d/compare-eax-and 0x400/imm32/screen-width=1024
20     7d/jump-if->= $pixel-on-real-screen:end/disp8
21     8b/-> *(ebp+0xc) 0/r32/eax
22     3d/compare-eax-and 0/imm32
23     7c/jump-if-< $pixel-on-real-screen:end/disp8
24     3d/compare-eax-and 0x300/imm32/screen-height=768
25     7d/jump-if->= $pixel-on-real-screen:end/disp8
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