58 lines
1.4 KiB
NASM
58 lines
1.4 KiB
NASM
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; generic rectangle drawing routines
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; draw a filled rectangle to a framebuffer
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; inputs:
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; r0: X coordinate of top-left
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; r1: Y coordinate of top-left
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; r2: X size
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; r3: Y size
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; r4: color
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; r5: pointer to framebuffer
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; r6: framebuffer width (pixels)
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; outputs:
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; none
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draw_filled_rectangle_generic:
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push r0
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push r1
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push r2
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push r3
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push r4
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push r5
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push r6
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push r7
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; calculate pointer to the framebuffer
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mul r6, 4 ; 4 bytes per pixel
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mul r1, r6 ; 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 r5, r0
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mov r0, r5 ; r0: pointer to framebuffer
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mov r7, r6
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mov r6, r2
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mul r6, 4 ; multiply the X size by 4, since 4 bytes per pixel
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draw_filled_rectangle_generic_y_loop:
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mov r5, r2 ; x counter
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draw_filled_rectangle_generic_x_loop:
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mov [r0], r4
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add r0, 4 ; increment framebuffer pointer
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dec r5
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ifnz jmp draw_filled_rectangle_generic_x_loop ; loop if there are still more X pixels to draw
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sub r0, r6 ; return to the beginning of this line
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add r0, r7 ; increment to the next line
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dec r3
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ifnz jmp draw_filled_rectangle_generic_y_loop ; loop if there are still more Y pixels to draw
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pop r7
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pop r6
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pop r5
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pop r4
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pop r3
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pop r2
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pop r1
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pop r0
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ret
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