33 lines
648 B
NASM
33 lines
648 B
NASM
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; generic pixel drawing routines
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; draw a pixel to a framebuffer
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; inputs:
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; r0: X coordinate
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; r1: Y coordinate
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; r2: color
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; r3: pointer to framebuffer
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; r4: framebuffer width (pixels)
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; outputs:
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; none
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draw_pixel_generic:
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push r0
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push r1
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push r3
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push r4
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; calculate pointer to the framebuffer
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mul r4, 4 ; 4 bytes per pixel
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mul r1, r4 ; y * width * 4
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mul r0, 4 ; x * 4
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add r0, r1 ; y * width * 4 + (x * 4)
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add r3, r0
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mov r0, r3 ; r0: pointer to framebuffer
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mov [r0], r2
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pop r4
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pop r3
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pop r1
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pop r0
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ret
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