From: ian <ian>
Date: Sat, 23 Oct 2004 11:05:06 +0000 (+0000)
Subject: faster
X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ijackson/git?a=commitdiff_plain;h=2eee6fdee8916ae37de9bff0cdd33d664a065111;p=trains.git

faster
---

diff --git a/layout/subseg2display.c b/layout/subseg2display.c
index 31a8ba8..fa4e020 100644
--- a/layout/subseg2display.c
+++ b/layout/subseg2display.c
@@ -194,15 +194,13 @@ static unsigned reverse_bits_in_byte(unsigned a) {
 }
 
 static void angle_to_colour(double result[3],
-			    double angle /* in units of 2pi radians< <1.0 */,
-			    int reverse) {
+			    int angle_i /* [0..63> */) {
   int s;
-  double f, u, d, U, D;
+  double angle, f, u, d, U, D;
 
-  angle *= 6.0;
+  angle= angle_i / 64.0 * 6.0;
   s= floor(angle);
   f= angle - s;
-  if (reverse) { s += 3; s %= 6; }
   
   u= f * 0.5;
   U= u + 0.5;
@@ -221,6 +219,15 @@ static void angle_to_colour(double result[3],
   }
 }
 
+static double anglemap[64][3];
+
+static void angle_to_colour_init(void) {
+  int i;
+  
+  for (i=0; i<64; i++)
+    angle_to_colour(anglemap[i],i);
+}
+
 static void process(void) {
   int i;
   unsigned char rgbob[3];
@@ -233,10 +240,11 @@ static void process(void) {
   for (i=0; i<3; i++)
     rgbob[i]= background.rgb[i] * 255.0;
 
+  angle_to_colour_init();
+
   for (row=0; row<rows; row++)
     for (col=0; col<cols; col++) {
       unsigned char rgbi[3], rgbo[3];
-      double rgbod[3];
 
       if (fread(rgbi,1,3,encodingfile)!=3) {
 	if (ferror(encodingfile)) { perror("reading"); exit(12); }
@@ -248,8 +256,8 @@ static void process(void) {
 	if (fwrite(rgbob,1,3,stdout)!=3) { perror("filling"); exit(12); }
 	
       } else {
-	int segnum, movfeatpos, movfeatposix, red, blue, green, ix;
-	double rgbdirn[3], angle, alpha;
+	int segnum, movfeatpos, movfeatposix, red, blue, green, ix, angle;
+	double *rgbdirn, alpha;
 	struct result *r;
 
 	red= rgbi[0];
@@ -257,7 +265,7 @@ static void process(void) {
 	blue= reverse_bits_in_byte(rgbi[2]);
       
 	if (red & 0x03) badformat("reserved bits set in red");
-	angle= ((red >> 2) & 0x3f) / 64.0;
+	angle= ((red >> 2) & 0x3f);
 
 	segnum= blue | ((green & 0xc0) << 2);
 	movfeatpos= green & 0x3f;
@@ -273,14 +281,14 @@ static void process(void) {
 
 	r= &idinfo[ix];
 
-	angle_to_colour(rgbdirn, angle, r->alpha < 0);
+	rgbdirn= anglemap[ angle ^ (r->alpha < 0 ? 32 : 0) ];
 	alpha= fabs(r->alpha);
 
-	for (i=0; i<3; i++)
-	  rgbod[i]= alpha * rgbdirn[i] + (1.0 - alpha) * r->rgb[i];
-
-	for (i=0; i<3; i++)
-	  rgbo[i]= rgbod[i] * 255.0;
+	for (i=0; i<3; i++) {
+	  double v;
+	  v= alpha * rgbdirn[i] + (1.0 - alpha) * r->rgb[i];
+	  rgbo[i]= v * 255.0;
+	}
 
 	if (fwrite(rgbo,1,3,stdout)!=3) { perror("writing"); exit(12); }
       }