; Constant definitions

.def GFX_TMP r58

.def GFX_TMP2 r59

.def GFX_TMP_BYTE r58b

; void gfx_draw_pixel(int x, int y, byte color)

; x : 17

; y : 13

; color : 12

.label gfx_draw_pixel

.def gfx_draw_pixel_offset r0

.def gfx_draw_pixel_arg_x 17

.def gfx_draw_pixel_arg_y 13

.def gfx_draw_pixel_arg_color 12

; backup register

rpush gfx_draw_pixel_offset

; calculate offset into vram

loadi gfx_draw_pixel_offset, VRAM_ADDRESS

load GFX_TMP, gfx_draw_pixel_arg_x

add gfx_draw_pixel_offset, GFX_TMP

load GFX_TMP, gfx_draw_pixel_arg_y

loadi GFX_TMP2, VRAM_WIDTH

mul GFX_TMP, GFX_TMP2

add gfx_draw_pixel_offset, GFX_TMP

; write the color

load GFX_TMP_BYTE, gfx_draw_pixel_arg_color

write gfx_draw_pixel_offset, GFX_TMP_BYTE

; restore registers

rpop gfx_draw_pixel_offset

ret