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309600c14e
Currently, the selection of ECC byte ordering for software hamming is done at compilation time, which doesn't make sense when ECC byte calculation is done in hardware and byte ordering is forced by the hardware engine. In this case, only the correction is done in software and we want to force the byte-ordering no matter the value of CONFIG_MTD_NAND_ECC_SMC. This is typically the case for the FSMC (Smart Media ordering), TMIO and TXX9NDFMC (regular byte ordering) blocks. For all other use cases (pure software implementation, SM FTL and nandecctest), we keep selecting the byte ordering based on the CONFIG_MTD_NAND_ECC_SMC value. It might not be ideal for SM FTL (I'd expect Smart Media ordering to be employed by the Smart Media FTL), but this option doesn't seem to be enabled in the existing _defconfig, so I can't tell setting sm_order to true is the right choice. Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
499 lines
15 KiB
C
499 lines
15 KiB
C
/*
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* This file contains an ECC algorithm that detects and corrects 1 bit
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* errors in a 256 byte block of data.
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*
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* Copyright © 2008 Koninklijke Philips Electronics NV.
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* Author: Frans Meulenbroeks
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*
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* Completely replaces the previous ECC implementation which was written by:
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* Steven J. Hill (sjhill@realitydiluted.com)
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* Thomas Gleixner (tglx@linutronix.de)
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*
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* Information on how this algorithm works and how it was developed
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* can be found in Documentation/mtd/nand_ecc.txt
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*
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* This file is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 or (at your option) any
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* later version.
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*
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* This file is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this file; if not, write to the Free Software Foundation, Inc.,
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* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
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*
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*/
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#include <linux/types.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/mtd/mtd.h>
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#include <linux/mtd/rawnand.h>
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#include <linux/mtd/nand_ecc.h>
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#include <asm/byteorder.h>
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/*
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* invparity is a 256 byte table that contains the odd parity
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* for each byte. So if the number of bits in a byte is even,
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* the array element is 1, and when the number of bits is odd
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* the array eleemnt is 0.
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*/
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static const char invparity[256] = {
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1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
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0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
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0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
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1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
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0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
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1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
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1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
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0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
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0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
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1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
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1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
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0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
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1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1,
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0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
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0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0,
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1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 0, 1
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};
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/*
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* bitsperbyte contains the number of bits per byte
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* this is only used for testing and repairing parity
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* (a precalculated value slightly improves performance)
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*/
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static const char bitsperbyte[256] = {
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0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4,
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1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
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1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
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2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
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1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
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2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
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2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
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3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
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1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
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2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
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2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
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3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
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2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
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3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
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3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
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4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8,
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};
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/*
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* addressbits is a lookup table to filter out the bits from the xor-ed
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* ECC data that identify the faulty location.
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* this is only used for repairing parity
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* see the comments in nand_correct_data for more details
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*/
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static const char addressbits[256] = {
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0x00, 0x00, 0x01, 0x01, 0x00, 0x00, 0x01, 0x01,
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0x02, 0x02, 0x03, 0x03, 0x02, 0x02, 0x03, 0x03,
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0x00, 0x00, 0x01, 0x01, 0x00, 0x00, 0x01, 0x01,
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0x02, 0x02, 0x03, 0x03, 0x02, 0x02, 0x03, 0x03,
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0x04, 0x04, 0x05, 0x05, 0x04, 0x04, 0x05, 0x05,
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0x06, 0x06, 0x07, 0x07, 0x06, 0x06, 0x07, 0x07,
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0x04, 0x04, 0x05, 0x05, 0x04, 0x04, 0x05, 0x05,
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0x06, 0x06, 0x07, 0x07, 0x06, 0x06, 0x07, 0x07,
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0x00, 0x00, 0x01, 0x01, 0x00, 0x00, 0x01, 0x01,
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0x02, 0x02, 0x03, 0x03, 0x02, 0x02, 0x03, 0x03,
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0x00, 0x00, 0x01, 0x01, 0x00, 0x00, 0x01, 0x01,
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0x02, 0x02, 0x03, 0x03, 0x02, 0x02, 0x03, 0x03,
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0x04, 0x04, 0x05, 0x05, 0x04, 0x04, 0x05, 0x05,
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0x06, 0x06, 0x07, 0x07, 0x06, 0x06, 0x07, 0x07,
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0x04, 0x04, 0x05, 0x05, 0x04, 0x04, 0x05, 0x05,
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0x06, 0x06, 0x07, 0x07, 0x06, 0x06, 0x07, 0x07,
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0x08, 0x08, 0x09, 0x09, 0x08, 0x08, 0x09, 0x09,
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0x0a, 0x0a, 0x0b, 0x0b, 0x0a, 0x0a, 0x0b, 0x0b,
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0x08, 0x08, 0x09, 0x09, 0x08, 0x08, 0x09, 0x09,
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0x0a, 0x0a, 0x0b, 0x0b, 0x0a, 0x0a, 0x0b, 0x0b,
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0x0c, 0x0c, 0x0d, 0x0d, 0x0c, 0x0c, 0x0d, 0x0d,
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0x0e, 0x0e, 0x0f, 0x0f, 0x0e, 0x0e, 0x0f, 0x0f,
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0x0c, 0x0c, 0x0d, 0x0d, 0x0c, 0x0c, 0x0d, 0x0d,
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0x0e, 0x0e, 0x0f, 0x0f, 0x0e, 0x0e, 0x0f, 0x0f,
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0x08, 0x08, 0x09, 0x09, 0x08, 0x08, 0x09, 0x09,
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0x0a, 0x0a, 0x0b, 0x0b, 0x0a, 0x0a, 0x0b, 0x0b,
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0x08, 0x08, 0x09, 0x09, 0x08, 0x08, 0x09, 0x09,
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0x0a, 0x0a, 0x0b, 0x0b, 0x0a, 0x0a, 0x0b, 0x0b,
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0x0c, 0x0c, 0x0d, 0x0d, 0x0c, 0x0c, 0x0d, 0x0d,
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0x0e, 0x0e, 0x0f, 0x0f, 0x0e, 0x0e, 0x0f, 0x0f,
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0x0c, 0x0c, 0x0d, 0x0d, 0x0c, 0x0c, 0x0d, 0x0d,
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0x0e, 0x0e, 0x0f, 0x0f, 0x0e, 0x0e, 0x0f, 0x0f
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};
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/**
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* __nand_calculate_ecc - [NAND Interface] Calculate 3-byte ECC for 256/512-byte
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* block
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* @buf: input buffer with raw data
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* @eccsize: data bytes per ECC step (256 or 512)
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* @code: output buffer with ECC
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* @sm_order: Smart Media byte ordering
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*/
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void __nand_calculate_ecc(const unsigned char *buf, unsigned int eccsize,
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unsigned char *code, bool sm_order)
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{
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int i;
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const uint32_t *bp = (uint32_t *)buf;
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/* 256 or 512 bytes/ecc */
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const uint32_t eccsize_mult = eccsize >> 8;
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uint32_t cur; /* current value in buffer */
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/* rp0..rp15..rp17 are the various accumulated parities (per byte) */
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uint32_t rp0, rp1, rp2, rp3, rp4, rp5, rp6, rp7;
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uint32_t rp8, rp9, rp10, rp11, rp12, rp13, rp14, rp15, rp16;
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uint32_t uninitialized_var(rp17); /* to make compiler happy */
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uint32_t par; /* the cumulative parity for all data */
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uint32_t tmppar; /* the cumulative parity for this iteration;
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for rp12, rp14 and rp16 at the end of the
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loop */
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par = 0;
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rp4 = 0;
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rp6 = 0;
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rp8 = 0;
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rp10 = 0;
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rp12 = 0;
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rp14 = 0;
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rp16 = 0;
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/*
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* The loop is unrolled a number of times;
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* This avoids if statements to decide on which rp value to update
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* Also we process the data by longwords.
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* Note: passing unaligned data might give a performance penalty.
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* It is assumed that the buffers are aligned.
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* tmppar is the cumulative sum of this iteration.
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* needed for calculating rp12, rp14, rp16 and par
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* also used as a performance improvement for rp6, rp8 and rp10
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*/
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for (i = 0; i < eccsize_mult << 2; i++) {
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cur = *bp++;
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tmppar = cur;
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rp4 ^= cur;
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cur = *bp++;
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tmppar ^= cur;
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rp6 ^= tmppar;
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cur = *bp++;
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tmppar ^= cur;
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rp4 ^= cur;
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cur = *bp++;
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tmppar ^= cur;
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rp8 ^= tmppar;
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cur = *bp++;
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tmppar ^= cur;
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rp4 ^= cur;
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rp6 ^= cur;
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cur = *bp++;
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tmppar ^= cur;
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rp6 ^= cur;
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cur = *bp++;
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tmppar ^= cur;
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rp4 ^= cur;
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cur = *bp++;
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tmppar ^= cur;
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rp10 ^= tmppar;
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cur = *bp++;
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tmppar ^= cur;
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rp4 ^= cur;
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rp6 ^= cur;
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rp8 ^= cur;
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cur = *bp++;
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tmppar ^= cur;
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rp6 ^= cur;
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rp8 ^= cur;
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cur = *bp++;
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tmppar ^= cur;
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rp4 ^= cur;
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rp8 ^= cur;
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cur = *bp++;
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tmppar ^= cur;
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rp8 ^= cur;
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cur = *bp++;
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tmppar ^= cur;
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rp4 ^= cur;
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rp6 ^= cur;
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cur = *bp++;
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tmppar ^= cur;
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rp6 ^= cur;
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cur = *bp++;
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tmppar ^= cur;
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rp4 ^= cur;
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cur = *bp++;
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tmppar ^= cur;
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par ^= tmppar;
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if ((i & 0x1) == 0)
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rp12 ^= tmppar;
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if ((i & 0x2) == 0)
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rp14 ^= tmppar;
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if (eccsize_mult == 2 && (i & 0x4) == 0)
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rp16 ^= tmppar;
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}
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/*
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* handle the fact that we use longword operations
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* we'll bring rp4..rp14..rp16 back to single byte entities by
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* shifting and xoring first fold the upper and lower 16 bits,
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* then the upper and lower 8 bits.
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*/
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rp4 ^= (rp4 >> 16);
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rp4 ^= (rp4 >> 8);
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rp4 &= 0xff;
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rp6 ^= (rp6 >> 16);
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rp6 ^= (rp6 >> 8);
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rp6 &= 0xff;
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rp8 ^= (rp8 >> 16);
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rp8 ^= (rp8 >> 8);
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rp8 &= 0xff;
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rp10 ^= (rp10 >> 16);
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rp10 ^= (rp10 >> 8);
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rp10 &= 0xff;
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rp12 ^= (rp12 >> 16);
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rp12 ^= (rp12 >> 8);
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rp12 &= 0xff;
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rp14 ^= (rp14 >> 16);
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rp14 ^= (rp14 >> 8);
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rp14 &= 0xff;
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if (eccsize_mult == 2) {
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rp16 ^= (rp16 >> 16);
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rp16 ^= (rp16 >> 8);
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rp16 &= 0xff;
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}
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/*
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* we also need to calculate the row parity for rp0..rp3
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* This is present in par, because par is now
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* rp3 rp3 rp2 rp2 in little endian and
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* rp2 rp2 rp3 rp3 in big endian
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* as well as
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* rp1 rp0 rp1 rp0 in little endian and
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* rp0 rp1 rp0 rp1 in big endian
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* First calculate rp2 and rp3
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*/
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#ifdef __BIG_ENDIAN
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rp2 = (par >> 16);
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rp2 ^= (rp2 >> 8);
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rp2 &= 0xff;
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rp3 = par & 0xffff;
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rp3 ^= (rp3 >> 8);
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rp3 &= 0xff;
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#else
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rp3 = (par >> 16);
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rp3 ^= (rp3 >> 8);
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rp3 &= 0xff;
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rp2 = par & 0xffff;
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rp2 ^= (rp2 >> 8);
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rp2 &= 0xff;
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#endif
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/* reduce par to 16 bits then calculate rp1 and rp0 */
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par ^= (par >> 16);
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#ifdef __BIG_ENDIAN
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rp0 = (par >> 8) & 0xff;
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rp1 = (par & 0xff);
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#else
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rp1 = (par >> 8) & 0xff;
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rp0 = (par & 0xff);
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#endif
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/* finally reduce par to 8 bits */
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par ^= (par >> 8);
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par &= 0xff;
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/*
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* and calculate rp5..rp15..rp17
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* note that par = rp4 ^ rp5 and due to the commutative property
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* of the ^ operator we can say:
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* rp5 = (par ^ rp4);
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* The & 0xff seems superfluous, but benchmarking learned that
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* leaving it out gives slightly worse results. No idea why, probably
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* it has to do with the way the pipeline in pentium is organized.
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*/
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rp5 = (par ^ rp4) & 0xff;
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rp7 = (par ^ rp6) & 0xff;
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rp9 = (par ^ rp8) & 0xff;
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rp11 = (par ^ rp10) & 0xff;
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rp13 = (par ^ rp12) & 0xff;
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rp15 = (par ^ rp14) & 0xff;
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if (eccsize_mult == 2)
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rp17 = (par ^ rp16) & 0xff;
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/*
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* Finally calculate the ECC bits.
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* Again here it might seem that there are performance optimisations
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* possible, but benchmarks showed that on the system this is developed
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* the code below is the fastest
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*/
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if (sm_order) {
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code[0] = (invparity[rp7] << 7) | (invparity[rp6] << 6) |
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(invparity[rp5] << 5) | (invparity[rp4] << 4) |
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(invparity[rp3] << 3) | (invparity[rp2] << 2) |
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(invparity[rp1] << 1) | (invparity[rp0]);
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code[1] = (invparity[rp15] << 7) | (invparity[rp14] << 6) |
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(invparity[rp13] << 5) | (invparity[rp12] << 4) |
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(invparity[rp11] << 3) | (invparity[rp10] << 2) |
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(invparity[rp9] << 1) | (invparity[rp8]);
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} else {
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code[1] = (invparity[rp7] << 7) | (invparity[rp6] << 6) |
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(invparity[rp5] << 5) | (invparity[rp4] << 4) |
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(invparity[rp3] << 3) | (invparity[rp2] << 2) |
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(invparity[rp1] << 1) | (invparity[rp0]);
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code[0] = (invparity[rp15] << 7) | (invparity[rp14] << 6) |
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(invparity[rp13] << 5) | (invparity[rp12] << 4) |
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(invparity[rp11] << 3) | (invparity[rp10] << 2) |
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(invparity[rp9] << 1) | (invparity[rp8]);
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}
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if (eccsize_mult == 1)
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code[2] =
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(invparity[par & 0xf0] << 7) |
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(invparity[par & 0x0f] << 6) |
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(invparity[par & 0xcc] << 5) |
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(invparity[par & 0x33] << 4) |
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(invparity[par & 0xaa] << 3) |
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(invparity[par & 0x55] << 2) |
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3;
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else
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code[2] =
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(invparity[par & 0xf0] << 7) |
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(invparity[par & 0x0f] << 6) |
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(invparity[par & 0xcc] << 5) |
|
|
(invparity[par & 0x33] << 4) |
|
|
(invparity[par & 0xaa] << 3) |
|
|
(invparity[par & 0x55] << 2) |
|
|
(invparity[rp17] << 1) |
|
|
(invparity[rp16] << 0);
|
|
}
|
|
EXPORT_SYMBOL(__nand_calculate_ecc);
|
|
|
|
/**
|
|
* nand_calculate_ecc - [NAND Interface] Calculate 3-byte ECC for 256/512-byte
|
|
* block
|
|
* @chip: NAND chip object
|
|
* @buf: input buffer with raw data
|
|
* @code: output buffer with ECC
|
|
*/
|
|
int nand_calculate_ecc(struct nand_chip *chip, const unsigned char *buf,
|
|
unsigned char *code)
|
|
{
|
|
bool sm_order = chip->ecc.options & NAND_ECC_SOFT_HAMMING_SM_ORDER;
|
|
|
|
__nand_calculate_ecc(buf, chip->ecc.size, code, sm_order);
|
|
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(nand_calculate_ecc);
|
|
|
|
/**
|
|
* __nand_correct_data - [NAND Interface] Detect and correct bit error(s)
|
|
* @buf: raw data read from the chip
|
|
* @read_ecc: ECC from the chip
|
|
* @calc_ecc: the ECC calculated from raw data
|
|
* @eccsize: data bytes per ECC step (256 or 512)
|
|
* @sm_order: Smart Media byte order
|
|
*
|
|
* Detect and correct a 1 bit error for eccsize byte block
|
|
*/
|
|
int __nand_correct_data(unsigned char *buf,
|
|
unsigned char *read_ecc, unsigned char *calc_ecc,
|
|
unsigned int eccsize, bool sm_order)
|
|
{
|
|
unsigned char b0, b1, b2, bit_addr;
|
|
unsigned int byte_addr;
|
|
/* 256 or 512 bytes/ecc */
|
|
const uint32_t eccsize_mult = eccsize >> 8;
|
|
|
|
/*
|
|
* b0 to b2 indicate which bit is faulty (if any)
|
|
* we might need the xor result more than once,
|
|
* so keep them in a local var
|
|
*/
|
|
if (sm_order) {
|
|
b0 = read_ecc[0] ^ calc_ecc[0];
|
|
b1 = read_ecc[1] ^ calc_ecc[1];
|
|
} else {
|
|
b0 = read_ecc[1] ^ calc_ecc[1];
|
|
b1 = read_ecc[0] ^ calc_ecc[0];
|
|
}
|
|
|
|
b2 = read_ecc[2] ^ calc_ecc[2];
|
|
|
|
/* check if there are any bitfaults */
|
|
|
|
/* repeated if statements are slightly more efficient than switch ... */
|
|
/* ordered in order of likelihood */
|
|
|
|
if ((b0 | b1 | b2) == 0)
|
|
return 0; /* no error */
|
|
|
|
if ((((b0 ^ (b0 >> 1)) & 0x55) == 0x55) &&
|
|
(((b1 ^ (b1 >> 1)) & 0x55) == 0x55) &&
|
|
((eccsize_mult == 1 && ((b2 ^ (b2 >> 1)) & 0x54) == 0x54) ||
|
|
(eccsize_mult == 2 && ((b2 ^ (b2 >> 1)) & 0x55) == 0x55))) {
|
|
/* single bit error */
|
|
/*
|
|
* rp17/rp15/13/11/9/7/5/3/1 indicate which byte is the faulty
|
|
* byte, cp 5/3/1 indicate the faulty bit.
|
|
* A lookup table (called addressbits) is used to filter
|
|
* the bits from the byte they are in.
|
|
* A marginal optimisation is possible by having three
|
|
* different lookup tables.
|
|
* One as we have now (for b0), one for b2
|
|
* (that would avoid the >> 1), and one for b1 (with all values
|
|
* << 4). However it was felt that introducing two more tables
|
|
* hardly justify the gain.
|
|
*
|
|
* The b2 shift is there to get rid of the lowest two bits.
|
|
* We could also do addressbits[b2] >> 1 but for the
|
|
* performance it does not make any difference
|
|
*/
|
|
if (eccsize_mult == 1)
|
|
byte_addr = (addressbits[b1] << 4) + addressbits[b0];
|
|
else
|
|
byte_addr = (addressbits[b2 & 0x3] << 8) +
|
|
(addressbits[b1] << 4) + addressbits[b0];
|
|
bit_addr = addressbits[b2 >> 2];
|
|
/* flip the bit */
|
|
buf[byte_addr] ^= (1 << bit_addr);
|
|
return 1;
|
|
|
|
}
|
|
/* count nr of bits; use table lookup, faster than calculating it */
|
|
if ((bitsperbyte[b0] + bitsperbyte[b1] + bitsperbyte[b2]) == 1)
|
|
return 1; /* error in ECC data; no action needed */
|
|
|
|
pr_err("%s: uncorrectable ECC error\n", __func__);
|
|
return -EBADMSG;
|
|
}
|
|
EXPORT_SYMBOL(__nand_correct_data);
|
|
|
|
/**
|
|
* nand_correct_data - [NAND Interface] Detect and correct bit error(s)
|
|
* @chip: NAND chip object
|
|
* @buf: raw data read from the chip
|
|
* @read_ecc: ECC from the chip
|
|
* @calc_ecc: the ECC calculated from raw data
|
|
*
|
|
* Detect and correct a 1 bit error for 256/512 byte block
|
|
*/
|
|
int nand_correct_data(struct nand_chip *chip, unsigned char *buf,
|
|
unsigned char *read_ecc, unsigned char *calc_ecc)
|
|
{
|
|
bool sm_order = chip->ecc.options & NAND_ECC_SOFT_HAMMING_SM_ORDER;
|
|
|
|
return __nand_correct_data(buf, read_ecc, calc_ecc, chip->ecc.size,
|
|
sm_order);
|
|
}
|
|
EXPORT_SYMBOL(nand_correct_data);
|
|
|
|
MODULE_LICENSE("GPL");
|
|
MODULE_AUTHOR("Frans Meulenbroeks <fransmeulenbroeks@gmail.com>");
|
|
MODULE_DESCRIPTION("Generic NAND ECC support");
|