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mkp224o/base64_from.c

94 lines
3.1 KiB

#include <stddef.h>
#include <stdint.h>
#include "types.h"
#include "base64.h"
static const u8 base64f[256] = {
//00 01 02 03 04 05 06 07
//08 09 0A 0B 0C 0D 0E 0F
// 0x00..0x3F
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 0x00
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 0x08
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 0x10
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 0x18
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 0x20
0xFF, 0xFF, 0xFF, 0x3E, 0xFF, 0xFF, 0xFF, 0x3F, // 0x28
0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x3B, // 0x30
0x3C, 0x3D, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 0x38
// 0x40..0x7F
0xFF, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, // 0x40
0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, // 0x48
0x0F, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, // 0x50
0x17, 0x18, 0x19, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 0x58
0xFF, 0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20, // 0x60
0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, // 0x68
0x29, 0x2A, 0x2B, 0x2C, 0x2D, 0x2E, 0x2F, 0x30, // 0x70
0x31, 0x32, 0x33, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 0x78
// 0x80..0xBF
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
// 0xC0..0xFF
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
};
size_t base64_from(u8 *dst,const char *src,size_t srclen)
{
if (srclen % 4) {
return -1;
} else if (!srclen) {
return 0;
}
size_t dstlen = BASE64_FROM_LEN(srclen);
dstlen -= (src[srclen - 1] == '=');
dstlen -= (src[srclen - 2] == '=');
for (size_t i = 0, j = 0; i < srclen;) {
u32 sixbits[4];
sixbits[0] = base64f[(unsigned char)src[i++]];
sixbits[1] = base64f[(unsigned char)src[i++]];
sixbits[2] = (src[i] == '=' ? (0 & i++) : base64f[(unsigned char)src[i++]]);
sixbits[3] = (src[i] == '=' ? (0 & i++) : base64f[(unsigned char)src[i++]]);
u32 threebytes = 0
| (sixbits[0] << (3 * 6))
| (sixbits[1] << (2 * 6))
| (sixbits[2] << (1 * 6))
| (sixbits[3] << (0 * 6));
if (j < dstlen) dst[j++] = (threebytes >> (2 * 8));
if (j < dstlen) dst[j++] = (threebytes >> (1 * 8)) & 0xff;
if (j < dstlen) dst[j++] = (threebytes >> (0 * 8)) & 0xff;
}
return dstlen;
}
int base64_valid(const char *src,size_t *count)
{
const char *p;
for (p = src;base64f[(u8)*p] != 0xFF;++p)
;
for (;((size_t) (p - src)) % 4 != 0 && *p == '=';++p)
;
if (count)
*count = (size_t) (p - src);
return !*p && ((size_t) (p - src)) % 4 == 0;
}