From: Ian Jackson <ian@liberator.relativity.greenend.org.uk>
Date: Sun, 28 Jun 2009 17:17:28 +0000 (+0100)
Subject: Faster, by cacheing last colour
X-Git-Tag: 1.9.2~90^2~8
X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~yarrgweb/git?p=ypp-sc-tools.db-test.git;a=commitdiff_plain;h=fcb77d1400e798c5154251b44aabdecfc37bf839

Faster, by cacheing last colour
---

diff --git a/pctb/structure.h b/pctb/structure.h
index 0ad92a6..ec399a2 100644
--- a/pctb/structure.h
+++ b/pctb/structure.h
@@ -42,38 +42,45 @@ extern const CanonColourInfo canoncolourinfos[];
 
 CanonImage *alloc_canon_image(int w, int h);
 
-#define CANONICALISE_IMAGE(im,w,h, COMPUTE_RGB) do{		\
-    /* compute_rgb should be a number of statements, or		\
-     * a block, which assigns to				\
-     *   unsigned long rgb;					\
-     * given the values of					\
-     *   int x,y;						\
-     * all of which are anamorphic.  Result is stored in im.	\
-     * The COMPUTE_RGB is executed exactly once for		\
-     * each pixel in reading order.				\
-     */								\
-    (im)= alloc_canon_image((w), (h));				\
-								\
-    int x,y;							\
-    for (y=0; y<(h); y++) {					\
-      for (x=0; x<(w); x++) {					\
-        const CanonColourInfo *cci;				\
-        unsigned long rgb;					\
-	COMPUTE_RGB;						\
-	for (cci=canoncolourinfos; cci->c; cci++) {		\
-	  if (cci->rgb == rgb) {				\
-	    (im)->d[y*(w) + x]= cci->c;				\
-	    break;						\
-	  }							\
-	}							\
-      }								\
-      if (DEBUGP(rect)) {					\
-	fprintf(debug, "%4d ",y);				\
-	fwrite(im->d + y*w, 1,w, debug);			\
-	fputc('\n',debug);					\
-      }								\
-    }								\
-    debug_flush();						\
+#define CANONICALISE_IMAGE(im,w,h, COMPUTE_RGB) do{			\
+    /* compute_rgb should be a number of statements, or			\
+     * a block, which assigns to					\
+     *   unsigned long rgb;						\
+     * given the values of						\
+     *   int x,y;							\
+     * all of which are anamorphic.  Result is stored in im.		\
+     * The COMPUTE_RGB is executed exactly once for			\
+     * each pixel in reading order.					\
+     */									\
+    (im)= alloc_canon_image((w), (h));					\
+									\
+    int x,y;								\
+    unsigned long last_rgb= ~0UL;					\
+    int last_c= -1; 							\
+    for (y=0; y<(h); y++) {						\
+      for (x=0; x<(w); x++) {						\
+        const CanonColourInfo *cci;					\
+        unsigned long rgb;						\
+	COMPUTE_RGB;							\
+	if (rgb == last_rgb) {						\
+	  (im)->d[y*(w) + x]= last_c;					\
+	} else {							\
+	  for (cci=canoncolourinfos; cci->c; cci++) {			\
+	    if (cci->rgb == rgb) {					\
+	      last_rgb= rgb;						\
+	      (im)->d[y*(w) + x]= last_c= cci->c;			\
+	      break;							\
+	    }								\
+	  }								\
+	}								\
+      }									\
+      if (DEBUGP(rect)) {						\
+	fprintf(debug, "%4d ",y);					\
+	fwrite(im->d + y*w, 1,w, debug);				\
+	fputc('\n',debug);						\
+      }									\
+    }									\
+    debug_flush();							\
   }while(0)