aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorB. Watson <urchlay@slackware.uk>2022-11-01 01:27:07 -0400
committerB. Watson <urchlay@slackware.uk>2022-11-01 01:27:07 -0400
commit1cf1a42b0eaf807e69608979772d09dbfe00b9fe (patch)
tree95e07dde2e8c27b7e04e1fc1109caebafd27056c
parentd3481fac922d0915d33eec8da05b05990aad3a58 (diff)
downloaddla-asm-1cf1a42b0eaf807e69608979772d09dbfe00b9fe.tar.gz
fastmasks, ~15% speedup
-rw-r--r--Makefile2
-rw-r--r--dla.s41
2 files changed, 31 insertions, 12 deletions
diff --git a/Makefile b/Makefile
index fb969a8..3109cd9 100644
--- a/Makefile
+++ b/Makefile
@@ -14,7 +14,7 @@ clean:
rm -f dla.xex dlatbl.s dla.list dla.labels *.o
test: all
- atari800 -turbo dla.xex
+ atari800 dla.xex
%.xex: %.s
$(CL65) $(CL65FLAGS) -t none -o $@ $<
diff --git a/dla.s b/dla.s
index 7904af7..3c61064 100644
--- a/dla.s
+++ b/dla.s
@@ -495,6 +495,8 @@ unplot:
; sta part_y
; rts
+oob:
+ rts
;;; Subroutine: drunkwalk
;;; Walk the point around randomly until it either is
;;; adjacent to a set pixel or goes out of bounds.
@@ -547,33 +549,46 @@ dontplot:
; check neighbors. used to be a subroutine, inlined it.
; also inlined plotsetup here.
- ; (-1,0)
- dec cursor_x
ldx cursor_y
lda lineaddrs_l,x
sta pixptr
lda lineaddrs_h,x
sta pixptr+1
+
+ ; 3/4 of the time, we can use a faster code path, check
+ ; (-1,0) and (1,0) at the same time. this happens only when
+ ; both pixels lie within the same byte.
+ ldx cursor_x
+ lda fastmasks,x
+ beq slow_x
+ ldy xoffsets,x
+ and (pixptr),y
+ bne stick
+ beq check_y
+slow_x:
+ ; (-1,0)
ldx cursor_x
+ dex
ldy xoffsets,x
lda xmasks,x
and (pixptr),y
bne stick
; (1,0)
inx
- stx cursor_x
inx
ldy xoffsets,x
lda xmasks,x
and (pixptr),y
bne stick
+check_y:
; (0,-1)
- dec cursor_y
- ldx cursor_y
- lda lineaddrs_l,x
- sta pixptr
- lda lineaddrs_h,x
- sta pixptr+1
+ ldx cursor_y ;3
+ dex ;2
+ lda lineaddrs_l,x ;5
+ sta pixptr ;3
+ lda lineaddrs_h,x ;5
+ sta pixptr+1 ;3
+ ;=21
ldx cursor_x
ldy xoffsets,x
lda xmasks,x
@@ -582,7 +597,7 @@ dontplot:
bne stick
; (0,1)
tya
- ora #$40 ; add 64
+ ora #$40 ; add 64, AKA 2 screen lines
tay
lda (pixptr),y
and pixmask
@@ -590,7 +605,6 @@ dontplot:
jmp drunkwalk ; too far for a branch
stick:
-oob:
rts
;;; Subroutine: drawseed
@@ -800,6 +814,11 @@ xmasks:
.byte $80,$40,$20,$10,$08,$04,$02,$01
.endrep
+fastmasks:
+ .repeat 32
+ .byte $00,$a0,$50,$28,$14,$0a,$05,$00
+ .endrep
+
;;; display list
; ANTIC opcodes
blank8 = $70