From e1aab2e0a37016b0a892405467697d68cdba467f Mon Sep 17 00:00:00 2001
From: "B. Watson" <urchlay@slackware.uk>
Date: Wed, 9 Nov 2022 22:59:11 -0500
Subject: Keep drunkwalk and lineaddrs_l/h from crossing page boundaries (3%
 speedup).

---
 dla.s        | 24 ++++--------------------
 nextpage.inc |  7 +++++++
 2 files changed, 11 insertions(+), 20 deletions(-)
 create mode 100644 nextpage.inc

diff --git a/dla.s b/dla.s
index 12724d7..e1429e9 100644
--- a/dla.s
+++ b/dla.s
@@ -9,6 +9,7 @@
 
  .include "atari.inc"
  .include "xex.inc"
+ .include "nextpage.inc"
 
  loadaddr = $2000
  screen = $4000 ; must be on a x000 (4K) boundary
@@ -452,6 +453,7 @@ plot:
  sta (pixptr),y
  rts
 
+ nextpage
  .include "drunkwalk.s"
 
 ;;; Subroutine: drawseed
@@ -632,6 +634,7 @@ seeds_h: .byte >(seed_point-1),>(seed_plus-1),>(seed_4pt-1),>(seed_long-1)
  ; table of addresses, for each line on the screen. bloats the
  ; code by 384 bytes, but compared to calculating the address, is
  ; twice as fast!
+ nextpage
 lineaddrs_l:
  laddr .set pixarray
  .repeat 170
@@ -639,6 +642,7 @@ lineaddrs_l:
   laddr .set laddr + 170
  .endrep
 
+ nextpage
 lineaddrs_h:
  laddr .set pixarray
  .repeat 170
@@ -646,26 +650,6 @@ lineaddrs_h:
   laddr .set laddr + 170
  .endrep
 
- ; tables to replace X coord => mask-and-offset calculations.
-xoffsets:
- xoffs .set 0
- .repeat 32
-  .repeat 8
-   .byte xoffs
-  .endrep
-  xoffs .set xoffs + 1
- .endrep
-
-xmasks:
- .repeat 32
-  .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
diff --git a/nextpage.inc b/nextpage.inc
new file mode 100644
index 0000000..7e13042
--- /dev/null
+++ b/nextpage.inc
@@ -0,0 +1,7 @@
+
+; fill to the start of the next page.
+ .macro nextpage
+  .repeat ((>(*)+1)*256)-*
+   .byte 0
+  .endrep
+ .endmacro
-- 
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