root / ecc.h @ aa941b94
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/*
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* Calculate Error-correcting Codes. Used by NAND Flash controllers
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* (not by NAND chips).
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*
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* Copyright (c) 2006 Openedhand Ltd.
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* Written by Andrzej Zaborowski <balrog@zabor.org>
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*
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* This code is licensed under the GNU GPL v2.
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*/
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struct ecc_state_s {
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uint8_t cp; /* Column parity */
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uint16_t lp[2]; /* Line parity */ |
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uint16_t count; |
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}; |
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/*
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* Pre-calculated 256-way 1 byte column parity. Table borrowed from Linux.
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*/
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static const uint8_t nand_ecc_precalc_table[] = { |
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0x00, 0x55, 0x56, 0x03, 0x59, 0x0c, 0x0f, 0x5a, |
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0x5a, 0x0f, 0x0c, 0x59, 0x03, 0x56, 0x55, 0x00, |
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0x65, 0x30, 0x33, 0x66, 0x3c, 0x69, 0x6a, 0x3f, |
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0x3f, 0x6a, 0x69, 0x3c, 0x66, 0x33, 0x30, 0x65, |
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0x66, 0x33, 0x30, 0x65, 0x3f, 0x6a, 0x69, 0x3c, |
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0x3c, 0x69, 0x6a, 0x3f, 0x65, 0x30, 0x33, 0x66, |
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0x03, 0x56, 0x55, 0x00, 0x5a, 0x0f, 0x0c, 0x59, |
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0x59, 0x0c, 0x0f, 0x5a, 0x00, 0x55, 0x56, 0x03, |
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0x69, 0x3c, 0x3f, 0x6a, 0x30, 0x65, 0x66, 0x33, |
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0x33, 0x66, 0x65, 0x30, 0x6a, 0x3f, 0x3c, 0x69, |
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0x0c, 0x59, 0x5a, 0x0f, 0x55, 0x00, 0x03, 0x56, |
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0x56, 0x03, 0x00, 0x55, 0x0f, 0x5a, 0x59, 0x0c, |
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0x0f, 0x5a, 0x59, 0x0c, 0x56, 0x03, 0x00, 0x55, |
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0x55, 0x00, 0x03, 0x56, 0x0c, 0x59, 0x5a, 0x0f, |
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0x6a, 0x3f, 0x3c, 0x69, 0x33, 0x66, 0x65, 0x30, |
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0x30, 0x65, 0x66, 0x33, 0x69, 0x3c, 0x3f, 0x6a, |
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0x6a, 0x3f, 0x3c, 0x69, 0x33, 0x66, 0x65, 0x30, |
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0x30, 0x65, 0x66, 0x33, 0x69, 0x3c, 0x3f, 0x6a, |
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0x0f, 0x5a, 0x59, 0x0c, 0x56, 0x03, 0x00, 0x55, |
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0x55, 0x00, 0x03, 0x56, 0x0c, 0x59, 0x5a, 0x0f, |
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0x0c, 0x59, 0x5a, 0x0f, 0x55, 0x00, 0x03, 0x56, |
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0x56, 0x03, 0x00, 0x55, 0x0f, 0x5a, 0x59, 0x0c, |
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0x69, 0x3c, 0x3f, 0x6a, 0x30, 0x65, 0x66, 0x33, |
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0x33, 0x66, 0x65, 0x30, 0x6a, 0x3f, 0x3c, 0x69, |
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0x03, 0x56, 0x55, 0x00, 0x5a, 0x0f, 0x0c, 0x59, |
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0x59, 0x0c, 0x0f, 0x5a, 0x00, 0x55, 0x56, 0x03, |
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0x66, 0x33, 0x30, 0x65, 0x3f, 0x6a, 0x69, 0x3c, |
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0x3c, 0x69, 0x6a, 0x3f, 0x65, 0x30, 0x33, 0x66, |
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0x65, 0x30, 0x33, 0x66, 0x3c, 0x69, 0x6a, 0x3f, |
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0x3f, 0x6a, 0x69, 0x3c, 0x66, 0x33, 0x30, 0x65, |
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0x00, 0x55, 0x56, 0x03, 0x59, 0x0c, 0x0f, 0x5a, |
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0x5a, 0x0f, 0x0c, 0x59, 0x03, 0x56, 0x55, 0x00, |
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}; |
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/* Update ECC parity count. */
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static inline uint8_t ecc_digest(struct ecc_state_s *s, uint8_t sample) |
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{
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uint8_t idx = nand_ecc_precalc_table[sample]; |
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s->cp ^= idx & 0x3f;
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if (idx & 0x40) { |
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s->lp[0] ^= ~s->count;
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s->lp[1] ^= s->count;
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} |
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s->count ++; |
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return sample;
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} |
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/* Reinitialise the counters. */
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static inline void ecc_reset(struct ecc_state_s *s) |
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{
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s->lp[0] = 0x0000; |
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s->lp[1] = 0x0000; |
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s->cp = 0x00;
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s->count = 0;
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} |
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/* Save/restore */
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static inline void ecc_put(QEMUFile *f, struct ecc_state_s *s) |
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{
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qemu_put_8s(f, &s->cp); |
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qemu_put_be16s(f, &s->lp[0]);
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qemu_put_be16s(f, &s->lp[1]);
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qemu_put_be16s(f, &s->count); |
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} |
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static inline void ecc_get(QEMUFile *f, struct ecc_state_s *s) |
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{
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qemu_get_8s(f, &s->cp); |
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qemu_get_be16s(f, &s->lp[0]);
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qemu_get_be16s(f, &s->lp[1]);
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qemu_get_be16s(f, &s->count); |
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} |