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Diffstat (limited to 'ubi-utils/src/nandecc.c')
| -rw-r--r-- | ubi-utils/src/nandecc.c | 159 |
1 files changed, 159 insertions, 0 deletions
diff --git a/ubi-utils/src/nandecc.c b/ubi-utils/src/nandecc.c new file mode 100644 index 0000000..71660ef --- /dev/null +++ b/ubi-utils/src/nandecc.c @@ -0,0 +1,159 @@ +/* + * This file contains an ECC algorithm from Toshiba that detects and + * corrects 1 bit errors in a 256 byte block of data. + * + * drivers/mtd/nand/nand_ecc.c + * + * Copyright (C) 2000-2004 Steven J. Hill (sjhill@realitydiluted.com) + * Toshiba America Electronics Components, Inc. + * + * This file is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License as published by the + * Free Software Foundation; either version 2 or (at your option) any + * later version. + * + * This file is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * for more details. + * + * You should have received a copy of the GNU General Public License along + * with this file; if not, write to the Free Software Foundation, Inc., + * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. + * + * As a special exception, if other files instantiate templates or use + * macros or inline functions from these files, or you compile these + * files and link them with other works to produce a work based on these + * files, these files do not by themselves cause the resulting work to be + * covered by the GNU General Public License. However the source code for + * these files must still be made available in accordance with section (3) + * of the GNU General Public License. + * + * This exception does not invalidate any other reasons why a work based on + * this file might be covered by the GNU General Public License. + */ + +#include "nandecc.h" + +/* + * Pre-calculated 256-way 1 byte column parity + */ +static const uint8_t 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 +}; + +/** + * nand_trans_result - [GENERIC] create non-inverted ECC + * @reg2: line parity reg 2 + * @reg3: line parity reg 3 + * @ecc_code: ecc + * + * Creates non-inverted ECC code from line parity + */ +static void nand_trans_result(uint8_t reg2, uint8_t reg3, + uint8_t *ecc_code) +{ + uint8_t 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[1] = tmp1; + ecc_code[0] = tmp2; +} + +/** + * nand_calculate_ecc - [NAND Interface] Calculate 3 byte ECC code for + * 256 byte block + * + * @dat: raw data + * @ecc_code: buffer for ECC + */ +int nand_calculate_ecc(const uint8_t *dat, uint8_t *ecc_code) +{ + uint8_t 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 ^= (uint8_t) j; + reg2 ^= ~((uint8_t) 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; + return 0; +} |