From 523febfe756566b414051a392d9ab0e5c1649f49 Mon Sep 17 00:00:00 2001
From: John Tsiombikas <nuclear@member.fsf.org>
Date: Thu, 20 May 2021 15:47:06 +0300
Subject: [PATCH] improved the xor effect slightly

---
 src/rbench.c   |   16 ++++++++--------
 src/util.h     |    6 +++---
 tools/lutgen.c |    6 +++---
 3 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/src/rbench.c b/src/rbench.c
index 8b9e23f..34a26c6 100644
--- a/src/rbench.c
+++ b/src/rbench.c
@@ -31,9 +31,9 @@ void cleanup(void)
 {
 }
 
-#define XORRGB(x, y, zoom, r, g, b) \
+#define XORRGB(x, y, dx, dy, zoom, r, g, b) \
 	do { \
-		int xor = (((x) - fb_width/2) * (zoom) >> 16) ^ (((y) - fb_height/2) * (zoom) >> 16); \
+		int xor = ((((x) - fb_width/2) * (zoom) >> 16) + (dx)) ^ ((((y) - fb_height/2) * (zoom) >> 16) + (dy)); \
 		(r) = xor >> 2; \
 		(g) = xor >> 1; \
 		(b) = xor; \
@@ -46,9 +46,9 @@ void redraw(void)
 	uint16_t *fbptr16;
 	uint32_t *fbptr32;
 
-	xoffs = COS(time_msec >> 3) * fb_width >> 15;
-	yoffs = SIN(time_msec >> 2) * fb_height >> 16;
-	zoom = (SIN(time_msec >> 5) >> 1) + 65536;
+	xoffs = COS(time_msec >> 2) * fb_width >> 14;
+	yoffs = SIN(time_msec >> 1) * fb_height >> 15;
+	zoom = (SIN(time_msec >> 3) << 1) + 0x18000;
 
 	switch(fb_bpp) {
 	case 15:
@@ -56,7 +56,7 @@ void redraw(void)
 		fbptr16 = framebuf;
 		for(i=0; i<fb_height; i++) {
 			for(j=0; j<fb_width; j++) {
-				XORRGB(j + xoffs, i + yoffs, zoom, r, g, b);
+				XORRGB(j, i, xoffs, yoffs, zoom, r, g, b);
 				*fbptr16++ = (((r >> 3) << fb_rshift) & fb_rmask) |
 					(((g >> 2) << fb_gshift) & fb_gmask) |
 					(((b >> 3) << fb_bshift) & fb_bmask);
@@ -69,7 +69,7 @@ void redraw(void)
 		fbptr = framebuf;
 		for(i=0; i<fb_height; i++) {
 			for(j=0; j<fb_width; j++) {
-				XORRGB(j + xoffs, i + yoffs, zoom, r, g, b);
+				XORRGB(j, i, xoffs, yoffs, zoom, r, g, b);
 				*fbptr++ = r;
 				*fbptr++ = g;
 				*fbptr++ = b;
@@ -82,7 +82,7 @@ void redraw(void)
 		fbptr32 = framebuf;
 		for(i=0; i<fb_height; i++) {
 			for(j=0; j<fb_width; j++) {
-				XORRGB(j + xoffs, i + yoffs, zoom, r, g, b);
+				XORRGB(j, i, xoffs, yoffs, zoom, r, g, b);
 				*fbptr32++ = (((r) << fb_rshift) & fb_rmask) |
 					(((g) << fb_gshift) & fb_gmask) |
 					(((b) << fb_bshift) & fb_bmask);
diff --git a/src/util.h b/src/util.h
index 69d9d1e..633ccbf 100644
--- a/src/util.h
+++ b/src/util.h
@@ -35,10 +35,10 @@ typedef unsigned long intptr_t;
 	 ((x) << 24))
 
 
-extern int sinlut[];
+extern short sinlut[];
 
-#define SIN(x) sinlut[(x) & 0x3ff]
-#define COS(x) sinlut[((x) + 256) & 0x3ff]
+#define SIN(x) (int)sinlut[(x) & 0x7ff]
+#define COS(x) (int)sinlut[((x) + 512) & 0x7ff]
 
 int mask_to_shift(unsigned int mask);
 
diff --git a/tools/lutgen.c b/tools/lutgen.c
index a2cc1ed..65a349f 100644
--- a/tools/lutgen.c
+++ b/tools/lutgen.c
@@ -10,9 +10,9 @@ int main(void)
 	puts("\t.globl sinlut");
 	puts("_sinlut:");
 	puts("sinlut:");
-	for(i=0; i<1024; i++) {
-		float x = sin((float)i / 512.0f * M_PI);
-		printf("\t.long %d\n", (int)(x * 65536.0f));
+	for(i=0; i<2048; i++) {
+		float x = sin((float)i / 1024.0f * M_PI);
+		printf("\t.word %d\n", (short)(x * 32767.0f));
 	}
 	return 0;
 }
-- 
1.7.10.4