github.com/ethereum/go-ethereum@v1.16.1/crypto/secp256k1/libsecp256k1/src/scalar_low.h (about)

     1  /***********************************************************************
     2   * Copyright (c) 2015, 2022 Andrew Poelstra, Pieter Wuille             *
     3   * Distributed under the MIT software license, see the accompanying    *
     4   * file COPYING or https://www.opensource.org/licenses/mit-license.php.*
     5   ***********************************************************************/
     6  
     7  #ifndef SECP256K1_SCALAR_REPR_H
     8  #define SECP256K1_SCALAR_REPR_H
     9  
    10  #include <stdint.h>
    11  
    12  /** A scalar modulo the group order of the secp256k1 curve. */
    13  typedef uint32_t secp256k1_scalar;
    14  
    15  /* A compile-time constant equal to 2^32 (modulo order). */
    16  #define SCALAR_2P32 ((0xffffffffUL % EXHAUSTIVE_TEST_ORDER) + 1U)
    17  
    18  /* Compute a*2^32 + b (modulo order). */
    19  #define SCALAR_HORNER(a, b) (((uint64_t)(a) * SCALAR_2P32 + (b)) % EXHAUSTIVE_TEST_ORDER)
    20  
    21  /* Evaluates to the provided 256-bit constant reduced modulo order. */
    22  #define SECP256K1_SCALAR_CONST(d7, d6, d5, d4, d3, d2, d1, d0) SCALAR_HORNER(SCALAR_HORNER(SCALAR_HORNER(SCALAR_HORNER(SCALAR_HORNER(SCALAR_HORNER(SCALAR_HORNER((d7), (d6)), (d5)), (d4)), (d3)), (d2)), (d1)), (d0))
    23  
    24  #endif /* SECP256K1_SCALAR_REPR_H */