--- cbp.c	2002/03/08 02:44:35	1.1
+++ cbp.c	2003/03/09 12:00:58	1.12
@@ -3,19 +3,84 @@
 
 cbpFuncPtr calc_cbp;
 
-uint32_t calc_cbp_c(const int16_t codes[6][64])
+/*
+ * Returns a field of bits that indicates non zero ac blocks
+ * for this macro block
+ */
+
+/* naive C */
+uint32_t
+calc_cbp_plain(const int16_t codes[6 * 64])
 {
-    uint32_t i, j;
-    uint32_t cbp = 0;
+	int i, j;
+	uint32_t cbp = 0;
 
-    for (i = 0; i < 6; i++) {
-		for (j = 1; j < 64/4; j+=4) {
-			if (codes[i][j]  |codes[i][j+1]|
-				codes[i][j+2]|codes[i][j+3]) {
-				cbp |= 1 << (5 - i);
+	for (i = 0; i < 6; i++) {
+		for (j=1; j<64;j++) {
+			if (codes[64*i+j]) {
+            	cbp |= 1 << (5-i);
 				break;
 			}
 		}
-    }
-    return cbp;
+	}
+	return cbp;
 }
+
+/* optimized C */
+uint32_t
+calc_cbp_c(const int16_t codes[6 * 64])
+{
+	unsigned int i=6;
+	uint32_t cbp = 0;
+
+/* uses fixed relation: 4*codes = 1*codes64 */
+/* if prototype is changed (e.g. from int16_t to something like int32) this routine 
+   has to be changed! */
+
+	do  {
+		uint64_t *codes64 = (uint64_t*)codes;	/* the compiler doesn't really make this */
+		uint32_t *codes32 = (uint32_t*)codes;	/* variables, just "addressing modes" */
+
+		cbp += cbp; 
+        if (codes[1] || codes32[1]) {
+			cbp++;
+		}
+        else if (codes64[1] | codes64[2] | codes64[3]) {
+			cbp++;
+		}
+        else if (codes64[4] | codes64[5] | codes64[6] | codes64[7]) {
+			cbp++;
+		}
+        else if (codes64[8] | codes64[9] | codes64[10] | codes64[11]) {
+			cbp++;
+		}
+        else if (codes64[12] | codes64[13] | codes64[14] | codes64[15]) {
+			cbp++;
+		}
+		codes += 64;
+		i--;
+    } while (i != 0);
+
+	return cbp;
+}
+
+
+
+
+/* older code maybe better on some plattforms? */
+#if (0==1)
+	for (i = 5; i >= 0; i--) {
+		if (codes[1] | codes[2] | codes[3])
+                        cbp |= 1 << i;
+		else {
+			for (j = 4; j <= 56; j+=4) 	/* [60],[61],[62],[63] are last */
+				if (codes[j] | codes[j+1] | codes[j+2] | codes[j+3]) {
+				cbp |= 1 << i;
+				break;
+			}
+		}
+		codes += 64;
+	}
+
+	return cbp;
+#endif