From: John Tsiombikas <nuclear@member.fsf.org>
Date: Mon, 17 May 2021 22:50:37 +0000 (+0300)
Subject: the sin lut was too small for any kind of reasonable resolution in high
X-Git-Url: http://git.mutantstargoat.com/user/nuclear/?p=retrobench;a=commitdiff_plain;h=3ac76817d27b4ffc90f04a97c8714afb165eebc2

the sin lut was too small for any kind of reasonable resolution in high
framerates
---

diff --git a/src/rbench.c b/src/rbench.c
index 7202c1a..8b9e23f 100644
--- a/src/rbench.c
+++ b/src/rbench.c
@@ -33,7 +33,7 @@ void cleanup(void)
 
 #define XORRGB(x, y, zoom, r, g, b) \
 	do { \
-		int xor = (((x) - fb_width/2) * (zoom) >> 10) ^ (((y) - fb_height/2) * (zoom) >> 10); \
+		int xor = (((x) - fb_width/2) * (zoom) >> 16) ^ (((y) - fb_height/2) * (zoom) >> 16); \
 		(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 >> 5) * fb_width >> 7;
-	yoffs = SIN(time_msec >> 4) * fb_height >> 8;
-	zoom = ((SIN(time_msec >> 4) + 256) << 1) + 512;
+	xoffs = COS(time_msec >> 3) * fb_width >> 15;
+	yoffs = SIN(time_msec >> 2) * fb_height >> 16;
+	zoom = (SIN(time_msec >> 5) >> 1) + 65536;
 
 	switch(fb_bpp) {
 	case 15:
diff --git a/src/util.h b/src/util.h
index 9f0eb4d..6880649 100644
--- a/src/util.h
+++ b/src/util.h
@@ -14,8 +14,8 @@ typedef unsigned int uint32_t;
 
 extern int sinlut[];
 
-#define SIN(x) sinlut[(x) & 0xff]
-#define COS(x) sinlut[((x) + 64) & 0xff]
+#define SIN(x) sinlut[(x) & 0x3ff]
+#define COS(x) sinlut[((x) + 512) & 0x3ff]
 
 int mask_to_shift(unsigned int mask);
 
diff --git a/tools/lutgen.c b/tools/lutgen.c
index a573de1..a2cc1ed 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<256; i++) {
-		float x = sin((float)i / 128.0f * M_PI);
-		printf("\t.long %d\n", (int)(x * 256.0f));
+	for(i=0; i<1024; i++) {
+		float x = sin((float)i / 512.0f * M_PI);
+		printf("\t.long %d\n", (int)(x * 65536.0f));
 	}
 	return 0;
 }