From b5df9d8071b076e65c22d4080fa7394c73b2b660 Mon Sep 17 00:00:00 2001
From: "B. Watson" <yalhcru@gmail.com>
Date: Sat, 15 May 2021 12:18:41 -0400
Subject: Multiple sinking speeds (costs 13 bytes, now 8821)

---
 draw_lorcha.s | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

(limited to 'draw_lorcha.s')

diff --git a/draw_lorcha.s b/draw_lorcha.s
index c3a5c38..07c4afe 100644
--- a/draw_lorcha.s
+++ b/draw_lorcha.s
@@ -3,6 +3,8 @@
 ; Lorcha (boat), a type of sailing vessel having a Chinese
 ; junk rig on a Portuguese or European style hull.
 
+ .include "atari.inc"
+
  .import _jsleep
  .export _draw_lorcha, _sink_lorcha, _damage_lorcha, _clear_lorcha, _flash_lorcha
 
@@ -19,9 +21,6 @@ lorcha_pos_hi:
  .byte >320, >328, >336, >344, >352
  .byte >640, >648, >656, >664, >672
 
-; Atari OS's pointer to start of screen RAM
- SAVMSC = $58
-
 ; ZP working variables start at $d4, aka FR0 (floating point reg 0).
  temp = $d4
  andmask = temp
@@ -29,6 +28,7 @@ lorcha_pos_hi:
  destptr = $d6
  lcount = $d8
  which = $d9
+ sinkdelay = $da
 
 ; clrtobot.s needs these:
  .exportzp destptr
@@ -113,6 +113,15 @@ _sink_lorcha:
  lda #6
  sta lcount
 
+ ; set sinkdelay to 3, 5, or 7 jiffies
+@rnd:
+ lda RANDOM
+ eor RTCLOK+2
+ and #$06
+ beq @rnd
+ ora #1
+ sta sinkdelay
+
 sinkloop:
  ldx which
  jsr setup_destptr
@@ -124,9 +133,9 @@ sinkloop:
  adc #0
  sta destptr+1
 
- ; delay for several jiffies
+ ; delay for sinkdelay jiffies
  ldx #0
- lda #7
+ lda sinkdelay
  jsr _jsleep
 
  ldx #6 ; line loop counter
-- 
cgit v1.2.3