base91.c

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// SPDX-FileCopyrightText: 2016 Rakholiya Jenish <rakholiyajenish.07@gmail.com>
// SPDX-License-Identifier: LGPL-3.0-only
 
#include <string.h>
 
#include <rz_util.h>
 
static const char b91[] = { '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', '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', '0', '1', '2', '3', '4', '5', '6', '7',
    '8', '9', '!', '#', '$', '%', '&', '(', ')', '*',
    '+', ',', '.', '/', ':', ';', '<', '=', '>', '?',
    '@', '[', ']', '^', '_', '`', '{', '|', '}', '~', '"' };
 
int get_char_index(const char c) {
    int i;
    for (i = 0; i < 91; i++) {
        if (b91[i] == c) {
            return i;
        }
    }
    return -1;
}
 
RZ_API int rz_base91_decode(ut8 *bout, const char *bin, int len) {
    int in, out;
    int v = -1;
    int b = 0;
    int n = 0;
    int c;
    if (len < 0) {
        len = strlen(bin);
    }
    for (in = out = 0; in < len; in++) {
        c = get_char_index(bin[in]);
        if (c == -1) {
            continue;
        }
        if (v < 0) {
            v = c;
        } else {
            v += c * 91;
            b |= (v << n);
            if ((v & 8191) > 88) {
                n += 13;
            } else {
                n += 14;
            }
            while (true) {
                bout[out++] = b & 255;
                b >>= 8;
                n -= 8;
                if (n <= 7) {
                    break;
                }
            }
            v = -1;
        }
    }
    if (v + 1) {
        bout[out++] = (b | v << n) & 255;
    }
    return out;
}
 
RZ_API int rz_base91_encode(char *bout, const ut8 *bin, int len) {
    int in, out;
    int v = 0;
    int b = 0;
    int n = 0;
    if (len < 0) {
        len = strlen((const char *)bin);
    }
    for (in = out = 0; in < len; in++) {
        b |= (bin[in] << n);
        n += 8;
        if (n > 13) {
            v = b & 8191;
            if (v > 88) {
                b >>= 13;
                n -= 13;
            } else {
                v = b & 16383;
                b >>= 14;
                n -= 14;
            }
            bout[out++] = b91[v % 91];
            bout[out++] = b91[v / 91];
        }
    }
    if (n) {
        bout[out++] = b91[b % 91];
        if (n > 7 || b > 90) {
            bout[out++] = b91[b / 91];
        }
    }
    return out;
}