/* 
** Author:  Daniel Stenberg <Daniel.Stenberg@haxx.nu>
** Version: 0.1
**
** This is a Base64 encoder as defined in RFC 2045. If the output is gonna be
** used in a mail body: "The encoded output stream must be represented in
** lines of no more than 76 characters each."
**
* CHANGES by Daniel Stenberg. May 11, 1998:
*
* - Encoded strings that ended with more than one = caused the decode 
*   function+ to generate 3 extra zero bytes at the end of the output.
*/

#include "main.h"

void base64Decode(char *intext, char *out, int *length)
{
    unsigned char ibuf[4];
    unsigned char obuf[3];
    char ignore;
    char endtext=FALSE;
    char ch;
    int index=0;
    *length = 0;
  
    memset(ibuf, 0, sizeof(ibuf));

    while (*intext) {
        ch = *intext;
    
        ignore = FALSE;
        if ((ch >= 'A') && (ch <= 'Z'))
            ch = ch - 'A';
        else if ((ch >= 'a') && (ch <= 'z'))
            ch = ch - 'a' + 26;
        else if ((ch >= '0') && (ch <= '9'))
            ch = ch - '0' + 52;
        else if (ch == '+')
            ch = 62;
        else if (ch == '=') { /* end of text */
            if (endtext)
                break;
            endtext = TRUE;
            index--;
            if (index < 0)
                index = 3;
        }
        else if (ch == '/')
            ch = 63;
        else if (endtext)
            break;
        else
            ignore = TRUE; 
        
        if (!ignore) {
            if (!endtext) {
               ibuf[index] = ch;
    
               index ++;
               index &= 3; /* use bit arithmetic instead of remainder */
            }
            if ((0 == index) || endtext) {
    
                obuf [0] = (ibuf [0] << 2) | ((ibuf [1] & 0x30) >> 4);
                obuf [1] = ((ibuf [1] & 0x0F) << 4) | ((ibuf [2] & 0x3C) >> 2);
                obuf [2] = ((ibuf [2] & 0x03) << 6) | (ibuf [3] & 0x3F);
    
                switch(index) {
                    case 1:
                      sprintf(out, "%c", obuf[0]);
                      out++;
                      (*length)++;
                      break;
                    case 2:
                      sprintf(out, "%c%c", obuf[0], obuf[1]);
                      out+=2;
                      (*length)+=2;
                      break;
                    default:
                      sprintf(out, "%c%c%c", obuf[0], obuf[1], obuf[2]);
                      out+=3;
                      (*length)+=3;
                      break;
                }
                memset(ibuf, 0, sizeof(ibuf));
            }      
        }
        intext++;
    }
    *out=0;
}