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uxn/examples/line.usm
2021-02-14 19:43:33 -08:00

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1.9 KiB
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( draw routines )
:dev/r fff8 ( std read port )
:dev/w fff9 ( std write port )
;x_ 2 ;y_ 2 ;color 1
;x0 2 ;y0 2 ;x1 2 ;y1 2 ;dx 2 ;dy 2 ;err1 2 ;err2 2
|0100 @RESET
( set dev/write to screen )
#01 =dev/w ( set dev/write to sprite )
( positive )
#01 ,color STR
+0030 ,x0 STR2 +0040 ,y0 STR2
+0100 ,x1 STR2 +0060 ,y1 STR2
,line JSR
#02 ,color STR
+0020 ,x0 STR2 +0010 ,y0 STR2
+0090 ,x1 STR2 +0070 ,y1 STR2
,line JSR
#03 ,color STR
+0010 ,x0 STR2 +0040 ,y0 STR2
+0070 ,x1 STR2 +0060 ,y1 STR2
,line JSR
( draw control points )
#02 ,color STR
,x0 LDR2 ,y0 LDR2 ,putpixel JSR
,x1 LDR2 ,y1 LDR2 ,putpixel JSR
,redraw JSR
BRK
@line
,x0 LDR2 ,x_ STR2 ,y0 LDR2 ,y_ STR2 ( start at x0,y0 )
,x1 LDR2 ,x0 LDR2 ,diff16sub JSR ,dx STR2 ( int dx = abs[x1 - x0] )
,y1 LDR2 ,y0 LDR2 ,diff16sub JSR -0001 MULS2 ,dy STR2 ( int dy = -abs[y1 - y0] )
,dx LDR2 ,dy LDR2 ADDS2 ,err1 STR2 ( int err1 = dx + dy, e2; )
@lineloop
,x_ LDR2 ,y_ LDR2 ,putpixel JSR ( draw )
@line-x
,err1 LDR2 +0002 MULS2 ,err2 STR2 ( e2 = 2 * err; )
,err2 LDR2 ,dy LDR2 LTHS2 ,line-y ROT JMP? POP2 ( e2 >= dy )
,err1 LDR2 ,dy LDR2 ADDS2 ,err1 STR2 ( err1 += dy; )
,x_ LDR2 +0001 ADDS2 ,x_ STR2 ( y0 += y0 < y1 ? 1 : -1; )
@line-y
,err2 LDR2 ,dx LDR2 GTHS2 ,line-end ROT JMP? POP2 ( e2 <= dx )
,err1 LDR2 ,dx LDR2 ADDS2 ,err1 STR2 ( err1 += dx; )
,y_ LDR2 +0001 ADDS2 ,y_ STR2 ( y0 += y0 < y1 ? 1 : -1; )
@line-end
,x_ LDR2 ,x1 LDR2 NEQS2 ,lineloop ROT JMP? POP2 ( loop )
RTS
@redraw
#0000 IOW2
#0000 IOW2
#00 IOW
#01 IOW
RTS
@putpixel
IOW2 ( y short )
IOW2 ( x short )
,color LDR IOW ( color byte )
#00 IOW ( redraw byte )
RTS
@diff16
OVR2 OVR2 GTH2 ,diff16sub ROT JMP? POP2
SWP2 @diff16sub SUB2
RTS
|c000 @FRAME BRK
|d000 @ERROR BRK
|FFFA .RESET .FRAME .ERROR