#include "precompile.h"
#include "base64.h"

/* aaaack but it's fast and const should make it shared text page. */
static const unsigned char pr2six[256] =
{
	/* ASCII table */
	64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
	64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
	64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 62, 64, 64, 64, 63,
	52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 64, 64, 64, 64, 64, 64,
	64,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14,
	15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 64, 64, 64, 64, 64,
	64, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
	41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 64, 64, 64, 64, 64,
	64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
	64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
	64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
	64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
	64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
	64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
	64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
	64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64
};

static const char basis_64[] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

TOOLKIT_API int base64_encode(char * coded_dst, const char *plain_src, int len_plain_src)
{
	int i;
	char *p;

	p = coded_dst;
	for (i = 0; i < len_plain_src - 2; i += 3) {
		*p++ = basis_64[(plain_src[i] >> 2) & 0x3F];
		*p++ = basis_64[((plain_src[i] & 0x3) << 4) |
			((int) (plain_src[i + 1] & 0xF0) >> 4)];
		*p++ = basis_64[((plain_src[i + 1] & 0xF) << 2) |
			((int) (plain_src[i + 2] & 0xC0) >> 6)];
		*p++ = basis_64[plain_src[i + 2] & 0x3F];
	}
	if (i < len_plain_src) {
		*p++ = basis_64[(plain_src[i] >> 2) & 0x3F];
		if (i == (len_plain_src - 1)) {
			*p++ = basis_64[((plain_src[i] & 0x3) << 4)];
			*p++ = '=';
		}
		else {
			*p++ = basis_64[((plain_src[i] & 0x3) << 4) |
				((int) (plain_src[i + 1] & 0xF0) >> 4)];
			*p++ = basis_64[((plain_src[i + 1] & 0xF) << 2)];
		}
		*p++ = '=';
	}

	*p++ = '\0';
	return (int)(p - coded_dst);
}

TOOLKIT_API int base64_decode_len(const char * bufcoded)
{
	int nbytesdecoded;
	register const unsigned char *bufin;
	register int nprbytes;

	bufin = (const unsigned char *) bufcoded;
	while (pr2six[*(bufin++)] <= 63);

	nprbytes = (bufin - (const unsigned char *) bufcoded) - 1;
	nbytesdecoded = (((int)nprbytes + 3) / 4) * 3;

	return nbytesdecoded + 1;
}

TOOLKIT_API int base64_decode(char * bufplain, const char *bufcoded)
{
	int nbytesdecoded;
	register const unsigned char *bufin;
	register unsigned char *bufout;
	register int nprbytes;

	bufin = (const unsigned char *) bufcoded;
	while (pr2six[*(bufin++)] <= 63);
	nprbytes = (bufin - (const unsigned char *) bufcoded) - 1;
	nbytesdecoded = (((int)nprbytes + 3) / 4) * 3;

	bufout = (unsigned char *) bufplain;
	bufin = (const unsigned char *) bufcoded;

	while (nprbytes > 4) {
		*(bufout++) =
			(unsigned char) (pr2six[*bufin] << 2 | pr2six[bufin[1]] >> 4);
		*(bufout++) =
			(unsigned char) (pr2six[bufin[1]] << 4 | pr2six[bufin[2]] >> 2);
		*(bufout++) =
			(unsigned char) (pr2six[bufin[2]] << 6 | pr2six[bufin[3]]);
		bufin += 4;
		nprbytes -= 4;
	}

	/* Note: (nprbytes == 1) would be an error, so just ingore that case */
	if (nprbytes > 1) {
		*(bufout++) =
			(unsigned char) (pr2six[*bufin] << 2 | pr2six[bufin[1]] >> 4);
	}
	if (nprbytes > 2) {
		*(bufout++) =
			(unsigned char) (pr2six[bufin[1]] << 4 | pr2six[bufin[2]] >> 2);
	}
	if (nprbytes > 3) {
		*(bufout++) =
			(unsigned char) (pr2six[bufin[2]] << 6 | pr2six[bufin[3]]);
	}

	nbytesdecoded -= (4 - (int)nprbytes) & 3;

	*(bufout++) = '\0';

	return nbytesdecoded + 1;
}