From 8bde7f776c77b343aca29b8c7b58464d915ac245 Mon Sep 17 00:00:00 2001 From: wdenk Date: Fri, 27 Jun 2003 21:31:46 +0000 Subject: * Code cleanup: - remove trailing white space, trailing empty lines, C++ comments, etc. - split cmd_boot.c (separate cmd_bdinfo.c and cmd_load.c) * Patches by Kenneth Johansson, 25 Jun 2003: - major rework of command structure (work done mostly by Michal Cendrowski and Joakim Kristiansen) --- common/docecc.c | 100 ++++++++++++++++++++++++++++---------------------------- 1 file changed, 50 insertions(+), 50 deletions(-) (limited to 'common/docecc.c') diff --git a/common/docecc.c b/common/docecc.c index 74ac7411a4..cf45e0f6d9 100644 --- a/common/docecc.c +++ b/common/docecc.c @@ -98,30 +98,30 @@ for(ci=(n)-1;ci >=0;ci--)\ /* generate GF(2**m) from the irreducible polynomial p(X) in Pp[0]..Pp[m] lookup tables: index->polynomial form alpha_to[] contains j=alpha**i; - polynomial form -> index form index_of[j=alpha**i] = i + polynomial form -> index form index_of[j=alpha**i] = i alpha=2 is the primitive element of GF(2**m) HARI's COMMENT: (4/13/94) alpha_to[] can be used as follows: - Let @ represent the primitive element commonly called "alpha" that + Let @ represent the primitive element commonly called "alpha" that is the root of the primitive polynomial p(x). Then in GF(2^m), for any 0 <= i <= 2^m-2, - @^i = a(0) + a(1) @ + a(2) @^2 + ... + a(m-1) @^(m-1) + @^i = a(0) + a(1) @ + a(2) @^2 + ... + a(m-1) @^(m-1) where the binary vector (a(0),a(1),a(2),...,a(m-1)) is the representation of the integer "alpha_to[i]" with a(0) being the LSB and a(m-1) the MSB. Thus for example the polynomial representation of @^5 would be given by the binary representation of the integer "alpha_to[5]". - Similarily, index_of[] can be used as follows: - As above, let @ represent the primitive element of GF(2^m) that is + Similarily, index_of[] can be used as follows: + As above, let @ represent the primitive element of GF(2^m) that is the root of the primitive polynomial p(x). In order to find the power of @ (alpha) that has the polynomial representation - a(0) + a(1) @ + a(2) @^2 + ... + a(m-1) @^(m-1) + a(0) + a(1) @ + a(2) @^2 + ... + a(m-1) @^(m-1) we consider the integer "i" whose binary representation with a(0) being LSB and a(m-1) MSB is (a(0),a(1),...,a(m-1)) and locate the entry "index_of[i]". Now, @^index_of[i] is that element whose polynomial representation is (a(0),a(1),a(2),...,a(m-1)). NOTE: - The element alpha_to[2^m-1] = 0 always signifying that the + The element alpha_to[2^m-1] = 0 always signifying that the representation of "@^infinity" = 0 is (0,0,0,...,0). - Similarily, the element index_of[0] = A0 always signifying + Similarily, the element index_of[0] = A0 always signifying that the power of alpha which has the polynomial representation (0,0,...,0) is "infinity". @@ -183,8 +183,8 @@ generate_gf(dtype Alpha_to[NN + 1], dtype Index_of[NN + 1]) * */ static int eras_dec_rs(dtype Alpha_to[NN + 1], dtype Index_of[NN + 1], - gf bb[NN - KK + 1], gf eras_val[NN-KK], int eras_pos[NN-KK], - int no_eras) + gf bb[NN - KK + 1], gf eras_val[NN-KK], int eras_pos[NN-KK], + int no_eras) { int deg_lambda, el, deg_omega; int i, j, r,k; @@ -225,7 +225,7 @@ eras_dec_rs(dtype Alpha_to[NN + 1], dtype Index_of[NN + 1], for(i=1;i<=NN-KK;i++) { tmp = Index_of[s[i]]; if (tmp != A0) - tmp = modnn(tmp + 2 * KK * (B0+i-1)*PRIM); + tmp = modnn(tmp + 2 * KK * (B0+i-1)*PRIM); s[i] = tmp; } @@ -412,9 +412,9 @@ eras_dec_rs(dtype Alpha_to[NN + 1], dtype Index_of[NN + 1], } /* Apply error to data */ if (num1 != 0) { - eras_val[j] = Alpha_to[modnn(Index_of[num1] + Index_of[num2] + NN - Index_of[den])]; + eras_val[j] = Alpha_to[modnn(Index_of[num1] + Index_of[num2] + NN - Index_of[den])]; } else { - eras_val[j] = 0; + eras_val[j] = 0; } } finish: @@ -447,12 +447,12 @@ int doc_decode_ecc(unsigned char sector[SECTOR_SIZE], unsigned char ecc1[6]) /* init log and exp tables here to save memory. However, it is slower */ Alpha_to = malloc((NN + 1) * sizeof(dtype)); if (!Alpha_to) - return -1; + return -1; Index_of = malloc((NN + 1) * sizeof(dtype)); if (!Index_of) { - free(Alpha_to); - return -1; + free(Alpha_to); + return -1; } generate_gf(Alpha_to, Index_of); @@ -465,48 +465,48 @@ int doc_decode_ecc(unsigned char sector[SECTOR_SIZE], unsigned char ecc1[6]) bb[3] = ((ecc1[3] & 0xc0) >> 6) | ((ecc1[0] & 0xff) << 2); nb_errors = eras_dec_rs(Alpha_to, Index_of, bb, - error_val, error_pos, 0); + error_val, error_pos, 0); if (nb_errors <= 0) - goto the_end; + goto the_end; /* correct the errors */ for(i=0;i= NB_DATA && pos < KK) { - nb_errors = -1; - goto the_end; - } - if (pos < NB_DATA) { - /* extract bit position (MSB first) */ - pos = 10 * (NB_DATA - 1 - pos) - 6; - /* now correct the following 10 bits. At most two bytes - can be modified since pos is even */ - index = (pos >> 3) ^ 1; - bitpos = pos & 7; - if ((index >= 0 && index < SECTOR_SIZE) || - index == (SECTOR_SIZE + 1)) { - val = error_val[i] >> (2 + bitpos); - parity ^= val; - if (index < SECTOR_SIZE) - sector[index] ^= val; - } - index = ((pos >> 3) + 1) ^ 1; - bitpos = (bitpos + 10) & 7; - if (bitpos == 0) - bitpos = 8; - if ((index >= 0 && index < SECTOR_SIZE) || - index == (SECTOR_SIZE + 1)) { - val = error_val[i] << (8 - bitpos); - parity ^= val; - if (index < SECTOR_SIZE) - sector[index] ^= val; - } - } + pos = error_pos[i]; + if (pos >= NB_DATA && pos < KK) { + nb_errors = -1; + goto the_end; + } + if (pos < NB_DATA) { + /* extract bit position (MSB first) */ + pos = 10 * (NB_DATA - 1 - pos) - 6; + /* now correct the following 10 bits. At most two bytes + can be modified since pos is even */ + index = (pos >> 3) ^ 1; + bitpos = pos & 7; + if ((index >= 0 && index < SECTOR_SIZE) || + index == (SECTOR_SIZE + 1)) { + val = error_val[i] >> (2 + bitpos); + parity ^= val; + if (index < SECTOR_SIZE) + sector[index] ^= val; + } + index = ((pos >> 3) + 1) ^ 1; + bitpos = (bitpos + 10) & 7; + if (bitpos == 0) + bitpos = 8; + if ((index >= 0 && index < SECTOR_SIZE) || + index == (SECTOR_SIZE + 1)) { + val = error_val[i] << (8 - bitpos); + parity ^= val; + if (index < SECTOR_SIZE) + sector[index] ^= val; + } + } } /* use parity to test extra errors */ if ((parity & 0xff) != 0) - nb_errors = -1; + nb_errors = -1; the_end: free(Alpha_to); -- cgit v1.2.1