galois.h 4.73 KB
/* Galois.h
 * James S. Plank

Jerasure - A C/C++ Library for a Variety of Reed-Solomon and RAID-6 Erasure Coding Techniques

Revision 1.2A
May 24, 2011

James S. Plank
Department of Electrical Engineering and Computer Science
University of Tennessee
Knoxville, TN 37996
plank@cs.utk.edu

Copyright (c) 2011, James S. Plank
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 the University of Tennessee 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
HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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 */

#ifndef _GALOIS_H
#define _GALOIS_H

#include <stdio.h>
#include <stdlib.h>
#include <gf_complete.h>

extern void galois_change_technique(gf_t *gf, int w);

extern int galois_single_multiply(int a, int b, int w);
extern int galois_single_divide(int a, int b, int w);
extern int galois_inverse(int x, int w);

void galois_region_xor(           char *r1,         /* Region 1 */
                                  char *r2,         /* Region 2 */
                                  char *r3,         /* Sum region (r3 = r1 ^ r2) -- can be r1 or r2 */
                                  int nbytes);      /* Number of bytes in region */

/* These multiply regions in w=8, w=16 and w=32.  They are much faster
   than calling galois_single_multiply.  The regions must be long word aligned. */

void galois_w08_region_multiply(char *region,       /* Region to multiply */
                                  int multby,       /* Number to multiply by */
                                  int nbytes,       /* Number of bytes in region */
                                  char *r2,         /* If r2 != NULL, products go here.  
                                                       Otherwise region is overwritten */
                                  int add);         /* If (r2 != NULL && add) the produce is XOR'd with r2 */

void galois_w16_region_multiply(char *region,       /* Region to multiply */
                                  int multby,       /* Number to multiply by */
                                  int nbytes,       /* Number of bytes in region */
                                  char *r2,         /* If r2 != NULL, products go here.  
                                                       Otherwise region is overwritten */
                                  int add);         /* If (r2 != NULL && add) the produce is XOR'd with r2 */

void galois_w32_region_multiply(char *region,       /* Region to multiply */
                                  int multby,       /* Number to multiply by */
                                  int nbytes,       /* Number of bytes in region */
                                  char *r2,         /* If r2 != NULL, products go here.  
                                                       Otherwise region is overwritten */
                                  int add);         /* If (r2 != NULL && add) the produce is XOR'd with r2 */

int galois_init_base_field(int w,
                           int mult_type,
                           int region_type,
                           int divide_type,
                           uint64_t prim_poly,
                           int arg1,
                           int arg2);

int galois_init_composite_field(int w,
                                int region_type,
                                int divide_type,
                                uint64_t prim_poly,
                                int arg1,
                                int arg2,
                                gf_t* base_gf);

gf_t * galois_get_field_ptr(int w);


#endif