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54 lines
1.3 KiB
54 lines
1.3 KiB
/* |
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* lib/reed_solomon/encode_rs.c |
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* |
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* Overview: |
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* Generic Reed Solomon encoder / decoder library |
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* |
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* Copyright 2002, Phil Karn, KA9Q |
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* May be used under the terms of the GNU General Public License (GPL) |
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* |
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* Adaption to the kernel by Thomas Gleixner (tglx@linutronix.de) |
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* |
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* $Id: encode_rs.c,v 1.5 2005/11/07 11:14:59 gleixner Exp $ |
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* |
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*/ |
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/* Generic data width independent code which is included by the |
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* wrappers. |
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* int encode_rsX (struct rs_control *rs, uintX_t *data, int len, uintY_t *par) |
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*/ |
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{ |
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int i, j, pad; |
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int nn = rs->nn; |
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int nroots = rs->nroots; |
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uint16_t *alpha_to = rs->alpha_to; |
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uint16_t *index_of = rs->index_of; |
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uint16_t *genpoly = rs->genpoly; |
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uint16_t fb; |
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uint16_t msk = (uint16_t) rs->nn; |
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/* Check length parameter for validity */ |
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pad = nn - nroots - len; |
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if (pad < 0 || pad >= nn) |
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return -ERANGE; |
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for (i = 0; i < len; i++) { |
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fb = index_of[((((uint16_t) data[i])^invmsk) & msk) ^ par[0]]; |
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/* feedback term is non-zero */ |
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if (fb != nn) { |
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for (j = 1; j < nroots; j++) { |
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par[j] ^= alpha_to[rs_modnn(rs, fb + |
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genpoly[nroots - j])]; |
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} |
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} |
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/* Shift */ |
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memmove(&par[0], &par[1], sizeof(uint16_t) * (nroots - 1)); |
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if (fb != nn) { |
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par[nroots - 1] = alpha_to[rs_modnn(rs, |
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fb + genpoly[0])]; |
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} else { |
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par[nroots - 1] = 0; |
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} |
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} |
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return 0; |
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}
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