/* Examples/jerasure_05.c
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.

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   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
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 */
    

/*
	revised by S. Simmerman
	2/25/08  
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "jerasure.h"

#define talloc(type, num) (type *) malloc(sizeof(type)*(num))

usage(char *s)
{
  fprintf(stderr, "usage: jerasure_05 k m w size - Does a simple Reed-Solomon coding example in GF(2^w).\n");
  fprintf(stderr, "       \n");
  fprintf(stderr, "       k+m must be <= 2^w.  w can be 8, 16 or 32.\n");
  fprintf(stderr, "       It sets up a Cauchy distribution matrix and encodes\n");
  fprintf(stderr, "       k devices of size bytes with it.  Then it decodes.\n", sizeof(long));
  fprintf(stderr, "       After that, it decodes device 0 by using jerasure_make_decoding_matrix()\n");
  fprintf(stderr, "       and jerasure_matrix_dotprod().\n");
  fprintf(stderr, "       \n");
  fprintf(stderr, "This demonstrates: jerasure_matrix_encode()\n");
  fprintf(stderr, "                   jerasure_matrix_decode()\n");
  fprintf(stderr, "                   jerasure_print_matrix()\n");
  fprintf(stderr, "                   jerasure_make_decoding_matrix()\n");
  fprintf(stderr, "                   jerasure_matrix_dotprod()\n");
  if (s != NULL) fprintf(stderr, "\n%s\n\n", s);
  exit(1);
}

static void print_data_and_coding(int k, int m, int w, int size, 
		char **data, char **coding) 
{
  int i, j, x;
  int n, sp;
  long l;

  if(k > m) n = k;
  else n = m;
  sp = size * 2 + size/(w/8) + 8;

  printf("%-*sCoding\n", sp, "Data");
  for(i = 0; i < n; i++) {
	  if(i < k) {
		  printf("D%-2d:", i);
		  for(j=0;j< size; j+=(w/8)) { 
			  printf(" ");
			  for(x=0;x < w/8;x++){
				printf("%02x", (unsigned char)data[i][j+x]);
			  }
		  }
		  printf("    ");
	  }
	  else printf("%*s", sp, "");
	  if(i < m) {
		  printf("C%-2d:", i);
		  for(j=0;j< size; j+=(w/8)) { 
			  printf(" ");
			  for(x=0;x < w/8;x++){
				printf("%02x", (unsigned char)coding[i][j+x]);
			  }
		  }
	  }
	  printf("\n");
  }
	printf("\n");
}

int main(int argc, char **argv)
{
  long l;
  int k, m, w, size;
  int i, j;
  int *matrix;
  char **data, **coding;
  int *erasures, *erased;
  int *decoding_matrix, *dm_ids;
  
  if (argc != 5) usage(NULL);
  if (sscanf(argv[1], "%d", &k) == 0 || k <= 0) usage("Bad k");
  if (sscanf(argv[2], "%d", &m) == 0 || m <= 0) usage("Bad m");
  if (sscanf(argv[3], "%d", &w) == 0 || (w != 8 && w != 16 && w != 32))
		  usage("Bad w");
  if (w < 32 && k + m > (1 << w)) usage("k + m must be <= 2 ^ w");
  if (sscanf(argv[4], "%d", &size) == 0 || size % sizeof(long) != 0) 
		usage("size must be multiple of sizeof(long)");

  matrix = talloc(int, m*k);
  for (i = 0; i < m; i++) {
    for (j = 0; j < k; j++) {
      matrix[i*k+j] = galois_single_divide(1, i ^ (m + j), w);
    }
  }

  printf("The Coding Matrix (the last m rows of the Distribution Matrix):\n\n");
  jerasure_print_matrix(matrix, m, k, w);
  printf("\n");

  srand48(0);
  data = talloc(char *, k);
  for (i = 0; i < k; i++) {
    data[i] = talloc(char, size);
	for(j = 0; j < size; j+=sizeof(long)) {
		l = lrand48();
		memcpy(data[i] + j, &l, sizeof(long));
	}
  }

  coding = talloc(char *, m);
  for (i = 0; i < m; i++) {
    coding[i] = talloc(char, size);
  }

  jerasure_matrix_encode(k, m, w, matrix, data, coding, size);
  
  printf("Encoding Complete:\n\n");
  print_data_and_coding(k, m, w, size, data, coding);

  erasures = talloc(int, (m+1));
  erased = talloc(int, (k+m));
  for (i = 0; i < m+k; i++) erased[i] = 0;
  l = 0;
  for (i = 0; i < m; ) {
    erasures[i] = lrand48()%(k+m);
    if (erased[erasures[i]] == 0) {
      erased[erasures[i]] = 1;
	  
      bzero((erasures[i] < k) ? data[erasures[i]] : coding[erasures[i]-k], size);
      i++;
    }
  }
  erasures[i] = -1;

  printf("Erased %d random devices:\n\n", m);
  print_data_and_coding(k, m, w, size, data, coding);
  
  i = jerasure_matrix_decode(k, m, w, matrix, 0, erasures, data, coding, size);

  printf("State of the system after decoding:\n\n");
  print_data_and_coding(k, m, w, size, data, coding);
  
  decoding_matrix = talloc(int, k*k);
  dm_ids = talloc(int, k);

  for (i = 0; i < m; i++) erased[i] = 1;
  for (; i < k+m; i++) erased[i] = 0;

  jerasure_make_decoding_matrix(k, m, w, matrix, erased, decoding_matrix, dm_ids);

  printf("Suppose we erase the first %d devices.  Here is the decoding matrix:\n\n", m);
  jerasure_print_matrix(decoding_matrix, k, k, w);
  printf("\n");
  printf("And dm_ids:\n\n");
  jerasure_print_matrix(dm_ids, 1, k, w);

  bzero(data[0], size);
  jerasure_matrix_dotprod(k, w, decoding_matrix, dm_ids, 0, data, coding, size);

  printf("\nAfter calling jerasure_matrix_dotprod, we calculate the value of device #0 to be:\n\n");
  printf("D0 :");
  for(i=0;i< size; i+=(w/8)) {
	  printf(" ");
	  for(j=0;j < w/8;j++){
		printf("%02x", (unsigned char)data[0][i+j]);
	  }
  }
  printf("\n\n");

  return 0;
}