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Moved outcode calculation in a separate module.

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git-svn-id: svn://svn.cc65.org/cc65/trunk@4462 b7a2c559-68d2-44c3-8de9-860c34a00d81
This commit is contained in:
uz 2009-11-12 15:10:45 +00:00
parent 884aff9191
commit 80b81549fd
3 changed files with 113 additions and 103 deletions
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1
libsrc/tgi/Makefile
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@ -67,6 +67,7 @@ S_OBJS = tgi-kernel.o \
tgi_linepop.o \
tgi_lineto.o \
tgi_map_mode.o \
tgi_outcode.o \
tgi_outtext.o \
tgi_outtextxy.o \
tgi_popxy.o \

117
libsrc/tgi/tgi_clippedline.s
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@ -18,15 +18,11 @@
.bss
; Line coordinates. Must be set before calling tgi_clippedline
tgi_clip_x1: .res 2
tgi_clip_y1: .res 2
tgi_clip_x2: .res 2
tgi_clip_y2: .res 2
; Outcodes for both ends
tgi_clip_o1: .res 1
tgi_clip_o2: .res 1
; Line deltas
tgi_clip_d: .res 1
tgi_clip_dx: .res 2
tgi_clip_dy: .res 2
@ -34,91 +30,6 @@ tgi_clip_dy: .res 2
tgi_clip_sign: .res 1
;----------------------------------------------------------------------------
; outcode constants.
CLIP_NONE = $00
CLIP_LEFT = $01
CLIP_RIGHT = $02
CLIP_BOTTOM = $04
CLIP_TOP = $08
;----------------------------------------------------------------------------
; Generate a Cohen Sutherland outcode
;
; void outcode ()
; {
; unsigned char o = 0;
; if (Y < 0) {
; o = CLIP_BOTTOM;
; } else if (Y >= yres) {
; o = CLIP_TOP;
; }
; if (X < 0) {
; o |= CLIP_LEFT;
; } else if (X >= xres) {
; o |= CLIP_RIGHT;
; }
; return o;
; }
.code
.proc outcode
lda #CLIP_NONE
sta tmp1
; Check Y coordinate
lda tgi_clip_y1+1,y ; High byte of Y1
bmi L2 ; Jump if bottom clip
ldx tgi_clip_y1,y ; Low byte of Y1
cpx _tgi_yres
sbc _tgi_yres+1
bvs L1
eor #$80
L1: bpl L4
lda #CLIP_TOP ; Top clipping necessary
bne L3
L2: lda #CLIP_BOTTOM
L3: sta tmp1 ; Save temp outcode
; Check X coordinate
L4: lda tgi_clip_x1+1,y ; High byte of X1
bmi L7 ; Jump if left clip
ldx tgi_clip_x1,y ; Low byte of X1
cpx _tgi_xres
sbc _tgi_xres+1
bvs L5
eor #$80
L5: bmi L6
; No right or left clipping necessary
lda tmp1
rts
; Need right clipping
L6: lda #CLIP_RIGHT
ora tmp1
rts
; Need left clipping
L7: lda #CLIP_LEFT
ora tmp1
rts
.endproc
;----------------------------------------------------------------------------
; Calculate outcodes for both ends of the line
;
@ -127,7 +38,7 @@ L7: lda #CLIP_LEFT
.proc outcode1
ldy #0
jsr outcode
jsr tgi_outcode
sta tgi_clip_o1
rts
@ -136,8 +47,8 @@ L7: lda #CLIP_LEFT
.code
.proc outcode2
ldy #(tgi_clip_y2 - tgi_clip_y1)
jsr outcode
ldy #<(tgi_clip_y2 - tgi_clip_y1)
jsr tgi_outcode
sta tgi_clip_o2
rts
@ -256,7 +167,7 @@ L7: lda #CLIP_LEFT
; Generate the absolute value of y/a and calculate the sign of the final
; result
jsr prepare_coord
; All values are positive now (dx/dy have been made positive in calcdeltas)
@ -381,7 +292,7 @@ HaveDeltas:
; Need to clip X1/Y1
lsr a ; Check for CLIP_LEFT
lsr a ; Check for TGI_CLIP_LEFT
bcc L3
; tgi_clip_y1 += (0 - tgi_clip_x1) * tgi_clip_dy / tgi_clip_dx;
@ -391,7 +302,7 @@ HaveDeltas:
tax
beq L4
L3: lsr a ; Check for CLIP_RIGHT
L3: lsr a ; Check for TGI_CLIP_RIGHT
bcc L5
; tgi_clip_y1 += (tgi_xmax - tgi_clip_x1) * tgi_clip_dy / tgi_clip_dx;
@ -423,7 +334,7 @@ L4: tay
lda tgi_clip_o1
lsr a
lsr a
L5: lsr a ; Check for CLIP_BOTTOM
L5: lsr a ; Check for TGI_CLIP_BOTTOM
bcc L6
; tgi_clip_x1 = (0 - tgi_clip_y1) * tgi_clip_dx / tgi_clip_dy;
@ -433,7 +344,7 @@ L5: lsr a ; Check for CLIP_BOTTOM
tax
beq L7
L6: lsr a ; Check for CLIP_TOP
L6: lsr a ; Check for TGI_CLIP_TOP
bcc L8
; tgi_clip_x1 += (tgi_ymax - tgi_clip_y1) * tgi_clip_dx / tgi_clip_dy;
@ -471,7 +382,7 @@ L10: lda tgi_clip_o2
; Need to clip X2/Y2
lsr a ; Check for CLIP_LEFT
lsr a ; Check for TGI_CLIP_LEFT
bcc L11
; tgi_clip_y2 += (0 - tgi_clip_x2) * tgi_clip_dy / tgi_clip_dx;
@ -481,7 +392,7 @@ L10: lda tgi_clip_o2
tax
beq L12
L11: lsr a ; Check for CLIP_RIGHT
L11: lsr a ; Check for TGI_CLIP_RIGHT
bcc L13
; tgi_clip_y2 += (tgi_xmax - tgi_clip_x2) * tgi_clip_dy / tgi_clip_dx;
@ -513,7 +424,7 @@ L12: tay
lda tgi_clip_o2
lsr a
lsr a
L13: lsr a ; Check for CLIP_BOTTOM
L13: lsr a ; Check for TGI_CLIP_BOTTOM
bcc L14
; tgi_clip_x2 += (0 - tgi_clip_y2) * tgi_clip_dx / tgi_clip_dy;
@ -523,7 +434,7 @@ L13: lsr a ; Check for CLIP_BOTTOM
tax
beq L15
L14: lsr a ; Check for CLIP_TOP
L14: lsr a ; Check for TGI_CLIP_TOP
bcc L16
; tgi_clip_x2 += (tgi_ymax - tgi_clip_y2) * tgi_clip_dx / tgi_clip_dy;

98
libsrc/tgi/tgi_outcode.s Normal file
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@ -0,0 +1,98 @@
;
; Ullrich von Bassewitz, 2009-10-25
;
; Generates clipping outcodes for Cohen Sutherland and others.
;
.include "tgi-kernel.inc"
.include "zeropage.inc"
;----------------------------------------------------------------------------
; Data
.bss
; Clipping coordinates.
tgi_clip_x1: .res 2
tgi_clip_y1: .res 2
tgi_clip_x2: .res 2
tgi_clip_y2: .res 2
;----------------------------------------------------------------------------
; Generate a Cohen Sutherland outcode
;
; void outcode ()
; {
; unsigned char o = 0;
; if (Y < 0) {
; o = TGI_CLIP_BOTTOM;
; } else if (Y >= yres) {
; o = TGI_CLIP_TOP;
; }
; if (X < 0) {
; o |= TGI_CLIP_LEFT;
; } else if (X >= xres) {
; o |= TGI_CLIP_RIGHT;
; }
; return o;
; }
;
; The function return the outcode in A and the flags for the outcode are
; correctly set.
;
.code
.proc tgi_outcode
lda #TGI_CLIP_NONE
sta tmp1
; Check Y coordinate
lda tgi_clip_y1+1,y ; High byte of Y1
bmi L2 ; Jump if bottom clip
ldx tgi_clip_y1,y ; Low byte of Y1
cpx _tgi_yres
sbc _tgi_yres+1
bvs L1
eor #$80
L1: bpl L4
lda #TGI_CLIP_TOP ; Top clipping necessary
bne L3
L2: lda #TGI_CLIP_BOTTOM
L3: sta tmp1 ; Save temp outcode
; Check X coordinate
L4: lda tgi_clip_x1+1,y ; High byte of X1
bmi L7 ; Jump if left clip
ldx tgi_clip_x1,y ; Low byte of X1
cpx _tgi_xres
sbc _tgi_xres+1
bvs L5
eor #$80
L5: bmi L6
; No right or left clipping necessary
lda tmp1
rts
; Need right clipping
L6: lda #TGI_CLIP_RIGHT
ora tmp1
rts
; Need left clipping
L7: lda #TGI_CLIP_LEFT
ora tmp1
rts
.endproc