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// SPDX-License-Identifier: GPL-2.0+ OR Apache-2.0
#include "liberofs_base64.h"
#include <string.h>
static const char lookup_table[65] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
int erofs_base64_encode(const u8 *src, int srclen, char *dst)
{
u32 ac = 0;
int bits = 0;
int i;
char *cp = dst;
for (i = 0; i < srclen; i++) {
ac = (ac << 8) | src[i];
bits += 8;
do {
bits -= 6;
*cp++ = lookup_table[(ac >> bits) & 0x3f];
} while (bits >= 6);
}
if (bits) {
*cp++ = lookup_table[(ac << (6 - bits)) & 0x3f];
bits -= 6;
}
while (bits < 0) {
*cp++ = '=';
bits += 2;
}
return cp - dst;
}
int erofs_base64_decode(const char *src, int len, u8 *dst)
{
int i, bits = 0, ac = 0;
const char *p;
u8 *cp = dst;
bool padding = false;
if(len && !(len % 4)) {
/* Check for and ignore any end padding */
if (src[len - 1] == '=')
len -= 1 + (len >= 2 && src[len - 2] == '=');
padding = true;
}
for (i = 0; i < len; i++) {
p = strchr(lookup_table, src[i]);
if (!p || !src[i])
return -2;
ac = (ac << 6 | (p - lookup_table));
bits += 6;
if (bits >= 8) {
bits -= 8;
*cp++ = ac >> bits;
}
}
ac &= BIT(bits) - 1;
if (ac) {
if (padding || ac > 0xff)
return -1;
else
*cp++ = ac;
}
return cp - dst;
}
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