Marginally faster nand_ecc.c

Marginally faster nand_ecc.c

[Charles Manning]

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Folks

Herewith a patch that speeds up nand_ecc.c slightly. This should speed it up 
to be the same as yaffs_ecc.c which runs approx 15% faster than regular 
nand_ecc.c in the tests I have done.

All we're doing is moving the masking to outside the loop so we only take the 
hit once.

-- CHarles



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--- nand_ecc.c.orig	2006-09-23 09:51:09.000000000 +1200
+++ nand_ecc.c	2006-09-23 09:52:12.000000000 +1200
@@ -128,7 +128,7 @@
 
 		/* Get CP0 - CP5 from table */
 		idx = nand_ecc_precalc_table[dat[j]];
-		reg1 ^= (idx & 0x3f);
+		reg1 ^= idx;
 
 		/* All bit XOR = 1 ? */
 		if (idx & 0x40) {
@@ -136,6 +136,8 @@
 			reg2 ^= ~((u_char) j);
 		}
 	}
+	
+	reg1 &= 0x3f;
 
 	/* Create non-inverted ECC code from line parity */
 	nand_trans_result(reg2, reg3, ecc_code);