From faf9179c10e1619845912d746de85ff082a58c72 Mon Sep 17 00:00:00 2001
From: Vince Weaver <vince@deater.net>
Date: Mon, 4 Apr 2022 19:17:37 -0400
Subject: [PATCH] lemm: keep pointer on screen

would crash spectacularly when we'd go off the edge
---
 games/lemm/draw_pointer.s        |  2 +-
 games/lemm/hgr_partial_restore.s |  3 ++-
 games/lemm/keyboard.s            | 32 ++++++++++++--------------------
 3 files changed, 15 insertions(+), 22 deletions(-)

diff --git a/games/lemm/draw_pointer.s b/games/lemm/draw_pointer.s
index 69756edd..e7b0c15f 100644
--- a/games/lemm/draw_pointer.s
+++ b/games/lemm/draw_pointer.s
@@ -88,7 +88,7 @@ erase_pointer:
 	lda	CURSOR_Y
 	sta	SAVED_Y1
 	clc
-	adc	#16
+	adc	#14
 	sta	SAVED_Y2
 
 	lda     CURSOR_X
diff --git a/games/lemm/hgr_partial_restore.s b/games/lemm/hgr_partial_restore.s
index 0d5cda71..acdfce50 100644
--- a/games/lemm/hgr_partial_restore.s
+++ b/games/lemm/hgr_partial_restore.s
@@ -14,7 +14,8 @@ hgr_partial_restore:
 	ldx	SAVED_Y2			; handle wrap around
 	cpx	#192
 	bcc	partial_restore_yloop		; assume > 192 off screen negative
-	ldx	#0
+
+	ldx	#0			; X is end y-co-ord?
 
 partial_restore_yloop:
 
diff --git a/games/lemm/keyboard.s b/games/lemm/keyboard.s
index c6066330..cf4dce7a 100644
--- a/games/lemm/keyboard.s
+++ b/games/lemm/keyboard.s
@@ -120,11 +120,8 @@ check_left:
 	cmp	#8			; left key
 	bne	check_right
 left_pressed:
-	lda	CURSOR_X		; if 41<x<$FE don't decrement
-	cmp	#41
-	bcc	do_dec_cursor_x
-	cmp	#$FE
-	bcc	done_left_pressed
+	lda	CURSOR_X		; if X==0 don't decrement
+	beq	done_left_pressed
 do_dec_cursor_x:
 	dec	CURSOR_X
 done_left_pressed:
@@ -136,11 +133,9 @@ check_right:
 	cmp	#$15			; right key
 	bne	check_up
 right_pressed:
-	lda	CURSOR_X		; if 40<x<$FE don't increment
-	cmp	#40
-	bcc	do_inc_cursor_x
-	cmp	#$FE
-	bcc	done_right_pressed
+	lda	CURSOR_X		; if X>=38 don't increment
+	cmp	#38
+	bcs	done_right_pressed
 do_inc_cursor_x:
 	inc	CURSOR_X
 done_right_pressed:
@@ -152,11 +147,8 @@ check_up:
 	cmp	#$0B			; up key
 	bne	check_down
 up_pressed:
-	lda	CURSOR_Y		; if 191<y<$F0 don't decrement
-	cmp	#191
-	bcc	do_dec_cursor_y
-	cmp	#$F0
-	bcc	done_up_pressed
+	lda	CURSOR_Y		; if Y==0 don't increment
+	beq	done_up_pressed
 do_dec_cursor_y:
 	dec	CURSOR_Y
 	dec	CURSOR_Y
@@ -172,11 +164,11 @@ check_down:
 	cmp	#$0A
 	bne	check_escape
 down_pressed:
-	lda	CURSOR_Y		; if 191<y<$EE don't decrement
-	cmp	#191
-	bcc	do_inc_cursor_y
-	cmp	#$EE
-	bcc	done_down_pressed
+	lda	CURSOR_Y		; if Y>=176 then don't inc?
+	cmp	#176			; cursor is 14 in size
+;	bcc	do_inc_cursor_y
+;	cmp	#$EE
+	bcs	done_down_pressed
 do_inc_cursor_y:
 	inc	CURSOR_Y
 	inc	CURSOR_Y