Merge #699: Initialize field elements when resulting in infinity

[secp256k1.git] / src / field_5x52.h

/**********************************************************************
 * Copyright (c) 2013, 2014 Pieter Wuille                             *
 * Distributed under the MIT software license, see the accompanying   *
 * file COPYING or http://www.opensource.org/licenses/mit-license.php.*
 **********************************************************************/

#ifndef SECP256K1_FIELD_REPR_H
#define SECP256K1_FIELD_REPR_H

#include <stdint.h>

typedef struct {
    /* X = sum(i=0..4, n[i]*2^(i*52)) mod p
     * where p = 2^256 - 0x1000003D1
     */
    uint64_t n[5];
#ifdef VERIFY
    int magnitude;
    int normalized;
#endif
} secp256k1_fe;

/* Unpacks a constant into a overlapping multi-limbed FE element. */
#define SECP256K1_FE_CONST_INNER(d7, d6, d5, d4, d3, d2, d1, d0) { \
    (d0) | (((uint64_t)(d1) & 0xFFFFFUL) << 32), \
    ((uint64_t)(d1) >> 20) | (((uint64_t)(d2)) << 12) | (((uint64_t)(d3) & 0xFFUL) << 44), \
    ((uint64_t)(d3) >> 8) | (((uint64_t)(d4) & 0xFFFFFFFUL) << 24), \
    ((uint64_t)(d4) >> 28) | (((uint64_t)(d5)) << 4) | (((uint64_t)(d6) & 0xFFFFUL) << 36), \
    ((uint64_t)(d6) >> 16) | (((uint64_t)(d7)) << 16) \
}

#ifdef VERIFY
#define SECP256K1_FE_CONST(d7, d6, d5, d4, d3, d2, d1, d0) {SECP256K1_FE_CONST_INNER((d7), (d6), (d5), (d4), (d3), (d2), (d1), (d0)), 1, 1}
#else
#define SECP256K1_FE_CONST(d7, d6, d5, d4, d3, d2, d1, d0) {SECP256K1_FE_CONST_INNER((d7), (d6), (d5), (d4), (d3), (d2), (d1), (d0))}
#endif

typedef struct {
    uint64_t n[4];
} secp256k1_fe_storage;

#define SECP256K1_FE_STORAGE_CONST(d7, d6, d5, d4, d3, d2, d1, d0) {{ \
    (d0) | (((uint64_t)(d1)) << 32), \
    (d2) | (((uint64_t)(d3)) << 32), \
    (d4) | (((uint64_t)(d5)) << 32), \
    (d6) | (((uint64_t)(d7)) << 32) \
}}

#define SECP256K1_FE_STORAGE_CONST_GET(d) \
    (uint32_t)(d.n[3] >> 32), (uint32_t)d.n[3], \
    (uint32_t)(d.n[2] >> 32), (uint32_t)d.n[2], \
    (uint32_t)(d.n[1] >> 32), (uint32_t)d.n[1], \
    (uint32_t)(d.n[0] >> 32), (uint32_t)d.n[0]

#endif /* SECP256K1_FIELD_REPR_H */