From 5490d869dfb3f1be9393bec1ef251dab060293b3 Mon Sep 17 00:00:00 2001
From: Toni Wilen <twilen@winuae.net>
Date: Sat, 14 Jan 2023 15:59:57 +0200
Subject: [PATCH] Color change and sprite buffer limit checks.

---
 custom.cpp        | 29 ++++++++++++++++++++++++++---
 include/drawing.h |  2 +-
 2 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/custom.cpp b/custom.cpp
index 33086e37..d7d43399 100644
--- a/custom.cpp
+++ b/custom.cpp
@@ -153,6 +153,7 @@ static bool nosignal_trigger;
 int display_reset;
 static evt_t line_start_cycles;
 static bool initial_frame;
+static evt_t custom_color_write_cycle;
 
 #define LOF_TOGGLES_NEEDED 3
 //#define NLACE_CNT_NEEDED 50
@@ -546,7 +547,7 @@ static struct draw_info line_drawinfo[2][2 * (MAXVPOS + MAXVPOS_WRAPLINES) + 1];
 #define COLOR_TABLE_SIZE (MAXVPOS + MAXVPOS_WRAPLINES) * 2
 static struct color_entry color_tables[2][COLOR_TABLE_SIZE];
 
-static int next_sprite_entry = 0;
+static int next_sprite_entry = 0, last_sprite_entry = 0;
 static int prev_next_sprite_entry;
 static int next_sprite_forced = 1;
 
@@ -997,6 +998,10 @@ static void record_color_change2(int hpos, int regno, uae_u32 value)
 		return;
 	}
 
+	if (next_color_change > MAX_REG_CHANGE - 30) {
+		return;
+	}
+
 	int pos = hpos < 0 ? -hpos : hpos_to_diwx(hpos);
 
 	// AGA has extra hires pixel delay in color changes
@@ -5022,6 +5027,11 @@ static void record_sprite(int num, int sprxp, uae_u16 *data, uae_u16 *datb, unsi
 	int attachment;
 	int spr_width;
 
+	// do nothing if buffer is full (shouldn't happen normally)
+	if (next_sprite_entry >= last_sprite_entry) {
+		return;
+	}
+
 	half = 0;
 	dbl = sprite_buffer_res - sprres;
 	if (dbl < 0) {
@@ -9173,6 +9183,13 @@ bool get_custom_color_reg(int colreg, uae_u8 *r, uae_u8 *g, uae_u8 *b)
 static void COLOR_WRITE(int hpos, uae_u16 v, int num)
 {
 	bool colzero = false;
+
+	// skip color register write color change state update if color register was already written in same cycle
+	// fast CPU modes can write tens of thousands of color registers in single frame.
+	evt_t c = get_cycles() & ~(CYCLE_UNIT - 1);
+	bool samecycle = c == custom_color_write_cycle;
+	custom_color_write_cycle = c;
+
 #ifdef AGA
 	if (aga_mode) {
 		int r,g,b;
@@ -9214,7 +9231,9 @@ static void COLOR_WRITE(int hpos, uae_u16 v, int num)
 		}
 
 		/* Call this with the old table still intact. */
-		record_color_change(hpos, colreg, cval);
+		if (!samecycle) {
+			record_color_change(hpos, colreg, cval);
+		}
 		remembered_color_entry = -1;
 		current_colors.color_regs_aga[colreg] = cval;
 		current_colors.acolors[colreg] = getxcolor(cval);
@@ -9237,7 +9256,9 @@ static void COLOR_WRITE(int hpos, uae_u16 v, int num)
 		}
 
 		/* Call this with the old table still intact. */
-		record_color_change(hpos, num, v);
+		if (!samecycle) {
+			record_color_change(hpos, num, v);
+		}
 		remembered_color_entry = -1;
 		current_colors.color_regs_ecs[num] = v;
 		current_colors.acolors[num] = getxcolor (v);
@@ -10765,6 +10786,7 @@ void init_hardware_for_drawing_frame(void)
 	}
 	prev_next_sprite_entry = next_sprite_entry;
 	next_sprite_entry = 0;
+	last_sprite_entry = MAX_SPR_PIXELS - 1;
 
 	next_lineno = calculate_lineno(vpos);
 	last_color_change = 0;
@@ -13362,6 +13384,7 @@ void custom_reset(bool hardreset, bool keyboardreset)
 	copper_dma_change_cycle = -1;
 	blitter_dma_change_cycle = -1;
 	sprite_dma_change_cycle_on = -1;
+	custom_color_write_cycle = -1;
 
 	if (hardreset || savestate_state) {
 		maxhpos = ntsc ? MAXHPOS_NTSC : MAXHPOS_PAL;
diff --git a/include/drawing.h b/include/drawing.h
index 04895b99..c303a8e5 100644
--- a/include/drawing.h
+++ b/include/drawing.h
@@ -259,7 +259,7 @@ struct color_change {
 #define MAXVPOS_WRAPLINES 10
 
 /* No divisors for MAX_PIXELS_PER_LINE; we support AGA and SHRES sprites */
-#define MAX_SPR_PIXELS (((MAXVPOS + MAXVPOS_WRAPLINES) * 2 + 1) * MAX_PIXELS_PER_LINE)
+#define MAX_SPR_PIXELS ((((MAXVPOS + MAXVPOS_WRAPLINES) * 2 + 1) * MAX_PIXELS_PER_LINE) / 16)
 
 struct sprite_entry
 {
-- 
2.47.3