Method Codec Aencode.txt

/ *
 * aencode.c
 *
 * Copyright 1995 The Ohio State University.
 *
 * Tom Sanfilippo
 * August 27, 1995
 */

#include <stdlib.h>
#include <string.h>
#include "aencode.h"

static char encoding[65] = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz()";

int bin2ascii(char *data_in, int data_in_len, char **data_out)
{
	int size, current_bit_size,value;
	int i,j,k,l,m = 0;
	int whole_blocks,additional_last_bytes;
	union {
	  struct {
		unsigned int base64_0 : 6;
		unsigned int base64_1 : 6;
		unsigned int base64_2 : 6;
		unsigned int base64_3 : 6;
	  } cvt0;
	  unsigned char base256[3];
	} cvtr;

	whole_blocks = data_in_len / 3;
	additional_last_bytes = data_in_len % 3;
	current_bit_size = data_in_len * 8;
	size = (current_bit_size / 6) + ((current_bit_size % 6) ? 1 : 0);

	if (data_out != NULL)
	{
		*data_out = (char *)malloc(size + 1);
		if (*data_out != NULL)
		{
			for (i = 0; i < whole_blocks + (additional_last_bytes > 0 ? 1 : 0); i++)
			{
				memset(&cvtr, 0, 3);
				j = (i < whole_blocks ? 3 : additional_last_bytes);
				memcpy(&cvtr, data_in + (i * 3), j);
				k = (i < whole_blocks ? 4 : j * 4 / 3 +	(((j * 4) % 3) ? 1 : 0));
				for (l = 0; l < k; l++)
				{
					switch (l)
					{
						case 0:
							value = cvtr.cvt0.base64_0;
							break;
						case 1:
							value = cvtr.cvt0.base64_1;
							break;
						case 2:
							value = cvtr.cvt0.base64_2;
							break;
						case 3:
							value = cvtr.cvt0.base64_3;
					}
					(*data_out)[m] = encoding[value];
					m++;
				}
			}
			(*data_out)[size] = '\0';
			return size + 1;
		}
	}
	return 0;
}
	
int ascii2bin(char *data_in, char **data_out)
{
	int data_in_len, size, current_bit_size, value;
	int i,j,k,l,m = 0;
	int whole_blocks,additional_last_bytes;
	union {
	  struct {
		unsigned int base64_0 : 6;
		unsigned int base64_1 : 6;
		unsigned int base64_2 : 6;
		unsigned int base64_3 : 6;
	  } cvt0;
	  unsigned char base256[3];
	} cvtr;

	data_in_len = strlen(data_in);
	current_bit_size = 6 * data_in_len;
	size = (current_bit_size / 8);
	whole_blocks = size / 3;
	additional_last_bytes = size % 3;

	if (data_out != NULL)
	{
		*data_out = (char *)malloc(size);
		if (*data_out != NULL)
		{
			for (i = 0; i < whole_blocks + (additional_last_bytes > 0 ? 1 : 0); i++)
			{
				memset(&cvtr, 0, 3);
				j = (i < whole_blocks ? 3 : additional_last_bytes);
				k = (i < whole_blocks ? 4 : j * 4 / 3 +	(((j * 4) % 3) ? 1 : 0));
				for (l = 0; l < k; l++)
				{
					if (!(m < data_in_len))
						break;
					value =	strchr(encoding, data_in[m]) - encoding;
					m++;
					switch (l)
					{
						case 0:
							cvtr.cvt0.base64_0 = value;
							break;
						case 1:
							cvtr.cvt0.base64_1 = value;
							break;
						case 2:
							cvtr.cvt0.base64_2 = value;
							break;
						case 3:
							cvtr.cvt0.base64_3 = value;
					}
				}
				memcpy(*data_out + (i * 3), &cvtr, j);
			}
			return size;
		}
	}
	return 0;
}

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