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usr / src / contrib / bearssl / src / int /

📁 ..
📄 i15_add.c(1.45 KB)
📄 i15_bitlen.c(1.42 KB)
📄 i15_decmod.c(3.45 KB)
📄 i15_decode.c(1.59 KB)
📄 i15_decred.c(2.52 KB)
📄 i15_encode.c(1.6 KB)
📄 i15_fmont.c(1.86 KB)
📄 i15_iszero.c(1.32 KB)
📄 i15_moddiv.c(12.25 KB)
📄 i15_modpow.c(1.68 KB)
📄 i15_modpow2.c(4.06 KB)
📄 i15_montmul.c(7.28 KB)
📄 i15_mulacc.c(1.85 KB)
📄 i15_muladd.c(4.57 KB)
📄 i15_ninv15.c(1.35 KB)
📄 i15_reduce.c(1.98 KB)
📄 i15_rshift.c(1.44 KB)
📄 i15_sub.c(1.45 KB)
📄 i15_tmont.c(1.3 KB)
📄 i31_add.c(1.47 KB)
📄 i31_bitlen.c(1.42 KB)
📄 i31_decmod.c(3.46 KB)
📄 i31_decode.c(1.63 KB)
📄 i31_decred.c(2.57 KB)
📄 i31_encode.c(1.99 KB)
📄 i31_fmont.c(1.88 KB)
📄 i31_iszero.c(1.32 KB)
📄 i31_moddiv.c(12.91 KB)
📄 i31_modpow.c(2.11 KB)
📄 i31_modpow2.c(4.06 KB)
📄 i31_montmul.c(3.75 KB)
📄 i31_mulacc.c(2.24 KB)
📄 i31_muladd.c(4.51 KB)
📄 i31_ninv31.c(1.33 KB)
📄 i31_reduce.c(1.98 KB)
📄 i31_rshift.c(1.45 KB)
📄 i31_sub.c(1.46 KB)
📄 i31_tmont.c(1.3 KB)
📄 i32_add.c(1.57 KB)
📄 i32_bitlen.c(1.42 KB)
📄 i32_decmod.c(2.2 KB)
📄 i32_decode.c(1.68 KB)
📄 i32_decred.c(2.67 KB)
📄 i32_div32.c(1.66 KB)
📄 i32_encode.c(1.88 KB)
📄 i32_fmont.c(1.86 KB)
📄 i32_iszero.c(1.32 KB)
📄 i32_modpow.c(2.11 KB)
📄 i32_montmul.c(1.98 KB)
📄 i32_mulacc.c(1.65 KB)
📄 i32_muladd.c(4.06 KB)
📄 i32_ninv32.c(1.31 KB)
📄 i32_reduce.c(1.98 KB)
📄 i32_sub.c(1.57 KB)
📄 i32_tmont.c(1.3 KB)
📄 i62_modpow2.c(12.71 KB)

Editing: i32_decred.c

/*
 * Copyright (c) 2016 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_i32_decode_reduce(uint32_t *x,
	const void *src, size_t len, const uint32_t *m)
{
	uint32_t m_bitlen;
	size_t mblen, k, q;
	const unsigned char *buf;

m_bitlen = m[0];

/*
	 * Special case for an invalid modulus.
	 */
	if (m_bitlen == 0) {
		x[0] = 0;
		return;
	}

/*
	 * Clear the destination.
	 */
	br_i32_zero(x, m_bitlen);

/*
	 * First decode directly as many bytes as possible without
	 * reduction, taking care to leave a number of bytes which
	 * is a multiple of 4.
	 */
	mblen = (m_bitlen + 7) >> 3;
	k = mblen - 1;

/*
	 * Up to k bytes can be safely decoded.
	 */
	if (k >= len) {
		br_i32_decode(x, src, len);
		x[0] = m_bitlen;
		return;
	}

/*
	 * We want to first inject some bytes with direct decoding,
	 * then extra bytes by whole 32-bit words. First compute
	 * the size that should be injected that way.
	 */
	buf = src;
	q = (len - k + 3) & ~(size_t)3;

/*
	 * It may happen that this is more than what we already have
	 * (by at most 3 bytes). Such a case may happen only with
	 * a very short modulus. In that case, we must process the first
	 * bytes "manually".
	 */
	if (q > len) {
		int i;
		uint32_t w;

w = 0;
		for (i = 0; i < 4; i ++) {
			w <<= 8;
			if (q <= len) {
				w |= buf[len - q];
			}
			q --;
		}
		br_i32_muladd_small(x, w, m);
	} else {
		br_i32_decode(x, buf, len - q);
		x[0] = m_bitlen;
	}

/*
	 * At that point, we have exactly q bytes to inject, and q is
	 * a multiple of 4.
	 */
	for (k = len - q; k < len; k += 4) {
		br_i32_muladd_small(x, br_dec32be(buf + k), m);
	}
}

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Editing: i32_decred.c

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