bearssl-rs/bearssl-sys/bundled/src/i15_encode.c

57 lines
1.6 KiB
C

/*
* Copyright (c) 2017 Thomas Pornin <pornin@bolet.org>
*
* 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,
* EXPRESS 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 "inner.h"
/* see inner.h */
void
br_i15_encode(void *dst, size_t len, const uint16_t *x)
{
unsigned char *buf;
size_t u, xlen;
uint32_t acc;
int acc_len;
xlen = (x[0] + 15) >> 4;
if (xlen == 0) {
memset(dst, 0, len);
return;
}
u = 1;
acc = 0;
acc_len = 0;
buf = dst;
while (len -- > 0) {
if (acc_len < 8) {
if (u <= xlen) {
acc += (uint32_t)x[u ++] << acc_len;
}
acc_len += 15;
}
buf[len] = (unsigned char)acc;
acc >>= 8;
acc_len -= 8;
}
}