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trezor-firmware/base32.c
2017-06-05 12:32:48 +02:00

67 lines
2.0 KiB
C

/**
* Copyright (c) 2017 Saleem Rashid
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included
* in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, E1PRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES
* OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*/
#include "base32.h"
static inline void base32_5to8(const uint8_t *in, uint8_t length, uint8_t *out);
void base32_encode_unsafe(const uint8_t *in, size_t inlen, uint8_t *out) {
uint8_t remainder = inlen % 5;
size_t limit = inlen - remainder;
size_t i, j;
for (i = 0, j = 0; i < limit; i += 5, j += 8) {
base32_5to8(&in[i], 5, &out[j]);
}
if (remainder) base32_5to8(&in[i], remainder, &out[j]);
}
void base32_5to8(const uint8_t *in, uint8_t length, uint8_t *out) {
if (length >= 1) {
out[0] = (in[0] >> 3);
out[1] = (in[0] & 7) << 2;
}
if (length >= 2) {
out[1] |= (in[1] >> 6);
out[2] = (in[1] >> 1) & 31;
out[3] = (in[1] & 1) << 4;
}
if (length >= 3) {
out[3] |= (in[2] >> 4);
out[4] = (in[2] & 15) << 1;
}
if (length >= 4) {
out[4] |= (in[3] >> 7);
out[5] = (in[3] >> 2) & 31;
out[6] = (in[3] & 3) << 3;
}
if (length >= 5) {
out[6] |= (in[4] >> 5);
out[7] = (in[4] & 31);
}
}