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[base64] Add base64 encoding functions
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Michael Brown committed Feb 13, 2009
1 parent 4e6b62c commit d900ae0
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66 changes: 66 additions & 0 deletions src/core/base64.c
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/*
* Copyright (C) 2009 Michael Brown <mbrown@fensystems.co.uk>.
*
* 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 of the
* License, or 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 this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include <stdint.h>
#include <string.h>
#include <assert.h>
#include <gpxe/base64.h>

/** @file
*
* Base64 encoding
*
*/

static const char base64[64] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

/**
* Base64-encode a string
*
* @v raw Raw string
* @v encoded Buffer for encoded string
*
* The buffer must be the correct length for the encoded string. Use
* something like
*
* char buf[ base64_encoded_len ( strlen ( raw ) ) + 1 ];
*
* (the +1 is for the terminating NUL) to provide a buffer of the
* correct size.
*/
void base64_encode ( const char *raw, char *encoded ) {
const uint8_t *raw_bytes = ( ( const uint8_t * ) raw );
uint8_t *encoded_bytes = ( ( uint8_t * ) encoded );
size_t raw_bit_len = ( 8 * strlen ( raw ) );
unsigned int bit;
unsigned int tmp;

for ( bit = 0 ; bit < raw_bit_len ; bit += 6 ) {
tmp = ( ( raw_bytes[ bit / 8 ] << ( bit % 8 ) ) |
( raw_bytes[ bit / 8 + 1 ] >> ( 8 - ( bit % 8 ) ) ) );
tmp = ( ( tmp >> 2 ) & 0x3f );
*(encoded_bytes++) = base64[tmp];
}
for ( ; ( bit % 8 ) != 0 ; bit += 6 )
*(encoded_bytes++) = '=';
*(encoded_bytes++) = '\0';

DBG ( "Base64-encoded \"%s\" as \"%s\"\n", raw, encoded );
assert ( strlen ( encoded ) == base64_encoded_len ( strlen ( raw ) ) );
}
24 changes: 24 additions & 0 deletions src/include/gpxe/base64.h
@@ -0,0 +1,24 @@
#ifndef _GPXE_BASE64_H
#define _GPXE_BASE64_H

/** @file
*
* Base64 encoding
*
*/

#include <stdint.h>

/**
* Calculate length of base64-encoded string
*
* @v raw_len Raw string length (excluding NUL)
* @ret encoded_len Encoded string length (excluding NUL)
*/
static inline size_t base64_encoded_len ( size_t raw_len ) {
return ( ( ( raw_len + 3 - 1 ) / 3 ) * 4 );
}

extern void base64_encode ( const char *raw, char *encoded );

#endif /* _GPXE_BASE64_H */

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