field_10x26.h (2366B)
1 /*********************************************************************** 2 * Copyright (c) 2013, 2014 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_FIELD_REPR_H 8 #define SECP256K1_FIELD_REPR_H 9 10 #include <stdint.h> 11 12 /** This field implementation represents the value as 10 uint32_t limbs in base 13 * 2^26. */ 14 typedef struct { 15 /* A field element f represents the sum(i=0..9, f.n[i] << (i*26)) mod p, 16 * where p is the field modulus, 2^256 - 2^32 - 977. 17 * 18 * The individual limbs f.n[i] can exceed 2^26; the field's magnitude roughly 19 * corresponds to how much excess is allowed. The value 20 * sum(i=0..9, f.n[i] << (i*26)) may exceed p, unless the field element is 21 * normalized. */ 22 uint32_t n[10]; 23 /* 24 * Magnitude m requires: 25 * n[i] <= 2 * m * (2^26 - 1) for i=0..8 26 * n[9] <= 2 * m * (2^22 - 1) 27 * 28 * Normalized requires: 29 * n[i] <= (2^26 - 1) for i=0..8 30 * sum(i=0..9, n[i] << (i*26)) < p 31 * (together these imply n[9] <= 2^22 - 1) 32 */ 33 SECP256K1_FE_VERIFY_FIELDS 34 } haskellsecp256k1_v0_1_0_fe; 35 36 /* Unpacks a constant into a overlapping multi-limbed FE element. */ 37 #define SECP256K1_FE_CONST_INNER(d7, d6, d5, d4, d3, d2, d1, d0) { \ 38 (d0) & 0x3FFFFFFUL, \ 39 (((uint32_t)d0) >> 26) | (((uint32_t)(d1) & 0xFFFFFUL) << 6), \ 40 (((uint32_t)d1) >> 20) | (((uint32_t)(d2) & 0x3FFFUL) << 12), \ 41 (((uint32_t)d2) >> 14) | (((uint32_t)(d3) & 0xFFUL) << 18), \ 42 (((uint32_t)d3) >> 8) | (((uint32_t)(d4) & 0x3UL) << 24), \ 43 (((uint32_t)d4) >> 2) & 0x3FFFFFFUL, \ 44 (((uint32_t)d4) >> 28) | (((uint32_t)(d5) & 0x3FFFFFUL) << 4), \ 45 (((uint32_t)d5) >> 22) | (((uint32_t)(d6) & 0xFFFFUL) << 10), \ 46 (((uint32_t)d6) >> 16) | (((uint32_t)(d7) & 0x3FFUL) << 16), \ 47 (((uint32_t)d7) >> 10) \ 48 } 49 50 typedef struct { 51 uint32_t n[8]; 52 } haskellsecp256k1_v0_1_0_fe_storage; 53 54 #define SECP256K1_FE_STORAGE_CONST(d7, d6, d5, d4, d3, d2, d1, d0) {{ (d0), (d1), (d2), (d3), (d4), (d5), (d6), (d7) }} 55 #define SECP256K1_FE_STORAGE_CONST_GET(d) d.n[7], d.n[6], d.n[5], d.n[4],d.n[3], d.n[2], d.n[1], d.n[0] 56 57 #endif /* SECP256K1_FIELD_REPR_H */