src/libs/ck-libs/metis/GKlib/b64.c

   1 /*!
   2 \file  b64.c
   3 \brief This file contains some simple 8bit-to-6bit encoding/deconding routines
   4
   5 Most of these routines are outdated and should be converted using glibc's equivalent
   6 routines.
   7
   8 \date   Started 2/22/05
   9 \author George
  10 \version\verbatim $Id: b64.c 10711 2011-08-31 22:23:04Z karypis $ \endverbatim
  11
  12 \verbatim
  13 $Copyright$
  14 $License$
  15 \endverbatim
  16
  17 */
  18
  19
  20 #include "GKlib.h"
  21
  22 #define B64OFFSET       48      /* This is the '0' number */
  23
  24
  25 /******************************************************************************
  26 * Encode 3 '8-bit' binary bytes as 4 '6-bit' characters
  27 *******************************************************************************/
  28 void encodeblock(unsigned char *in, unsigned char *out)
  29 {
  30   out[0] = (in[0] >> 2);
  31   out[1] = (((in[0] & 0x03) << 4) | (in[1] >> 4));
  32   out[2] = (((in[1] & 0x0f) << 2) | (in[2] >> 6));
  33   out[3] = (in[2] & 0x3f);
  34
  35   out[0] += B64OFFSET;
  36   out[1] += B64OFFSET;
  37   out[2] += B64OFFSET;
  38   out[3] += B64OFFSET;
  39
  40 //  printf("%c %c %c %c %2x %2x %2x %2x %2x %2x %2x\n", out[0], out[1], out[2], out[3], out[0], out[1], out[2], out[3], in[0], in[1], in[2]);
  41 }
  42
  43 /******************************************************************************
  44 * Decode 4 '6-bit' characters into 3 '8-bit' binary bytes
  45 *******************************************************************************/
  46 void decodeblock(unsigned char *in, unsigned char *out)
  47 {
  48   in[0] -= B64OFFSET;
  49   in[1] -= B64OFFSET;
  50   in[2] -= B64OFFSET;
  51   in[3] -= B64OFFSET;
  52
  53   out[0] = (in[0] << 2 | in[1] >> 4);
  54   out[1] = (in[1] << 4 | in[2] >> 2);
  55   out[2] = (in[2] << 6 | in[3]);
  56 }
  57
  58
  59 /******************************************************************************
  60 * This function encodes an input array of bytes into a base64 encoding. Memory
  61 * for the output array is assumed to have been allocated by the calling program
  62 * and be sufficiently large. The output string is NULL terminated.
  63 *******************************************************************************/
  64 void GKEncodeBase64(int nbytes, unsigned char *inbuffer, unsigned char *outbuffer)
  65 {
  66   int i, j;
  67
  68   if (nbytes%3 != 0)
  69     gk_errexit(SIGERR, "GKEncodeBase64: Input buffer size should be a multiple of 3! (%d)\n", nbytes);
  70
  71   for (j=0, i=0; i<nbytes; i+=3, j+=4)
  72     encodeblock(inbuffer+i, outbuffer+j);
  73
  74 //printf("%d %d\n", nbytes, j);
  75   outbuffer[j] = '\0';
  76 }
  77
  78
  79
  80 /******************************************************************************
  81 * This function decodes an input array of base64 characters into their actual
  82 * 8-bit codes. Memory * for the output array is assumed to have been allocated
  83 * by the calling program and be sufficiently large. The padding is discarded.
  84 *******************************************************************************/
  85 void GKDecodeBase64(int nbytes, unsigned char *inbuffer, unsigned char *outbuffer)
  86 {
  87   int i, j;
  88
  89   if (nbytes%4 != 0)
  90     gk_errexit(SIGERR, "GKDecodeBase64: Input buffer size should be a multiple of 4! (%d)\n", nbytes);
  91
  92   for (j=0, i=0; i<nbytes; i+=4, j+=3)
  93     decodeblock(inbuffer+i, outbuffer+j);
  94 }
  95