base64.c.svn-base

psp播放器PPA源码,在MSYS/CYGWIN环境下编译（GNU-C）

/* 
 *	Copyright (C) 2006 cooleyes
 *	[e-mail] 
 *
 *  This Program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2, or (at your option)
 *  any later version.
 *   
 *  This Program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 *  GNU General Public License for more details.
 *   
 *  You should have received a copy of the GNU General Public License
 *  along with GNU Make; see the file COPYING.  If not, write to
 *  the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. 
 *  http://www.gnu.org/copyleft/gpl.html
 *
 */
 
#include "base64.h"

static char *base64_encoding = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

char get_base64_value(char ch) {
	if ((ch >= 'A') && (ch <= 'Z')) 
		return ch - 'A'; 
	if ((ch >= 'a') && (ch <= 'z')) 
		return ch - 'a' + 26; 
	if ((ch >= '0') && (ch <= '9')) 
		return ch - '0' + 52; 
	switch (ch) { 
		case '+': 
			return 62; 
		case '/': 
			return 63; 
		case '=': /* base64 padding */ 
			return 0; 
		default: 
			return 0; 
	} 
}


int base64encode(char * buffer, const unsigned char * src, int len ) { 
	int buflen = 0; 

	while(len>0){
		*buffer++ = base64_encoding[ (src[0] >> 2 ) & 0x3f];
		if(len>2){
			*buffer++ = base64_encoding[((src[0] & 3) << 4) | (src[1] >> 4)];
			*buffer++ = base64_encoding[((src[1] & 0xF) << 2) | (src[2] >> 6)];
			*buffer++ = base64_encoding[src[2] & 0x3F];
		}
		else{
			switch(len){
				case 1:
					*buffer++ = base64_encoding[(src[0] & 3) << 4 ];
					*buffer++ = '=';
					*buffer++ = '=';
					break;
				case 2: 
					*buffer++ = base64_encoding[((src[0] & 3) << 4) | (src[1] >> 4)]; 
					*buffer++ = base64_encoding[((src[1] & 0x0F) << 2) | (src[2] >> 6)]; 
					*buffer++ = '='; 
					break; 
			} 
		} 

		src +=3; 
		len -=3; 
		buflen +=4; 
	} 

	*buffer = 0; 
	return buflen; 
} 

int base64decode( unsigned char * buffer, const char * src, int len ){
	if(len%4)
		return -1;
	unsigned char chunk[4];
	int parsenum=0;

	while(len>0){
		chunk[0] = get_base64_value(src[0]); 
		chunk[1] = get_base64_value(src[1]); 
		chunk[2] = get_base64_value(src[2]); 
		chunk[3] = get_base64_value(src[3]); 

		*buffer++ = (chunk[0] << 2) | (chunk[1] >> 4); 
		*buffer++ = (chunk[1] << 4) | (chunk[2] >> 2); 
		*buffer++ = (chunk[2] << 6) | (chunk[3]);

		src+=4;
		len-=4;
		parsenum+=3;
	}

	return parsenum;
}