X-Git-Url: http://www.aleph1.co.uk/gitweb/?p=yaffs%2F.git;a=blobdiff_plain;f=nand_ecc.c;fp=nand_ecc.c;h=0000000000000000000000000000000000000000;hp=c22397b801dce8fc41da5058dca77251357c46d2;hb=5b1ed5f8913d54fd9856d66421ae0f8e0b5769a9;hpb=b3c672d0ac3a2ef90d28f76c81f4eecbeb3b542f diff --git a/nand_ecc.c b/nand_ecc.c deleted file mode 100644 index c22397b..0000000 --- a/nand_ecc.c +++ /dev/null @@ -1,223 +0,0 @@ -/* - * drivers/mtd/nand_ecc.c - * - * Copyright (C) 2000 Steven J. Hill (sjhill@cotw.com) - * Toshiba America Electronics Components, Inc. - * - * $Id: nand_ecc.c,v 1.3 2002-09-27 20:50:50 charles Exp $ - * - * This program is free software; you can redistribute it and/or - * modify it under the terms of the GNU Lesser General Public License - * version 2.1 as published by the Free Software Foundation. - * - * This file contains an ECC algorithm from Toshiba that detects and - * corrects 1 bit errors in a 256 byte block of data. - */ - // Minor tweak by Charles Manning to prevent exporting symbols - // when compiled in with yaffs. - -const char *nand_ecc_c_version = "$Id: nand_ecc.c,v 1.3 2002-09-27 20:50:50 charles Exp $"; - -#if 0 -#include -#include -#include -#endif - -#include "yportenv.h" - -/* - * Pre-calculated 256-way 1 byte column parity - */ -static const u_char nand_ecc_precalc_table[] = { - 0x00, 0x55, 0x56, 0x03, 0x59, 0x0c, 0x0f, 0x5a, 0x5a, 0x0f, 0x0c, 0x59, 0x03, 0x56, 0x55, 0x00, - 0x65, 0x30, 0x33, 0x66, 0x3c, 0x69, 0x6a, 0x3f, 0x3f, 0x6a, 0x69, 0x3c, 0x66, 0x33, 0x30, 0x65, - 0x66, 0x33, 0x30, 0x65, 0x3f, 0x6a, 0x69, 0x3c, 0x3c, 0x69, 0x6a, 0x3f, 0x65, 0x30, 0x33, 0x66, - 0x03, 0x56, 0x55, 0x00, 0x5a, 0x0f, 0x0c, 0x59, 0x59, 0x0c, 0x0f, 0x5a, 0x00, 0x55, 0x56, 0x03, - 0x69, 0x3c, 0x3f, 0x6a, 0x30, 0x65, 0x66, 0x33, 0x33, 0x66, 0x65, 0x30, 0x6a, 0x3f, 0x3c, 0x69, - 0x0c, 0x59, 0x5a, 0x0f, 0x55, 0x00, 0x03, 0x56, 0x56, 0x03, 0x00, 0x55, 0x0f, 0x5a, 0x59, 0x0c, - 0x0f, 0x5a, 0x59, 0x0c, 0x56, 0x03, 0x00, 0x55, 0x55, 0x00, 0x03, 0x56, 0x0c, 0x59, 0x5a, 0x0f, - 0x6a, 0x3f, 0x3c, 0x69, 0x33, 0x66, 0x65, 0x30, 0x30, 0x65, 0x66, 0x33, 0x69, 0x3c, 0x3f, 0x6a, - 0x6a, 0x3f, 0x3c, 0x69, 0x33, 0x66, 0x65, 0x30, 0x30, 0x65, 0x66, 0x33, 0x69, 0x3c, 0x3f, 0x6a, - 0x0f, 0x5a, 0x59, 0x0c, 0x56, 0x03, 0x00, 0x55, 0x55, 0x00, 0x03, 0x56, 0x0c, 0x59, 0x5a, 0x0f, - 0x0c, 0x59, 0x5a, 0x0f, 0x55, 0x00, 0x03, 0x56, 0x56, 0x03, 0x00, 0x55, 0x0f, 0x5a, 0x59, 0x0c, - 0x69, 0x3c, 0x3f, 0x6a, 0x30, 0x65, 0x66, 0x33, 0x33, 0x66, 0x65, 0x30, 0x6a, 0x3f, 0x3c, 0x69, - 0x03, 0x56, 0x55, 0x00, 0x5a, 0x0f, 0x0c, 0x59, 0x59, 0x0c, 0x0f, 0x5a, 0x00, 0x55, 0x56, 0x03, - 0x66, 0x33, 0x30, 0x65, 0x3f, 0x6a, 0x69, 0x3c, 0x3c, 0x69, 0x6a, 0x3f, 0x65, 0x30, 0x33, 0x66, - 0x65, 0x30, 0x33, 0x66, 0x3c, 0x69, 0x6a, 0x3f, 0x3f, 0x6a, 0x69, 0x3c, 0x66, 0x33, 0x30, 0x65, - 0x00, 0x55, 0x56, 0x03, 0x59, 0x0c, 0x0f, 0x5a, 0x5a, 0x0f, 0x0c, 0x59, 0x03, 0x56, 0x55, 0x00 -}; - - -/* - * Creates non-inverted ECC code from line parity - */ -static void nand_trans_result(u_char reg2, u_char reg3, - u_char *ecc_code) -{ - u_char a, b, i, tmp1, tmp2; - - /* Initialize variables */ - a = b = 0x80; - tmp1 = tmp2 = 0; - - /* Calculate first ECC byte */ - for (i = 0; i < 4; i++) { - if (reg3 & a) /* LP15,13,11,9 --> ecc_code[0] */ - tmp1 |= b; - b >>= 1; - if (reg2 & a) /* LP14,12,10,8 --> ecc_code[0] */ - tmp1 |= b; - b >>= 1; - a >>= 1; - } - - /* Calculate second ECC byte */ - b = 0x80; - for (i = 0; i < 4; i++) { - if (reg3 & a) /* LP7,5,3,1 --> ecc_code[1] */ - tmp2 |= b; - b >>= 1; - if (reg2 & a) /* LP6,4,2,0 --> ecc_code[1] */ - tmp2 |= b; - b >>= 1; - a >>= 1; - } - - /* Store two of the ECC bytes */ - ecc_code[0] = tmp1; - ecc_code[1] = tmp2; -} - -/* - * Calculate 3 byte ECC code for 256 byte block - */ -void nand_calculate_ecc (const u_char *dat, u_char *ecc_code) -{ - u_char idx, reg1, reg2, reg3; - int j; - - /* Initialize variables */ - reg1 = reg2 = reg3 = 0; - ecc_code[0] = ecc_code[1] = ecc_code[2] = 0; - - /* Build up column parity */ - for(j = 0; j < 256; j++) { - - /* Get CP0 - CP5 from table */ - idx = nand_ecc_precalc_table[dat[j]]; - reg1 ^= (idx & 0x3f); - - /* All bit XOR = 1 ? */ - if (idx & 0x40) { - reg3 ^= (u_char) j; - reg2 ^= ~((u_char) j); - } - } - - /* Create non-inverted ECC code from line parity */ - nand_trans_result(reg2, reg3, ecc_code); - - /* Calculate final ECC code */ - ecc_code[0] = ~ecc_code[0]; - ecc_code[1] = ~ecc_code[1]; - ecc_code[2] = ((~reg1) << 2) | 0x03; -} - -/* - * Detect and correct a 1 bit error for 256 byte block - */ -int nand_correct_data (u_char *dat, u_char *read_ecc, u_char *calc_ecc) -{ - u_char a, b, c, d1, d2, d3, add, bit, i; - - /* Do error detection */ - d1 = calc_ecc[0] ^ read_ecc[0]; - d2 = calc_ecc[1] ^ read_ecc[1]; - d3 = calc_ecc[2] ^ read_ecc[2]; - - if ((d1 | d2 | d3) == 0) { - /* No errors */ - return 0; - } - else { - a = (d1 ^ (d1 >> 1)) & 0x55; - b = (d2 ^ (d2 >> 1)) & 0x55; - c = (d3 ^ (d3 >> 1)) & 0x54; - - /* Found and will correct single bit error in the data */ - if ((a == 0x55) && (b == 0x55) && (c == 0x54)) { - c = 0x80; - add = 0; - a = 0x80; - for (i=0; i<4; i++) { - if (d1 & c) - add |= a; - c >>= 2; - a >>= 1; - } - c = 0x80; - for (i=0; i<4; i++) { - if (d2 & c) - add |= a; - c >>= 2; - a >>= 1; - } - bit = 0; - b = 0x04; - c = 0x80; - for (i=0; i<3; i++) { - if (d3 & c) - bit |= b; - c >>= 2; - b >>= 1; - } - b = 0x01; - a = dat[add]; - a ^= (b << bit); - dat[add] = a; - return 1; - } - else { - i = 0; - while (d1) { - if (d1 & 0x01) - ++i; - d1 >>= 1; - } - while (d2) { - if (d2 & 0x01) - ++i; - d2 >>= 1; - } - while (d3) { - if (d3 & 0x01) - ++i; - d3 >>= 1; - } - if (i == 1) { - /* ECC Code Error Correction */ - read_ecc[0] = calc_ecc[0]; - read_ecc[1] = calc_ecc[1]; - read_ecc[2] = calc_ecc[2]; - return 2; - } - else { - /* Uncorrectable Error */ - return -1; - } - } - } - - /* Should never happen */ - return -1; -} - -#if 0 -EXPORT_SYMBOL(nand_calculate_ecc); -EXPORT_SYMBOL(nand_correct_data); - -MODULE_LICENSE("GPL"); -MODULE_AUTHOR("Steven J. Hill "); -MODULE_DESCRIPTION("Generic NAND ECC support"); -#endif