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/***********************************************************************
* Copyright (c) 2013, 2014 Pieter Wuille *
* Distributed under the MIT software license, see the accompanying *
* file COPYING or https://www.opensource.org/licenses/mit-license.php.*
***********************************************************************/
#ifndef SECP256K1_FIELD_REPR_H
#define SECP256K1_FIELD_REPR_H
#include <stdint.h>
/** This field implementation represents the value as 5 uint64_t limbs in base
* 2^52. */
typedef struct {
/* A field element f represents the sum(i=0..4, f.n[i] << (i*52)) mod p,
* where p is the field modulus, 2^256 - 2^32 - 977.
*
* The individual limbs f.n[i] can exceed 2^52; the field's magnitude roughly
* corresponds to how much excess is allowed. The value
* sum(i=0..4, f.n[i] << (i*52)) may exceed p, unless the field element is
* normalized. */
uint64_t n[5];
/*
* Magnitude m requires:
* n[i] <= 2 * m * (2^52 - 1) for i=0..3
* n[4] <= 2 * m * (2^48 - 1)
*
* Normalized requires:
* n[i] <= (2^52 - 1) for i=0..3
* sum(i=0..4, n[i] << (i*52)) < p
* (together these imply n[4] <= 2^48 - 1)
*/
SECP256K1_FE_VERIFY_FIELDS
} 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) \
}
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 */
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