#include	<stdio.h>
#include	<string.h>
#include	<malloc.h>

static unsigned char *base64 = (unsigned char *)"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

static void enclode_char(unsigned long bb, int srclen, unsigned char *dest, int j)
{
	int					x, i, base;

	/* 最終位置の計算 */
	for ( i = srclen; i < 2; i++ ) 
		bb <<= 8;

	/* BASE64変換 */
	for ( base = 18, x = 0; x < srclen + 2; x++, base -= 6) {
		dest[j++] = base64[ (unsigned long)((bb>>base) & 0x3F) ];
	}

	/* 端数の判断 */
	for ( i = x; i < 4; i++ ) {
		dest[j++] = (unsigned char)'=';		/* 端数 */
	}
	
}

static void enclode(const unsigned char *src, unsigned char *dest)
{
	unsigned	char	*p = (char *)src;
	unsigned	long	bb = (unsigned long)0;
	int					i = 0, j = 0;

	while (*p)
	{
		bb <<= 8;
		bb |= (unsigned long)*p;

		/* 24bit単位に編集 */
		if (i == 2) {
			enclode_char(bb, i, dest, j);

			j = j + 4;
			i = 0;
			bb = 0;
		} else
			i++;

		p++;
	}

	/* 24bitに満たない場合 */
	if (i)
		enclode_char(bb, i - 1, dest, j);

}

main()
{
	char	*src = "Hello";
	char	dest[100];

	memset(dest, 0, sizeof(dest));

	/**/
	enclode(src, dest);

	/**/
	printf("dest = %s\n", dest);
}