// SPDX-License-Identifier: BSD-2-Clause
/**********************************************************************
 * Copyright(c) 2011-2015 Intel Corporation All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *    Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *    Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *    Neither the name of Intel Corporation nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <linux/limits.h>
#include <linux/string.h>	/* for memset */
#include <libcfs/libcfs.h>
#include "erasure_code.h"

/* Global GF(256) tables */
static const unsigned char gff_base[] = {
	0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1d, 0x3a,
	0x74, 0xe8, 0xcd, 0x87, 0x13, 0x26, 0x4c, 0x98, 0x2d, 0x5a,
	0xb4, 0x75, 0xea, 0xc9, 0x8f, 0x03, 0x06, 0x0c, 0x18, 0x30,
	0x60, 0xc0, 0x9d, 0x27, 0x4e, 0x9c, 0x25, 0x4a, 0x94, 0x35,
	0x6a, 0xd4, 0xb5, 0x77, 0xee, 0xc1, 0x9f, 0x23, 0x46, 0x8c,
	0x05, 0x0a, 0x14, 0x28, 0x50, 0xa0, 0x5d, 0xba, 0x69, 0xd2,
	0xb9, 0x6f, 0xde, 0xa1, 0x5f, 0xbe, 0x61, 0xc2, 0x99, 0x2f,
	0x5e, 0xbc, 0x65, 0xca, 0x89, 0x0f, 0x1e, 0x3c, 0x78, 0xf0,
	0xfd, 0xe7, 0xd3, 0xbb, 0x6b, 0xd6, 0xb1, 0x7f, 0xfe, 0xe1,
	0xdf, 0xa3, 0x5b, 0xb6, 0x71, 0xe2, 0xd9, 0xaf, 0x43, 0x86,
	0x11, 0x22, 0x44, 0x88, 0x0d, 0x1a, 0x34, 0x68, 0xd0, 0xbd,
	0x67, 0xce, 0x81, 0x1f, 0x3e, 0x7c, 0xf8, 0xed, 0xc7, 0x93,
	0x3b, 0x76, 0xec, 0xc5, 0x97, 0x33, 0x66, 0xcc, 0x85, 0x17,
	0x2e, 0x5c, 0xb8, 0x6d, 0xda, 0xa9, 0x4f, 0x9e, 0x21, 0x42,
	0x84, 0x15, 0x2a, 0x54, 0xa8, 0x4d, 0x9a, 0x29, 0x52, 0xa4,
	0x55, 0xaa, 0x49, 0x92, 0x39, 0x72, 0xe4, 0xd5, 0xb7, 0x73,
	0xe6, 0xd1, 0xbf, 0x63, 0xc6, 0x91, 0x3f, 0x7e, 0xfc, 0xe5,
	0xd7, 0xb3, 0x7b, 0xf6, 0xf1, 0xff, 0xe3, 0xdb, 0xab, 0x4b,
	0x96, 0x31, 0x62, 0xc4, 0x95, 0x37, 0x6e, 0xdc, 0xa5, 0x57,
	0xae, 0x41, 0x82, 0x19, 0x32, 0x64, 0xc8, 0x8d, 0x07, 0x0e,
	0x1c, 0x38, 0x70, 0xe0, 0xdd, 0xa7, 0x53, 0xa6, 0x51, 0xa2,
	0x59, 0xb2, 0x79, 0xf2, 0xf9, 0xef, 0xc3, 0x9b, 0x2b, 0x56,
	0xac, 0x45, 0x8a, 0x09, 0x12, 0x24, 0x48, 0x90, 0x3d, 0x7a,
	0xf4, 0xf5, 0xf7, 0xf3, 0xfb, 0xeb, 0xcb, 0x8b, 0x0b, 0x16,
	0x2c, 0x58, 0xb0, 0x7d, 0xfa, 0xe9, 0xcf, 0x83, 0x1b, 0x36,
	0x6c, 0xd8, 0xad, 0x47, 0x8e, 0x01
};

static const unsigned char gflog_base[] = {
	0x00, 0xff, 0x01, 0x19, 0x02, 0x32, 0x1a, 0xc6, 0x03, 0xdf,
	0x33, 0xee, 0x1b, 0x68, 0xc7, 0x4b, 0x04, 0x64, 0xe0, 0x0e,
	0x34, 0x8d, 0xef, 0x81, 0x1c, 0xc1, 0x69, 0xf8, 0xc8, 0x08,
	0x4c, 0x71, 0x05, 0x8a, 0x65, 0x2f, 0xe1, 0x24, 0x0f, 0x21,
	0x35, 0x93, 0x8e, 0xda, 0xf0, 0x12, 0x82, 0x45, 0x1d, 0xb5,
	0xc2, 0x7d, 0x6a, 0x27, 0xf9, 0xb9, 0xc9, 0x9a, 0x09, 0x78,
	0x4d, 0xe4, 0x72, 0xa6, 0x06, 0xbf, 0x8b, 0x62, 0x66, 0xdd,
	0x30, 0xfd, 0xe2, 0x98, 0x25, 0xb3, 0x10, 0x91, 0x22, 0x88,
	0x36, 0xd0, 0x94, 0xce, 0x8f, 0x96, 0xdb, 0xbd, 0xf1, 0xd2,
	0x13, 0x5c, 0x83, 0x38, 0x46, 0x40, 0x1e, 0x42, 0xb6, 0xa3,
	0xc3, 0x48, 0x7e, 0x6e, 0x6b, 0x3a, 0x28, 0x54, 0xfa, 0x85,
	0xba, 0x3d, 0xca, 0x5e, 0x9b, 0x9f, 0x0a, 0x15, 0x79, 0x2b,
	0x4e, 0xd4, 0xe5, 0xac, 0x73, 0xf3, 0xa7, 0x57, 0x07, 0x70,
	0xc0, 0xf7, 0x8c, 0x80, 0x63, 0x0d, 0x67, 0x4a, 0xde, 0xed,
	0x31, 0xc5, 0xfe, 0x18, 0xe3, 0xa5, 0x99, 0x77, 0x26, 0xb8,
	0xb4, 0x7c, 0x11, 0x44, 0x92, 0xd9, 0x23, 0x20, 0x89, 0x2e,
	0x37, 0x3f, 0xd1, 0x5b, 0x95, 0xbc, 0xcf, 0xcd, 0x90, 0x87,
	0x97, 0xb2, 0xdc, 0xfc, 0xbe, 0x61, 0xf2, 0x56, 0xd3, 0xab,
	0x14, 0x2a, 0x5d, 0x9e, 0x84, 0x3c, 0x39, 0x53, 0x47, 0x6d,
	0x41, 0xa2, 0x1f, 0x2d, 0x43, 0xd8, 0xb7, 0x7b, 0xa4, 0x76,
	0xc4, 0x17, 0x49, 0xec, 0x7f, 0x0c, 0x6f, 0xf6, 0x6c, 0xa1,
	0x3b, 0x52, 0x29, 0x9d, 0x55, 0xaa, 0xfb, 0x60, 0x86, 0xb1,
	0xbb, 0xcc, 0x3e, 0x5a, 0xcb, 0x59, 0x5f, 0xb0, 0x9c, 0xa9,
	0xa0, 0x51, 0x0b, 0xf5, 0x16, 0xeb, 0x7a, 0x75, 0x2c, 0xd7,
	0x4f, 0xae, 0xd5, 0xe9, 0xe6, 0xe7, 0xad, 0xe8, 0x74, 0xd6,
	0xf4, 0xea, 0xa8, 0x50, 0x58, 0xaf
};

void ec_init_tables(int k, int rows, unsigned char *a, unsigned char *g_tbls)
{
	int i, j;

	for (i = 0; i < rows; i++) {
		for (j = 0; j < k; j++) {
			gf_vect_mul_init(*a++, g_tbls);
			g_tbls += 32;
		}
	}
}
EXPORT_SYMBOL(ec_init_tables);

unsigned char gf_mul(unsigned char a, unsigned char b)
{
	int i;

	if ((a == 0) || (b == 0))
		return 0;

	i = gflog_base[a] + gflog_base[b];
	return gff_base[i > 254 ? i - 255 : i];
}

unsigned char gf_inv(unsigned char a)
{
	if (a == 0)
		return 0;

	return gff_base[255 - gflog_base[a]];
}

void gf_gen_cauchy1_matrix(unsigned char *a, int m, int k)
{
	int i, j;
	unsigned char *p;

	/* Identity matrix in high position */
	memset(a, 0, k * m);
	for (i = 0; i < k; i++)
		a[k * i + i] = 1;

	/* For the rest choose 1/(i + j) | i != j */
	p = &a[k * k];
	for (i = k; i < m; i++)
		for (j = 0; j < k; j++)
			*p++ = gf_inv(i ^ j);

}
EXPORT_SYMBOL(gf_gen_cauchy1_matrix);

int gf_invert_matrix(unsigned char *in_mat, unsigned char *out_mat, const int n)
{
	int i, j, k;
	unsigned char temp;

	/* Set out_mat[] to the identity matrix */
	for (i = 0; i < n * n; i++)	/* memset(out_mat, 0, n*n) */
		out_mat[i] = 0;

	for (i = 0; i < n; i++)
		out_mat[i * n + i] = 1;

	/* Inverse */
	for (i = 0; i < n; i++) {
		/* Check for 0 in pivot element */
		if (in_mat[i * n + i] == 0) {
			/* Find a row with non-zero in current column and swap */
			for (j = i + 1; j < n; j++)
				if (in_mat[j * n + i])
					break;

			if (j == n)	/* Couldn't find means it's singular */
				return -1;

			for (k = 0; k < n; k++) {	/* Swap rows i,j */
				temp = in_mat[i * n + k];
				in_mat[i * n + k] = in_mat[j * n + k];
				in_mat[j * n + k] = temp;

				temp = out_mat[i * n + k];
				out_mat[i * n + k] = out_mat[j * n + k];
				out_mat[j * n + k] = temp;
			}
		}

		temp = gf_inv(in_mat[i * n + i]);	/* 1/pivot */
		for (j = 0; j < n; j++) {	/* Scale row i by 1/pivot */
			in_mat[i * n + j] = gf_mul(in_mat[i * n + j], temp);
			out_mat[i * n + j] = gf_mul(out_mat[i * n + j], temp);
		}

		for (j = 0; j < n; j++) {
			if (j == i)
				continue;

			temp = in_mat[j * n + i];
			for (k = 0; k < n; k++) {
				out_mat[j * n + k] ^= gf_mul(temp, out_mat[i * n + k]);
				in_mat[j * n + k] ^= gf_mul(temp, in_mat[i * n + k]);
			}
		}
	}
	return 0;
}
EXPORT_SYMBOL(gf_invert_matrix);

/* Calculates const table gftbl in GF(2^8) from single input A
 * gftbl(A) = {A{00}, A{01}, A{02}, ... , A{0f} }, {A{00}, A{10}, A{20}, ... ,
 * A{f0} }
 */
void gf_vect_mul_init(unsigned char c, unsigned char *tbl)
{
	unsigned char c2 = (c << 1) ^ ((c & 0x80) ? 0x1d : 0);	/* Mult by
								 * GF{2}
								 */
	unsigned char c4 = (c2 << 1) ^ ((c2 & 0x80) ? 0x1d : 0); /* Mult by
								  * GF{2}
								  */
	unsigned char c8 = (c4 << 1) ^ ((c4 & 0x80) ? 0x1d : 0); /* Mult by
								  * GF{2}
								  */
#if BITS_PER_LONG == 64
	unsigned long long v1, v2, v4, v8, *t;
	unsigned long long v10, v20, v40, v80;
	unsigned char c17, c18, c20, c24;

	t = (unsigned long long *)tbl;

	v1 = c * 0x0100010001000100ull;
	v2 = c2 * 0x0101000001010000ull;
	v4 = c4 * 0x0101010100000000ull;
	v8 = c8 * 0x0101010101010101ull;

	v4 = v1 ^ v2 ^ v4;
	t[0] = v4;
	t[1] = v8 ^ v4;

	c17 = (c8 << 1) ^ ((c8 & 0x80) ? 0x1d : 0);	//Mult by GF{2}
	c18 = (c17 << 1) ^ ((c17 & 0x80) ? 0x1d : 0);	//Mult by GF{2}
	c20 = (c18 << 1) ^ ((c18 & 0x80) ? 0x1d : 0);	//Mult by GF{2}
	c24 = (c20 << 1) ^ ((c20 & 0x80) ? 0x1d : 0);	//Mult by GF{2}

	v10 = c17 * 0x0100010001000100ull;
	v20 = c18 * 0x0101000001010000ull;
	v40 = c20 * 0x0101010100000000ull;
	v80 = c24 * 0x0101010101010101ull;

	v40 = v10 ^ v20 ^ v40;
	t[2] = v40;
	t[3] = v80 ^ v40;

#else /* 32-bit or other */
	unsigned char c3, c5, c6, c7, c9, c10, c11, c12, c13, c14, c15;
	unsigned char c17, c18, c19, c20, c21, c22, c23, c24, c25, c26;
	unsigned char c27, c28, c29, c30, c31;

	c3 = c2 ^ c;
	c5 = c4 ^ c;
	c6 = c4 ^ c2;
	c7 = c4 ^ c3;

	c9 = c8 ^ c;
	c10 = c8 ^ c2;
	c11 = c8 ^ c3;
	c12 = c8 ^ c4;
	c13 = c8 ^ c5;
	c14 = c8 ^ c6;
	c15 = c8 ^ c7;

	tbl[0] = 0;
	tbl[1] = c;
	tbl[2] = c2;
	tbl[3] = c3;
	tbl[4] = c4;
	tbl[5] = c5;
	tbl[6] = c6;
	tbl[7] = c7;
	tbl[8] = c8;
	tbl[9] = c9;
	tbl[10] = c10;
	tbl[11] = c11;
	tbl[12] = c12;
	tbl[13] = c13;
	tbl[14] = c14;
	tbl[15] = c15;

	c17 = (c8 << 1) ^ ((c8 & 0x80) ? 0x1d : 0);	/* Mult by GF{2} */
	c18 = (c17 << 1) ^ ((c17 & 0x80) ? 0x1d : 0);	/* Mult by GF{2} */
	c19 = c18 ^ c17;
	c20 = (c18 << 1) ^ ((c18 & 0x80) ? 0x1d : 0);	/* Mult by GF{2} */
	c21 = c20 ^ c17;
	c22 = c20 ^ c18;
	c23 = c20 ^ c19;
	c24 = (c20 << 1) ^ ((c20 & 0x80) ? 0x1d : 0);	/* Mult by GF{2} */
	c25 = c24 ^ c17;
	c26 = c24 ^ c18;
	c27 = c24 ^ c19;
	c28 = c24 ^ c20;
	c29 = c24 ^ c21;
	c30 = c24 ^ c22;
	c31 = c24 ^ c23;

	tbl[16] = 0;
	tbl[17] = c17;
	tbl[18] = c18;
	tbl[19] = c19;
	tbl[20] = c20;
	tbl[21] = c21;
	tbl[22] = c22;
	tbl[23] = c23;
	tbl[24] = c24;
	tbl[25] = c25;
	tbl[26] = c26;
	tbl[27] = c27;
	tbl[28] = c28;
	tbl[29] = c29;
	tbl[30] = c30;
	tbl[31] = c31;

#endif /* BITS_PER_LONG == 64 */
}

void ec_encode_data(int len, int srcs, int dests, unsigned char *v,
		    unsigned char **src, unsigned char **dest)
{
	int i, j, l;
	unsigned char s;

	for (l = 0; l < dests; l++) {
		for (i = 0; i < len; i++) {
			s = 0;
			for (j = 0; j < srcs; j++)
				s ^= gf_mul(src[j][i], v[j * 32 + l * srcs * 32 + 1]);

			dest[l][i] = s;
		}
	}
}
EXPORT_SYMBOL(ec_encode_data);

static int __init ec_init(void)
{
	return 0;
}

static void __exit ec_exit(void)
{
}

MODULE_AUTHOR("Intel Corporation");
MODULE_DESCRIPTION("M to N erasure code handling");
MODULE_VERSION("1.0.0");
MODULE_LICENSE("Dual BSD/GPL");

module_init(ec_init);
module_exit(ec_exit);