From 02aa2d0c6af003deaaf330e519a3e85384986168 Mon Sep 17 00:00:00 2001
From: Brandon Wright <bearoso@gmail.com>
Date: Wed, 6 Mar 2019 20:17:07 -0600
Subject: [PATCH] Use a lookup table. A little faster.

---
 gfx.h       | 23 +++++++----------------
 globals.cpp |  2 ++
 ppu.cpp     |  8 ++++++++
 3 files changed, 17 insertions(+), 16 deletions(-)

diff --git a/gfx.h b/gfx.h
index 77eb344d..9bcc8b6f 100644
--- a/gfx.h
+++ b/gfx.h
@@ -125,6 +125,7 @@ struct SLineMatrixData
 extern uint16		BlackColourMap[256];
 extern uint16		DirectColourMaps[8][256];
 extern uint8		mul_brightness[16][32];
+extern uint8		brightness_cap[64];
 extern struct SBG	BG;
 extern struct SGFX	GFX;
 
@@ -132,8 +133,6 @@ extern struct SGFX	GFX;
 #define V_FLIP		0x8000
 #define BLANK_TILE	2
 
-#include "ppu.h"
-
 #define COLOR_ADD1_2(C1, C2) \
 	((((((C1) & RGB_REMOVE_LOW_BITS_MASK) + \
 	((C2) & RGB_REMOVE_LOW_BITS_MASK)) >> 1) + \
@@ -147,20 +146,12 @@ extern struct SGFX	GFX;
 
 inline uint16 COLOR_ADD(uint16 C1, uint16 C2)
 {
-	int r1, g1, b1, r2, g2, b2;
-	int cap = mul_brightness[PPU.Brightness][31];
-	DECOMPOSE_PIXEL(C1, r1, g1, b1);
-	DECOMPOSE_PIXEL(C2, r2, g2, b2);
-	r1 += r2;
-	if (r1 > cap)
-		r1 = cap;
-	g1 += g2;
-	if (g1 > cap)
-		g1 = cap;
-	b1 += b2;
-	if (b1 > cap)
-		b1 = cap;
-	return BUILD_PIXEL(r1, g1, b1);
+    int r1, g1, b1, r2, g2, b2;
+    DECOMPOSE_PIXEL(C1, r1, g1, b1);
+    DECOMPOSE_PIXEL(C2, r2, g2, b2);
+    return BUILD_PIXEL(brightness_cap[r1 + r2],
+                       brightness_cap[g1 + g2],
+                       brightness_cap[b1 + b2]);
 }
 
 #define COLOR_SUB1_2(C1, C2) \
diff --git a/globals.cpp b/globals.cpp
index 645c42a2..b671cf58 100644
--- a/globals.cpp
+++ b/globals.cpp
@@ -144,6 +144,8 @@ uint8 mul_brightness[16][32] =
 	  0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f }
 };
 
+uint8 brightness_cap[64];
+
 uint8 S9xOpLengthsM0X0[256] =
 {
 //  0  1  2  3  4  5  6  7  8  9  A  B  C  D  E  F
diff --git a/ppu.cpp b/ppu.cpp
index a0ded291..6bca9dc4 100644
--- a/ppu.cpp
+++ b/ppu.cpp
@@ -189,6 +189,14 @@ void S9xFixColourBrightness (void)
 {
 	IPPU.XB = mul_brightness[PPU.Brightness];
 
+	for (int i = 0; i < 64; i++)
+	{
+		if (i > IPPU.XB[0x1f])
+			brightness_cap[i] = IPPU.XB[0x1f];
+		else
+			brightness_cap[i] = i;
+	}
+
 	for (int i = 0; i < 256; i++)
 	{
 		IPPU.Red[i]   = IPPU.XB[(PPU.CGDATA[i])       & 0x1f];