SylFilter

/*

 * LibSylph -- E-Mail client library

 * Copyright (C) 1999-2011 Hiroyuki Yamamoto

 */

#include <ctype.h>

#define UUDECODE(c) (c=='`' ? 0 : c - ' ')

#define N64(i) (i & ~63)

const char uudigit[64] =

{

  '`', '!', '"', '#', '$', '%', '&', '\'',

  '(', ')', '*', '+', ',', '-', '.', '/',

  '0', '1', '2', '3', '4', '5', '6', '7',

  '8', '9', ':', ';', '<', '=', '>', '?',

  '@', 'A', 'B', 'C', 'D', 'E', 'F', 'G',

  'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O',

  'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W',

  'X', 'Y', 'Z', '[', '\\', ']', '^', '_'

};

int touufrombits(unsigned char *out, const unsigned char *in, int inlen)

{

    int len;

    if (inlen > 45) return -1;

    len = (inlen * 4 + 2) / 3 + 1;

    *out++ = uudigit[inlen];

    for (; inlen >= 3; inlen -= 3) {

        *out++ = uudigit[in[0] >> 2];

        *out++ = uudigit[((in[0] << 4) & 0x30) | (in[1] >> 4)];

        *out++ = uudigit[((in[1] << 2) & 0x3c) | (in[2] >> 6)];

        *out++ = uudigit[in[2] & 0x3f];

        in += 3;

    }

    if (inlen > 0) {

        *out++ = uudigit[(in[0] >> 2)];

        if (inlen == 1) {

            *out++ = uudigit[((in[0] << 4) & 0x30)];

        } else {

            *out++ = uudigit[(((in[0] << 4) & 0x30) | (in[1] >> 4))] ;            

            *out++ = uudigit[((in[1] << 2) & 0x3c)];

        }

    }

    *out = '\0';

    return len;

}

int fromuutobits(char *out, const char *in)

{

    int len, outlen, inlen;

    register unsigned char digit1, digit2;

    outlen = UUDECODE(in[0]);

    in += 1;

    if(outlen < 0 || outlen > 45)

        return -2;

    if(outlen == 0)

        return 0;

    inlen = (outlen * 4 + 2) / 3;

    len = 0;

    for( ; inlen>0; inlen-=4) {

        digit1 = UUDECODE(in[0]);

        if (N64(digit1)) return -1;

        digit2 = UUDECODE(in[1]);

        if (N64(digit2)) return -1;

        out[len++] = (digit1 << 2) | (digit2 >> 4);

        if (inlen > 2) {

            digit1 = UUDECODE(in[2]);

            if (N64(digit1)) return -1;

            out[len++] = (digit2 << 4) | (digit1 >> 2);

            if (inlen > 3) {

                digit2 = UUDECODE(in[3]);

                if (N64(digit2)) return -1;

                out[len++] = (digit1 << 6) | digit2;

            }

        }

        in += 4;

    }

    return len == outlen ? len : -3;

}