#include <stdlib.h>
#include <stdio.h>

#define g_malloc malloc
#define g_realloc realloc
typedef long gint32;

char alphabet[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz" "0123456789+/";


char *tobase64(const char *text)
{
	char *out = NULL;
	const char *c;
	unsigned int tmp = 0;
	int len = 0, n = 0;

	c = text;

	while (*c) {
		tmp = tmp << 8;
		tmp += *c;
		n++;

		if (n == 3) {
			out = g_realloc(out, len + 4);
			out[len] = alphabet[(tmp >> 18) & 0x3f];
			out[len + 1] = alphabet[(tmp >> 12) & 0x3f];
			out[len + 2] = alphabet[(tmp >> 6) & 0x3f];
			out[len + 3] = alphabet[tmp & 0x3f];
			len += 4;
			tmp = 0;
			n = 0;
		}
		c++;
	}
	switch (n) {

	case 2:
		tmp <<= 8;
		out = g_realloc(out, len + 5);
		out[len] = alphabet[(tmp >> 18) & 0x3f];
		out[len + 1] = alphabet[(tmp >> 12) & 0x3f];
		out[len + 2] = alphabet[(tmp >> 6) & 0x3f];
		out[len + 3] = '=';
		out[len + 4] = 0;
		break;
	case 1:
		tmp <<= 16;
		out = g_realloc(out, len + 5);
		out[len] = alphabet[(tmp >> 18) & 0x3f];
		out[len + 1] = alphabet[(tmp >> 12) & 0x3f];
		out[len + 2] = '=';
		out[len + 3] = '=';
		out[len + 4] = 0;
		break;
	case 0:
		out = g_realloc(out, len + 1);
		out[len] = 0;
		break;
	}
	return out;
}


void frombase64(const char *text, char **data, int *size)
{
	char *out = NULL;
	char tmp = 0;
	const char *c;
	gint32 tmp2 = 0;
	int len = 0, n = 0;

	if (!text || !data)
		return;

	c = text;

	while (*c) {
		if (*c >= 'A' && *c <= 'Z') {
			tmp = *c - 'A';
		} else if (*c >= 'a' && *c <= 'z') {
			tmp = 26 + (*c - 'a');
		} else if (*c >= '0' && *c <= 57) {
			tmp = 52 + (*c - '0');
		} else if (*c == '+') {
			tmp = 62;
		} else if (*c == '/') {
			tmp = 63;
		} else if (*c == '=') {
			if (n == 3) {
				out = g_realloc(out, len + 2);
				out[len] = (char)(tmp2 >> 10) & 0xff;
				len++;
				out[len] = (char)(tmp2 >> 2) & 0xff;
				len++;
			} else if (n == 2) {
				out = g_realloc(out, len + 1);
				out[len] = (char)(tmp2 >> 4) & 0xff;
				len++;
			}
			break;
		}
		tmp2 = ((tmp2 << 6) | (tmp & 0xff));
		n++;
		if (n == 4) {
			out = g_realloc(out, len + 3);
			out[len] = (char)((tmp2 >> 16) & 0xff);
			len++;
			out[len] = (char)((tmp2 >> 8) & 0xff);
			len++;
			out[len] = (char)(tmp2 & 0xff);
			len++;
			tmp2 = 0;
			n = 0;
		}
		c++;
	}

	out = g_realloc(out, len + 1);
	out[len] = 0;

	*data = out;
	if (size)
		*size = len;
}

int main(int argc, char **argv)
{
	char *data;
	int len;
	FILE *f;

	if (argc != 3)
		return 1;

	switch (argv[1][0]) {
		case 'e':
			printf("%s\n", tobase64(argv[2]));
			break;
		case 'd':
			frombase64(argv[2], &data, &len);
			f = fopen("output", "w");
			fwrite(data, 1, len, f);
			fclose(f);
			break;
	}

	return 0;
}