Merge ../linus

Conflicts:

	drivers/cpufreq/cpufreq.c

1 files changed, 0 insertions, 853 deletions

diff --git a/drivers/char/ftape/lowlevel/ftape-ecc.c b/drivers/char/ftape/lowlevel/ftape-ecc.c
deleted file mode 100644
index e5632f674bc8..000000000000
--- a/drivers/char/ftape/lowlevel/ftape-ecc.c
+++ /dev/null
@@ -1,853 +0,0 @@
-/*
- *
- *      Copyright (c) 1993 Ning and David Mosberger.
- 
- This is based on code originally written by Bas Laarhoven (bas@vimec.nl)
- and David L. Brown, Jr., and incorporates improvements suggested by
- Kai Harrekilde-Petersen.
-
- This program 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 program 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 program; see the file COPYING.  If not, write to
- the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139,
- USA.
-
- *
- * $Source: /homes/cvs/ftape-stacked/ftape/lowlevel/ftape-ecc.c,v $
- * $Revision: 1.3 $
- * $Date: 1997/10/05 19:18:10 $
- *
- *      This file contains the Reed-Solomon error correction code 
- *      for the QIC-40/80 floppy-tape driver for Linux.
- */
-
-#include <linux/ftape.h>
-
-#include "../lowlevel/ftape-tracing.h"
-#include "../lowlevel/ftape-ecc.h"
-
-/* Machines that are big-endian should define macro BIG_ENDIAN.
- * Unfortunately, there doesn't appear to be a standard include file
- * that works for all OSs.
- */
-
-#if defined(__sparc__) || defined(__hppa)
-#define BIG_ENDIAN
-#endif				/* __sparc__ || __hppa */
-
-#if defined(__mips__)
-#error Find a smart way to determine the Endianness of the MIPS CPU
-#endif
-
-/* Notice: to minimize the potential for confusion, we use r to
- *         denote the independent variable of the polynomials in the
- *         Galois Field GF(2^8).  We reserve x for polynomials that
- *         that have coefficients in GF(2^8).
- *         
- * The Galois Field in which coefficient arithmetic is performed are
- * the polynomials over Z_2 (i.e., 0 and 1) modulo the irreducible
- * polynomial f(r), where f(r)=r^8 + r^7 + r^2 + r + 1.  A polynomial
- * is represented as a byte with the MSB as the coefficient of r^7 and
- * the LSB as the coefficient of r^0.  For example, the binary
- * representation of f(x) is 0x187 (of course, this doesn't fit into 8
- * bits).  In this field, the polynomial r is a primitive element.
- * That is, r^i with i in 0,...,255 enumerates all elements in the
- * field.
- *
- * The generator polynomial for the QIC-80 ECC is
- *
- *      g(x) = x^3 + r^105*x^2 + r^105*x + 1
- *
- * which can be factored into:
- *
- *      g(x) = (x-r^-1)(x-r^0)(x-r^1)
- *
- * the byte representation of the coefficients are:
- *
- *      r^105 = 0xc0
- *      r^-1  = 0xc3
- *      r^0   = 0x01
- *      r^1   = 0x02
- *
- * Notice that r^-1 = r^254 as exponent arithmetic is performed
- * modulo 2^8-1 = 255.
- *
- * For more information on Galois Fields and Reed-Solomon codes, refer
- * to any good book.  I found _An Introduction to Error Correcting
- * Codes with Applications_ by S. A. Vanstone and P. C. van Oorschot
- * to be a good introduction into the former.  _CODING THEORY: The
- * Essentials_ I found very useful for its concise description of
- * Reed-Solomon encoding/decoding.
- *
- */
-
-typedef __u8 Matrix[3][3];
-
-/*
- * gfpow[] is defined such that gfpow[i] returns r^i if
- * i is in the range [0..255].
- */
-static const __u8 gfpow[] =
-{
-	0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80,
-	0x87, 0x89, 0x95, 0xad, 0xdd, 0x3d, 0x7a, 0xf4,
-	0x6f, 0xde, 0x3b, 0x76, 0xec, 0x5f, 0xbe, 0xfb,
-	0x71, 0xe2, 0x43, 0x86, 0x8b, 0x91, 0xa5, 0xcd,
-	0x1d, 0x3a, 0x74, 0xe8, 0x57, 0xae, 0xdb, 0x31,
-	0x62, 0xc4, 0x0f, 0x1e, 0x3c, 0x78, 0xf0, 0x67,
-	0xce, 0x1b, 0x36, 0x6c, 0xd8, 0x37, 0x6e, 0xdc,
-	0x3f, 0x7e, 0xfc, 0x7f, 0xfe, 0x7b, 0xf6, 0x6b,
-	0xd6, 0x2b, 0x56, 0xac, 0xdf, 0x39, 0x72, 0xe4,
-	0x4f, 0x9e, 0xbb, 0xf1, 0x65, 0xca, 0x13, 0x26,
-	0x4c, 0x98, 0xb7, 0xe9, 0x55, 0xaa, 0xd3, 0x21,
-	0x42, 0x84, 0x8f, 0x99, 0xb5, 0xed, 0x5d, 0xba,
-	0xf3, 0x61, 0xc2, 0x03, 0x06, 0x0c, 0x18, 0x30,
-	0x60, 0xc0, 0x07, 0x0e, 0x1c, 0x38, 0x70, 0xe0,
-	0x47, 0x8e, 0x9b, 0xb1, 0xe5, 0x4d, 0x9a, 0xb3,
-	0xe1, 0x45, 0x8a, 0x93, 0xa1, 0xc5, 0x0d, 0x1a,
-	0x34, 0x68, 0xd0, 0x27, 0x4e, 0x9c, 0xbf, 0xf9,
-	0x75, 0xea, 0x53, 0xa6, 0xcb, 0x11, 0x22, 0x44,
-	0x88, 0x97, 0xa9, 0xd5, 0x2d, 0x5a, 0xb4, 0xef,
-	0x59, 0xb2, 0xe3, 0x41, 0x82, 0x83, 0x81, 0x85,
-	0x8d, 0x9d, 0xbd, 0xfd, 0x7d, 0xfa, 0x73, 0xe6,
-	0x4b, 0x96, 0xab, 0xd1, 0x25, 0x4a, 0x94, 0xaf,
-	0xd9, 0x35, 0x6a, 0xd4, 0x2f, 0x5e, 0xbc, 0xff,
-	0x79, 0xf2, 0x63, 0xc6, 0x0b, 0x16, 0x2c, 0x58,
-	0xb0, 0xe7, 0x49, 0x92, 0xa3, 0xc1, 0x05, 0x0a,
-	0x14, 0x28, 0x50, 0xa0, 0xc7, 0x09, 0x12, 0x24,
-	0x48, 0x90, 0xa7, 0xc9, 0x15, 0x2a, 0x54, 0xa8,
-	0xd7, 0x29, 0x52, 0xa4, 0xcf, 0x19, 0x32, 0x64,
-	0xc8, 0x17, 0x2e, 0x5c, 0xb8, 0xf7, 0x69, 0xd2,
-	0x23, 0x46, 0x8c, 0x9f, 0xb9, 0xf5, 0x6d, 0xda,
-	0x33, 0x66, 0xcc, 0x1f, 0x3e, 0x7c, 0xf8, 0x77,
-	0xee, 0x5b, 0xb6, 0xeb, 0x51, 0xa2, 0xc3, 0x01
-};
-
-/*
- * This is a log table.  That is, gflog[r^i] returns i (modulo f(r)).
- * gflog[0] is undefined and the first element is therefore not valid.
- */
-static const __u8 gflog[256] =
-{
-	0xff, 0x00, 0x01, 0x63, 0x02, 0xc6, 0x64, 0x6a,
-	0x03, 0xcd, 0xc7, 0xbc, 0x65, 0x7e, 0x6b, 0x2a,
-	0x04, 0x8d, 0xce, 0x4e, 0xc8, 0xd4, 0xbd, 0xe1,
-	0x66, 0xdd, 0x7f, 0x31, 0x6c, 0x20, 0x2b, 0xf3,
-	0x05, 0x57, 0x8e, 0xe8, 0xcf, 0xac, 0x4f, 0x83,
-	0xc9, 0xd9, 0xd5, 0x41, 0xbe, 0x94, 0xe2, 0xb4,
-	0x67, 0x27, 0xde, 0xf0, 0x80, 0xb1, 0x32, 0x35,
-	0x6d, 0x45, 0x21, 0x12, 0x2c, 0x0d, 0xf4, 0x38,
-	0x06, 0x9b, 0x58, 0x1a, 0x8f, 0x79, 0xe9, 0x70,
-	0xd0, 0xc2, 0xad, 0xa8, 0x50, 0x75, 0x84, 0x48,
-	0xca, 0xfc, 0xda, 0x8a, 0xd6, 0x54, 0x42, 0x24,
-	0xbf, 0x98, 0x95, 0xf9, 0xe3, 0x5e, 0xb5, 0x15,
-	0x68, 0x61, 0x28, 0xba, 0xdf, 0x4c, 0xf1, 0x2f,
-	0x81, 0xe6, 0xb2, 0x3f, 0x33, 0xee, 0x36, 0x10,
-	0x6e, 0x18, 0x46, 0xa6, 0x22, 0x88, 0x13, 0xf7,
-	0x2d, 0xb8, 0x0e, 0x3d, 0xf5, 0xa4, 0x39, 0x3b,
-	0x07, 0x9e, 0x9c, 0x9d, 0x59, 0x9f, 0x1b, 0x08,
-	0x90, 0x09, 0x7a, 0x1c, 0xea, 0xa0, 0x71, 0x5a,
-	0xd1, 0x1d, 0xc3, 0x7b, 0xae, 0x0a, 0xa9, 0x91,
-	0x51, 0x5b, 0x76, 0x72, 0x85, 0xa1, 0x49, 0xeb,
-	0xcb, 0x7c, 0xfd, 0xc4, 0xdb, 0x1e, 0x8b, 0xd2,
-	0xd7, 0x92, 0x55, 0xaa, 0x43, 0x0b, 0x25, 0xaf,
-	0xc0, 0x73, 0x99, 0x77, 0x96, 0x5c, 0xfa, 0x52,
-	0xe4, 0xec, 0x5f, 0x4a, 0xb6, 0xa2, 0x16, 0x86,
-	0x69, 0xc5, 0x62, 0xfe, 0x29, 0x7d, 0xbb, 0xcc,
-	0xe0, 0xd3, 0x4d, 0x8c, 0xf2, 0x1f, 0x30, 0xdc,
-	0x82, 0xab, 0xe7, 0x56, 0xb3, 0x93, 0x40, 0xd8,
-	0x34, 0xb0, 0xef, 0x26, 0x37, 0x0c, 0x11, 0x44,
-	0x6f, 0x78, 0x19, 0x9a, 0x47, 0x74, 0xa7, 0xc1,
-	0x23, 0x53, 0x89, 0xfb, 0x14, 0x5d, 0xf8, 0x97,
-	0x2e, 0x4b, 0xb9, 0x60, 0x0f, 0xed, 0x3e, 0xe5,
-	0xf6, 0x87, 0xa5, 0x17, 0x3a, 0xa3, 0x3c, 0xb7
-};
-
-/* This is a multiplication table for the factor 0xc0 (i.e., r^105 (mod f(r)).
- * gfmul_c0[f] returns r^105 * f(r) (modulo f(r)).
- */
-static const __u8 gfmul_c0[256] =
-{
-	0x00, 0xc0, 0x07, 0xc7, 0x0e, 0xce, 0x09, 0xc9,
-	0x1c, 0xdc, 0x1b, 0xdb, 0x12, 0xd2, 0x15, 0xd5,
-	0x38, 0xf8, 0x3f, 0xff, 0x36, 0xf6, 0x31, 0xf1,
-	0x24, 0xe4, 0x23, 0xe3, 0x2a, 0xea, 0x2d, 0xed,
-	0x70, 0xb0, 0x77, 0xb7, 0x7e, 0xbe, 0x79, 0xb9,
-	0x6c, 0xac, 0x6b, 0xab, 0x62, 0xa2, 0x65, 0xa5,
-	0x48, 0x88, 0x4f, 0x8f, 0x46, 0x86, 0x41, 0x81,
-	0x54, 0x94, 0x53, 0x93, 0x5a, 0x9a, 0x5d, 0x9d,
-	0xe0, 0x20, 0xe7, 0x27, 0xee, 0x2e, 0xe9, 0x29,
-	0xfc, 0x3c, 0xfb, 0x3b, 0xf2, 0x32, 0xf5, 0x35,
-	0xd8, 0x18, 0xdf, 0x1f, 0xd6, 0x16, 0xd1, 0x11,
-	0xc4, 0x04, 0xc3, 0x03, 0xca, 0x0a, 0xcd, 0x0d,
-	0x90, 0x50, 0x97, 0x57, 0x9e, 0x5e, 0x99, 0x59,
-	0x8c, 0x4c, 0x8b, 0x4b, 0x82, 0x42, 0x85, 0x45,
-	0xa8, 0x68, 0xaf, 0x6f, 0xa6, 0x66, 0xa1, 0x61,
-	0xb4, 0x74, 0xb3, 0x73, 0xba, 0x7a, 0xbd, 0x7d,
-	0x47, 0x87, 0x40, 0x80, 0x49, 0x89, 0x4e, 0x8e,
-	0x5b, 0x9b, 0x5c, 0x9c, 0x55, 0x95, 0x52, 0x92,
-	0x7f, 0xbf, 0x78, 0xb8, 0x71, 0xb1, 0x76, 0xb6,
-	0x63, 0xa3, 0x64, 0xa4, 0x6d, 0xad, 0x6a, 0xaa,
-	0x37, 0xf7, 0x30, 0xf0, 0x39, 0xf9, 0x3e, 0xfe,
-	0x2b, 0xeb, 0x2c, 0xec, 0x25, 0xe5, 0x22, 0xe2,
-	0x0f, 0xcf, 0x08, 0xc8, 0x01, 0xc1, 0x06, 0xc6,
-	0x13, 0xd3, 0x14, 0xd4, 0x1d, 0xdd, 0x1a, 0xda,
-	0xa7, 0x67, 0xa0, 0x60, 0xa9, 0x69, 0xae, 0x6e,
-	0xbb, 0x7b, 0xbc, 0x7c, 0xb5, 0x75, 0xb2, 0x72,
-	0x9f, 0x5f, 0x98, 0x58, 0x91, 0x51, 0x96, 0x56,
-	0x83, 0x43, 0x84, 0x44, 0x8d, 0x4d, 0x8a, 0x4a,
-	0xd7, 0x17, 0xd0, 0x10, 0xd9, 0x19, 0xde, 0x1e,
-	0xcb, 0x0b, 0xcc, 0x0c, 0xc5, 0x05, 0xc2, 0x02,
-	0xef, 0x2f, 0xe8, 0x28, 0xe1, 0x21, 0xe6, 0x26,
-	0xf3, 0x33, 0xf4, 0x34, 0xfd, 0x3d, 0xfa, 0x3a
-};
-
-
-/* Returns V modulo 255 provided V is in the range -255,-254,...,509.
- */
-static inline __u8 mod255(int v)
-{
-	if (v > 0) {
-		if (v < 255) {
-			return v;
-		} else {
-			return v - 255;
-		}
-	} else {
-		return v + 255;
-	}
-}
-
-
-/* Add two numbers in the field.  Addition in this field is equivalent
- * to a bit-wise exclusive OR operation---subtraction is therefore
- * identical to addition.
- */
-static inline __u8 gfadd(__u8 a, __u8 b)
-{
-	return a ^ b;
-}
-
-
-/* Add two vectors of numbers in the field.  Each byte in A and B gets
- * added individually.
- */
-static inline unsigned long gfadd_long(unsigned long a, unsigned long b)
-{
-	return a ^ b;
-}
-
-
-/* Multiply two numbers in the field:
- */
-static inline __u8 gfmul(__u8 a, __u8 b)
-{
-	if (a && b) {
-		return gfpow[mod255(gflog[a] + gflog[b])];
-	} else {
-		return 0;
-	}
-}
-
-
-/* Just like gfmul, except we have already looked up the log of the
- * second number.
- */
-static inline __u8 gfmul_exp(__u8 a, int b)
-{
-	if (a) {
-		return gfpow[mod255(gflog[a] + b)];
-	} else {
-		return 0;
-	}
-}
-
-
-/* Just like gfmul_exp, except that A is a vector of numbers.  That
- * is, each byte in A gets multiplied by gfpow[mod255(B)].
- */
-static inline unsigned long gfmul_exp_long(unsigned long a, int b)
-{
-	__u8 t;
-
-	if (sizeof(long) == 4) {
-		return (
-		((t = (__u32)a >> 24 & 0xff) ?
-		 (((__u32) gfpow[mod255(gflog[t] + b)]) << 24) : 0) |
-		((t = (__u32)a >> 16 & 0xff) ?
-		 (((__u32) gfpow[mod255(gflog[t] + b)]) << 16) : 0) |
-		((t = (__u32)a >> 8 & 0xff) ?
-		 (((__u32) gfpow[mod255(gflog[t] + b)]) << 8) : 0) |
-		((t = (__u32)a >> 0 & 0xff) ?
-		 (((__u32) gfpow[mod255(gflog[t] + b)]) << 0) : 0));
-	} else if (sizeof(long) == 8) {
-		return (
-		((t = (__u64)a >> 56 & 0xff) ?
-		 (((__u64) gfpow[mod255(gflog[t] + b)]) << 56) : 0) |
-		((t = (__u64)a >> 48 & 0xff) ?
-		 (((__u64) gfpow[mod255(gflog[t] + b)]) << 48) : 0) |
-		((t = (__u64)a >> 40 & 0xff) ?
-		 (((__u64) gfpow[mod255(gflog[t] + b)]) << 40) : 0) |
-		((t = (__u64)a >> 32 & 0xff) ?
-		 (((__u64) gfpow[mod255(gflog[t] + b)]) << 32) : 0) |
-		((t = (__u64)a >> 24 & 0xff) ?
-		 (((__u64) gfpow[mod255(gflog[t] + b)]) << 24) : 0) |
-		((t = (__u64)a >> 16 & 0xff) ?
-		 (((__u64) gfpow[mod255(gflog[t] + b)]) << 16) : 0) |
-		((t = (__u64)a >> 8 & 0xff) ?
-		 (((__u64) gfpow[mod255(gflog[t] + b)]) << 8) : 0) |
-		((t = (__u64)a >> 0 & 0xff) ?
-		 (((__u64) gfpow[mod255(gflog[t] + b)]) << 0) : 0));
-	} else {
-		TRACE_FUN(ft_t_any);
-		TRACE_ABORT(-1, ft_t_err, "Error: size of long is %d bytes",
-			    (int)sizeof(long));
-	}
-}
-
-
-/* Divide two numbers in the field.  Returns a/b (modulo f(x)).
- */
-static inline __u8 gfdiv(__u8 a, __u8 b)
-{
-	if (!b) {
-		TRACE_FUN(ft_t_any);
-		TRACE_ABORT(0xff, ft_t_bug, "Error: division by zero");
-	} else if (a == 0) {
-		return 0;
-	} else {
-		return gfpow[mod255(gflog[a] - gflog[b])];
-	}
-}
-
-
-/* The following functions return the inverse of the matrix of the
- * linear system that needs to be solved to determine the error
- * magnitudes.  The first deals with matrices of rank 3, while the
- * second deals with matrices of rank 2.  The error indices are passed
- * in arguments L0,..,L2 (0=first sector, 31=last sector).  The error
- * indices must be sorted in ascending order, i.e., L0<L1<L2.
- *
- * The linear system that needs to be solved for the error magnitudes
- * is A * b = s, where s is the known vector of syndromes, b is the
- * vector of error magnitudes and A in the ORDER=3 case:
- *
- *    A_3 = {{1/r^L[0], 1/r^L[1], 1/r^L[2]},
- *          {        1,        1,        1},
- *          { r^L[0], r^L[1], r^L[2]}} 
- */
-static inline int gfinv3(__u8 l0,
-			 __u8 l1, 
-			 __u8 l2, 
-			 Matrix Ainv)
-{
-	__u8 det;
-	__u8 t20, t10, t21, t12, t01, t02;
-	int log_det;
-
-	/* compute some intermediate results: */
-	t20 = gfpow[l2 - l0];	        /* t20 = r^l2/r^l0 */
-	t10 = gfpow[l1 - l0];	        /* t10 = r^l1/r^l0 */
-	t21 = gfpow[l2 - l1];	        /* t21 = r^l2/r^l1 */
-	t12 = gfpow[l1 - l2 + 255];	/* t12 = r^l1/r^l2 */
-	t01 = gfpow[l0 - l1 + 255];	/* t01 = r^l0/r^l1 */
-	t02 = gfpow[l0 - l2 + 255];	/* t02 = r^l0/r^l2 */
-	/* Calculate the determinant of matrix A_3^-1 (sometimes
-	 * called the Vandermonde determinant):
-	 */
-	det = gfadd(t20, gfadd(t10, gfadd(t21, gfadd(t12, gfadd(t01, t02)))));
-	if (!det) {
-		TRACE_FUN(ft_t_any);
-		TRACE_ABORT(0, ft_t_err,
-			   "Inversion failed (3 CRC errors, >0 CRC failures)");
-	}
-	log_det = 255 - gflog[det];
-
-	/* Now, calculate all of the coefficients:
-	 */
-	Ainv[0][0]= gfmul_exp(gfadd(gfpow[l1], gfpow[l2]), log_det);
-	Ainv[0][1]= gfmul_exp(gfadd(t21, t12), log_det);
-	Ainv[0][2]= gfmul_exp(gfadd(gfpow[255 - l1], gfpow[255 - l2]),log_det);
-
-	Ainv[1][0]= gfmul_exp(gfadd(gfpow[l0], gfpow[l2]), log_det);
-	Ainv[1][1]= gfmul_exp(gfadd(t20, t02), log_det);
-	Ainv[1][2]= gfmul_exp(gfadd(gfpow[255 - l0], gfpow[255 - l2]),log_det);
-
-	Ainv[2][0]= gfmul_exp(gfadd(gfpow[l0], gfpow[l1]), log_det);
-	Ainv[2][1]= gfmul_exp(gfadd(t10, t01), log_det);
-	Ainv[2][2]= gfmul_exp(gfadd(gfpow[255 - l0], gfpow[255 - l1]),log_det);
-
-	return 1;
-}
-
-
-static inline int gfinv2(__u8 l0, __u8 l1, Matrix Ainv)
-{
-	__u8 det;
-	__u8 t1, t2;
-	int log_det;
-
-	t1 = gfpow[255 - l0];
-	t2 = gfpow[255 - l1];
-	det = gfadd(t1, t2);
-	if (!det) {
-		TRACE_FUN(ft_t_any);
-		TRACE_ABORT(0, ft_t_err,
-			   "Inversion failed (2 CRC errors, >0 CRC failures)");
-	}
-	log_det = 255 - gflog[det];
-
-	/* Now, calculate all of the coefficients:
-	 */
-	Ainv[0][0] = Ainv[1][0] = gfpow[log_det];
-
-	Ainv[0][1] = gfmul_exp(t2, log_det);
-	Ainv[1][1] = gfmul_exp(t1, log_det);
-
-	return 1;
-}
-
-
-/* Multiply matrix A by vector S and return result in vector B.  M is
- * assumed to be of order NxN, S and B of order Nx1.
- */
-static inline void gfmat_mul(int n, Matrix A, 
-			     __u8 *s, __u8 *b)
-{
-	int i, j;
-	__u8 dot_prod;
-
-	for (i = 0; i < n; ++i) {
-		dot_prod = 0;
-		for (j = 0; j < n; ++j) {
-			dot_prod = gfadd(dot_prod, gfmul(A[i][j], s[j]));
-		}
-		b[i] = dot_prod;
-	}
-}
-
-
-
-/* The Reed Solomon ECC codes are computed over the N-th byte of each
- * block, where N=SECTOR_SIZE.  There are up to 29 blocks of data, and
- * 3 blocks of ECC.  The blocks are stored contiguously in memory.  A
- * segment, consequently, is assumed to have at least 4 blocks: one or
- * more data blocks plus three ECC blocks.
- *
- * Notice: In QIC-80 speak, a CRC error is a sector with an incorrect
- *         CRC.  A CRC failure is a sector with incorrect data, but
- *         a valid CRC.  In the error control literature, the former
- *         is usually called "erasure", the latter "error."
- */
-/* Compute the parity bytes for C columns of data, where C is the
- * number of bytes that fit into a long integer.  We use a linear
- * feed-back register to do this.  The parity bytes P[0], P[STRIDE],
- * P[2*STRIDE] are computed such that:
- *
- *              x^k * p(x) + m(x) = 0 (modulo g(x))
- *
- * where k = NBLOCKS,
- *       p(x) = P[0] + P[STRIDE]*x + P[2*STRIDE]*x^2, and
- *       m(x) = sum_{i=0}^k m_i*x^i.
- *       m_i = DATA[i*SECTOR_SIZE]
- */
-static inline void set_parity(unsigned long *data,
-			      int nblocks, 
-			      unsigned long *p, 
-			      int stride)
-{
-	unsigned long p0, p1, p2, t1, t2, *end;
-
-	end = data + nblocks * (FT_SECTOR_SIZE / sizeof(long));
-	p0 = p1 = p2 = 0;
-	while (data < end) {
-		/* The new parity bytes p0_i, p1_i, p2_i are computed
-		 * from the old values p0_{i-1}, p1_{i-1}, p2_{i-1}
-		 * recursively as:
-		 *
-		 *        p0_i = p1_{i-1} + r^105 * (m_{i-1} - p0_{i-1})
-		 *        p1_i = p2_{i-1} + r^105 * (m_{i-1} - p0_{i-1})
-		 *        p2_i =                    (m_{i-1} - p0_{i-1})
-		 *
-		 * With the initial condition: p0_0 = p1_0 = p2_0 = 0.
-		 */
-		t1 = gfadd_long(*data, p0);
-		/*
-		 * Multiply each byte in t1 by 0xc0:
-		 */
-		if (sizeof(long) == 4) {
-			t2= (((__u32) gfmul_c0[(__u32)t1 >> 24 & 0xff]) << 24 |
-			     ((__u32) gfmul_c0[(__u32)t1 >> 16 & 0xff]) << 16 |
-			     ((__u32) gfmul_c0[(__u32)t1 >>  8 & 0xff]) <<  8 |
-			     ((__u32) gfmul_c0[(__u32)t1 >>  0 & 0xff]) <<  0);
-		} else if (sizeof(long) == 8) {
-			t2= (((__u64) gfmul_c0[(__u64)t1 >> 56 & 0xff]) << 56 |
-			     ((__u64) gfmul_c0[(__u64)t1 >> 48 & 0xff]) << 48 |
-			     ((__u64) gfmul_c0[(__u64)t1 >> 40 & 0xff]) << 40 |
-			     ((__u64) gfmul_c0[(__u64)t1 >> 32 & 0xff]) << 32 |
-			     ((__u64) gfmul_c0[(__u64)t1 >> 24 & 0xff]) << 24 |
-			     ((__u64) gfmul_c0[(__u64)t1 >> 16 & 0xff]) << 16 |
-			     ((__u64) gfmul_c0[(__u64)t1 >>  8 & 0xff]) <<  8 |
-			     ((__u64) gfmul_c0[(__u64)t1 >>  0 & 0xff]) <<  0);
-		} else {
-			TRACE_FUN(ft_t_any);
-			TRACE(ft_t_err, "Error: long is of size %d",
-			      (int) sizeof(long));
-			TRACE_EXIT;
-		}
-		p0 = gfadd_long(t2, p1);
-		p1 = gfadd_long(t2, p2);
-		p2 = t1;
-		data += FT_SECTOR_SIZE / sizeof(long);
-	}
-	*p = p0;
-	p += stride;
-	*p = p1;
-	p += stride;
-	*p = p2;
-	return;
-}
-
-
-/* Compute the 3 syndrome values.  DATA should point to the first byte
- * of the column for which the syndromes are desired.  The syndromes
- * are computed over the first NBLOCKS of rows.  The three bytes will
- * be placed in S[0], S[1], and S[2].
- *
- * S[i] is the value of the "message" polynomial m(x) evaluated at the
- * i-th root of the generator polynomial g(x).
- *
- * As g(x)=(x-r^-1)(x-1)(x-r^1) we evaluate the message polynomial at
- * x=r^-1 to get S[0], at x=r^0=1 to get S[1], and at x=r to get S[2].
- * This could be done directly and efficiently via the Horner scheme.
- * However, it would require multiplication tables for the factors
- * r^-1 (0xc3) and r (0x02).  The following scheme does not require
- * any multiplication tables beyond what's needed for set_parity()
- * anyway and is slightly faster if there are no errors and slightly
- * slower if there are errors.  The latter is hopefully the infrequent
- * case.
- *
- * To understand the alternative algorithm, notice that set_parity(m,
- * k, p) computes parity bytes such that:
- *
- *      x^k * p(x) = m(x) (modulo g(x)).
- *
- * That is, to evaluate m(r^m), where r^m is a root of g(x), we can
- * simply evaluate (r^m)^k*p(r^m).  Also, notice that p is 0 if and
- * only if s is zero.  That is, if all parity bytes are 0, we know
- * there is no error in the data and consequently there is no need to
- * compute s(x) at all!  In all other cases, we compute s(x) from p(x)
- * by evaluating (r^m)^k*p(r^m) for m=-1, m=0, and m=1.  The p(x)
- * polynomial is evaluated via the Horner scheme.
- */
-static int compute_syndromes(unsigned long *data, int nblocks, unsigned long *s)
-{
-	unsigned long p[3];
-
-	set_parity(data, nblocks, p, 1);
-	if (p[0] | p[1] | p[2]) {
-		/* Some of the checked columns do not have a zero
-		 * syndrome.  For simplicity, we compute the syndromes
-		 * for all columns that we have computed the
-		 * remainders for.
-		 */
-		s[0] = gfmul_exp_long(
-			gfadd_long(p[0], 
-				   gfmul_exp_long(
-					   gfadd_long(p[1], 
-						      gfmul_exp_long(p[2], -1)),
-					   -1)), 
-			-nblocks);
-		s[1] = gfadd_long(gfadd_long(p[2], p[1]), p[0]);
-		s[2] = gfmul_exp_long(
-			gfadd_long(p[0], 
-				   gfmul_exp_long(
-					   gfadd_long(p[1],
-						      gfmul_exp_long(p[2], 1)),
-					   1)),
-			nblocks);
-		return 0;
-	} else {
-		return 1;
-	}
-}
-
-
-/* Correct the block in the column pointed to by DATA.  There are NBAD
- * CRC errors and their indices are in BAD_LOC[0], up to
- * BAD_LOC[NBAD-1].  If NBAD>1, Ainv holds the inverse of the matrix
- * of the linear system that needs to be solved to determine the error
- * magnitudes.  S[0], S[1], and S[2] are the syndrome values.  If row
- * j gets corrected, then bit j will be set in CORRECTION_MAP.
- */
-static inline int correct_block(__u8 *data, int nblocks,
-				int nbad, int *bad_loc, Matrix Ainv,
-				__u8 *s,
-				SectorMap * correction_map)
-{
-	int ncorrected = 0;
-	int i;
-	__u8 t1, t2;
-	__u8 c0, c1, c2;	/* check bytes */
-	__u8 error_mag[3], log_error_mag;
-	__u8 *dp, l, e;
-	TRACE_FUN(ft_t_any);
-
-	switch (nbad) {
-	case 0:
-		/* might have a CRC failure: */
-		if (s[0] == 0) {
-			/* more than one error */
-			TRACE_ABORT(-1, ft_t_err,
-				 "ECC failed (0 CRC errors, >1 CRC failures)");
-		}
-		t1 = gfdiv(s[1], s[0]);
-		if ((bad_loc[nbad++] = gflog[t1]) >= nblocks) {
-			TRACE(ft_t_err,
-			      "ECC failed (0 CRC errors, >1 CRC failures)");
-			TRACE_ABORT(-1, ft_t_err,
-				  "attempt to correct data at %d", bad_loc[0]);
-		}
-		error_mag[0] = s[1];
-		break;
-	case 1:
-		t1 = gfadd(gfmul_exp(s[1], bad_loc[0]), s[2]);
-		t2 = gfadd(gfmul_exp(s[0], bad_loc[0]), s[1]);
-		if (t1 == 0 && t2 == 0) {
-			/* one erasure, no error: */
-			Ainv[0][0] = gfpow[bad_loc[0]];
-		} else if (t1 == 0 || t2 == 0) {
-			/* one erasure and more than one error: */
-			TRACE_ABORT(-1, ft_t_err,
-				    "ECC failed (1 erasure, >1 error)");
-		} else {
-			/* one erasure, one error: */
-			if ((bad_loc[nbad++] = gflog[gfdiv(t1, t2)]) 
-			    >= nblocks) {
-				TRACE(ft_t_err, "ECC failed "
-				      "(1 CRC errors, >1 CRC failures)");
-				TRACE_ABORT(-1, ft_t_err,
-					    "attempt to correct data at %d",
-					    bad_loc[1]);
-			}
-			if (!gfinv2(bad_loc[0], bad_loc[1], Ainv)) {
-				/* inversion failed---must have more
-                                 *  than one error 
-				 */
-				TRACE_EXIT -1;
-			}
-		}
-		/* FALL THROUGH TO ERROR MAGNITUDE COMPUTATION:
-		 */
-	case 2:
-	case 3:
-		/* compute error magnitudes: */
-		gfmat_mul(nbad, Ainv, s, error_mag);
-		break;
-
-	default:
-		TRACE_ABORT(-1, ft_t_err,
-			    "Internal Error: number of CRC errors > 3");
-	}
-
-	/* Perform correction by adding ERROR_MAG[i] to the byte at
-	 * offset BAD_LOC[i].  Also add the value of the computed
-	 * error polynomial to the syndrome values.  If the correction
-	 * was successful, the resulting check bytes should be zero
-	 * (i.e., the corrected data is a valid code word).
-	 */
-	c0 = s[0];
-	c1 = s[1];
-	c2 = s[2];
-	for (i = 0; i < nbad; ++i) {
-		e = error_mag[i];
-		if (e) {
-			/* correct the byte at offset L by magnitude E: */
-			l = bad_loc[i];
-			dp = &data[l * FT_SECTOR_SIZE];
-			*dp = gfadd(*dp, e);
-			*correction_map |= 1 << l;
-			++ncorrected;
-
-			log_error_mag = gflog[e];
-			c0 = gfadd(c0, gfpow[mod255(log_error_mag - l)]);
-			c1 = gfadd(c1, e);
-			c2 = gfadd(c2, gfpow[mod255(log_error_mag + l)]);
-		}
-	}
-	if (c0 || c1 || c2) {
-		TRACE_ABORT(-1, ft_t_err,
-			    "ECC self-check failed, too many errors");
-	}
-	TRACE_EXIT ncorrected;
-}
-
-
-#if defined(ECC_SANITY_CHECK) || defined(ECC_PARANOID)
-
-/* Perform a sanity check on the computed parity bytes:
- */
-static int sanity_check(unsigned long *data, int nblocks)
-{
-	TRACE_FUN(ft_t_any);
-	unsigned long s[3];
-
-	if (!compute_syndromes(data, nblocks, s)) {
-		TRACE_ABORT(0, ft_bug,
-			    "Internal Error: syndrome self-check failed");
-	}
-	TRACE_EXIT 1;
-}
-
-#endif /* defined(ECC_SANITY_CHECK) || defined(ECC_PARANOID) */
-
-/* Compute the parity for an entire segment of data.
- */
-int ftape_ecc_set_segment_parity(struct memory_segment *mseg)
-{
-	int i;
-	__u8 *parity_bytes;
-
-	parity_bytes = &mseg->data[(mseg->blocks - 3) * FT_SECTOR_SIZE];
-	for (i = 0; i < FT_SECTOR_SIZE; i += sizeof(long)) {
-		set_parity((unsigned long *) &mseg->data[i], mseg->blocks - 3,
-			   (unsigned long *) &parity_bytes[i],
-			   FT_SECTOR_SIZE / sizeof(long));
-#ifdef ECC_PARANOID
-		if (!sanity_check((unsigned long *) &mseg->data[i],
-				   mseg->blocks)) {
-			return -1;
-		}
-#endif				/* ECC_PARANOID */
-	}
-	return 0;
-}
-
-
-/* Checks and corrects (if possible) the segment MSEG.  Returns one of
- * ECC_OK, ECC_CORRECTED, and ECC_FAILED.
- */
-int ftape_ecc_correct_data(struct memory_segment *mseg)
-{
-	int col, i, result;
-	int ncorrected = 0;
-	int nerasures = 0;	/* # of erasures (CRC errors) */
-	int erasure_loc[3];	/* erasure locations */
-	unsigned long ss[3];
-	__u8 s[3];
-	Matrix Ainv;
-	TRACE_FUN(ft_t_flow);
-
-	mseg->corrected = 0;
-
-	/* find first column that has non-zero syndromes: */
-	for (col = 0; col < FT_SECTOR_SIZE; col += sizeof(long)) {
-		if (!compute_syndromes((unsigned long *) &mseg->data[col],
-				       mseg->blocks, ss)) {
-			/* something is wrong---have to fix things */
-			break;
-		}
-	}
-	if (col >= FT_SECTOR_SIZE) {
-		/* all syndromes are ok, therefore nothing to correct */
-		TRACE_EXIT ECC_OK;
-	}
-	/* count the number of CRC errors if there were any: */
-	if (mseg->read_bad) {
-		for (i = 0; i < mseg->blocks; i++) {
-			if (BAD_CHECK(mseg->read_bad, i)) {
-				if (nerasures >= 3) {
-					/* this is too much for ECC */
-					TRACE_ABORT(ECC_FAILED, ft_t_err,
-						"ECC failed (>3 CRC errors)");
-				}	/* if */
-				erasure_loc[nerasures++] = i;
-			}
-		}
-	}
-	/*
-	 * If there are at least 2 CRC errors, determine inverse of matrix
-	 * of linear system to be solved:
-	 */
-	switch (nerasures) {
-	case 2:
-		if (!gfinv2(erasure_loc[0], erasure_loc[1], Ainv)) {
-			TRACE_EXIT ECC_FAILED;
-		}
-		break;
-	case 3:
-		if (!gfinv3(erasure_loc[0], erasure_loc[1],
-			    erasure_loc[2], Ainv)) {
-			TRACE_EXIT ECC_FAILED;
-		}
-		break;
-	default:
-		/* this is not an error condition... */
-		break;
-	}
-
-	do {
-		for (i = 0; i < sizeof(long); ++i) {
-			s[0] = ss[0];
-			s[1] = ss[1];
-			s[2] = ss[2];
-			if (s[0] | s[1] | s[2]) {
-#ifdef BIG_ENDIAN
-				result = correct_block(
-					&mseg->data[col + sizeof(long) - 1 - i],
-					mseg->blocks,
-					nerasures,
-					erasure_loc,
-					Ainv,
-					s,
-					&mseg->corrected);
-#else
-				result = correct_block(&mseg->data[col + i],
-						       mseg->blocks,
-						       nerasures,
-						       erasure_loc,
-						       Ainv,
-						       s,
-						       &mseg->corrected);
-#endif
-				if (result < 0) {
-					TRACE_EXIT ECC_FAILED;
-				}
-				ncorrected += result;
-			}
-			ss[0] >>= 8;
-			ss[1] >>= 8;
-			ss[2] >>= 8;
-		}
-
-#ifdef ECC_SANITY_CHECK
-		if (!sanity_check((unsigned long *) &mseg->data[col],
-				  mseg->blocks)) {
-			TRACE_EXIT ECC_FAILED;
-		}
-#endif				/* ECC_SANITY_CHECK */
-
-		/* find next column with non-zero syndromes: */
-		while ((col += sizeof(long)) < FT_SECTOR_SIZE) {
-			if (!compute_syndromes((unsigned long *)
-				    &mseg->data[col], mseg->blocks, ss)) {
-				/* something is wrong---have to fix things */
-				break;
-			}
-		}
-	} while (col < FT_SECTOR_SIZE);
-	if (ncorrected && nerasures == 0) {
-		TRACE(ft_t_warn, "block contained error not caught by CRC");
-	}
-	TRACE((ncorrected > 0) ? ft_t_noise : ft_t_any, "number of corrections: %d", ncorrected);
-	TRACE_EXIT ncorrected ? ECC_CORRECTED : ECC_OK;
-}