/* * Copyright (c) 2014-2016 Dag-Erling Smørgrav * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. The name of the author may not be used to endorse or promote * products derived from this software without specific prior written * permission. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #include "cryb/impl.h" #include <stddef.h> #include <stdint.h> #include <cryb/endian.h> #include <cryb/mpi.h> #include "cryb_mpi_impl.h" /* * Load value from an array of bytes */ int mpi_load(cryb_mpi *X, const uint8_t *a, size_t len) { int i; mpi_zero(X); /* skip zeroes */ while (len > 0 && *a == 0) --len, ++a; if (len == 0) return (0); /* make room */ if (mpi_grow(X, len * 8) != 0) return (-1); /* load whole words */ for (i = 0; len >= 4; ++i, len -= 4) X->words[i] = be32dec(&a[len - 4]); /* load remaining bytes */ switch (len) { case 3: X->words[i] |= a[len - 3] << 16; case 2: X->words[i] |= a[len - 2] << 8; case 1: X->words[i] |= a[len - 1]; break; case 0: --i; CRYB_NO_DEFAULT_CASE; } /* i now points to the msw */ /* compute msb of msw */ /* XXX use flsl() */ for (X->msb = 31; X->msb > 0; --X->msb) if (X->words[i] & (1 << X->msb)) break; /* add msw offset */ X->msb += i * 32 + 1; return (0); }