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Diffstat (limited to 'src/scalar_low_impl.h')
-rw-r--r-- | src/scalar_low_impl.h | 114 |
1 files changed, 114 insertions, 0 deletions
diff --git a/src/scalar_low_impl.h b/src/scalar_low_impl.h new file mode 100644 index 0000000000..4f94441f49 --- /dev/null +++ b/src/scalar_low_impl.h @@ -0,0 +1,114 @@ +/********************************************************************** + * Copyright (c) 2015 Andrew Poelstra * + * Distributed under the MIT software license, see the accompanying * + * file COPYING or http://www.opensource.org/licenses/mit-license.php.* + **********************************************************************/ + +#ifndef _SECP256K1_SCALAR_REPR_IMPL_H_ +#define _SECP256K1_SCALAR_REPR_IMPL_H_ + +#include "scalar.h" + +#include <string.h> + +SECP256K1_INLINE static int secp256k1_scalar_is_even(const secp256k1_scalar *a) { + return !(*a & 1); +} + +SECP256K1_INLINE static void secp256k1_scalar_clear(secp256k1_scalar *r) { *r = 0; } +SECP256K1_INLINE static void secp256k1_scalar_set_int(secp256k1_scalar *r, unsigned int v) { *r = v; } + +SECP256K1_INLINE static unsigned int secp256k1_scalar_get_bits(const secp256k1_scalar *a, unsigned int offset, unsigned int count) { + if (offset < 32) + return ((*a >> offset) & ((((uint32_t)1) << count) - 1)); + else + return 0; +} + +SECP256K1_INLINE static unsigned int secp256k1_scalar_get_bits_var(const secp256k1_scalar *a, unsigned int offset, unsigned int count) { + return secp256k1_scalar_get_bits(a, offset, count); +} + +SECP256K1_INLINE static int secp256k1_scalar_check_overflow(const secp256k1_scalar *a) { return *a >= EXHAUSTIVE_TEST_ORDER; } + +static int secp256k1_scalar_add(secp256k1_scalar *r, const secp256k1_scalar *a, const secp256k1_scalar *b) { + *r = (*a + *b) % EXHAUSTIVE_TEST_ORDER; + return *r < *b; +} + +static void secp256k1_scalar_cadd_bit(secp256k1_scalar *r, unsigned int bit, int flag) { + if (flag && bit < 32) + *r += (1 << bit); +#ifdef VERIFY + VERIFY_CHECK(secp256k1_scalar_check_overflow(r) == 0); +#endif +} + +static void secp256k1_scalar_set_b32(secp256k1_scalar *r, const unsigned char *b32, int *overflow) { + const int base = 0x100 % EXHAUSTIVE_TEST_ORDER; + int i; + *r = 0; + for (i = 0; i < 32; i++) { + *r = ((*r * base) + b32[i]) % EXHAUSTIVE_TEST_ORDER; + } + /* just deny overflow, it basically always happens */ + if (overflow) *overflow = 0; +} + +static void secp256k1_scalar_get_b32(unsigned char *bin, const secp256k1_scalar* a) { + memset(bin, 0, 32); + bin[28] = *a >> 24; bin[29] = *a >> 16; bin[30] = *a >> 8; bin[31] = *a; +} + +SECP256K1_INLINE static int secp256k1_scalar_is_zero(const secp256k1_scalar *a) { + return *a == 0; +} + +static void secp256k1_scalar_negate(secp256k1_scalar *r, const secp256k1_scalar *a) { + if (*a == 0) { + *r = 0; + } else { + *r = EXHAUSTIVE_TEST_ORDER - *a; + } +} + +SECP256K1_INLINE static int secp256k1_scalar_is_one(const secp256k1_scalar *a) { + return *a == 1; +} + +static int secp256k1_scalar_is_high(const secp256k1_scalar *a) { + return *a > EXHAUSTIVE_TEST_ORDER / 2; +} + +static int secp256k1_scalar_cond_negate(secp256k1_scalar *r, int flag) { + if (flag) secp256k1_scalar_negate(r, r); + return flag ? -1 : 1; +} + +static void secp256k1_scalar_mul(secp256k1_scalar *r, const secp256k1_scalar *a, const secp256k1_scalar *b) { + *r = (*a * *b) % EXHAUSTIVE_TEST_ORDER; +} + +static int secp256k1_scalar_shr_int(secp256k1_scalar *r, int n) { + int ret; + VERIFY_CHECK(n > 0); + VERIFY_CHECK(n < 16); + ret = *r & ((1 << n) - 1); + *r >>= n; + return ret; +} + +static void secp256k1_scalar_sqr(secp256k1_scalar *r, const secp256k1_scalar *a) { + *r = (*a * *a) % EXHAUSTIVE_TEST_ORDER; +} + +static void secp256k1_scalar_split_128(secp256k1_scalar *r1, secp256k1_scalar *r2, const secp256k1_scalar *a) { + *r1 = *a; + *r2 = 0; +} + +SECP256K1_INLINE static int secp256k1_scalar_eq(const secp256k1_scalar *a, const secp256k1_scalar *b) { + return *a == *b; +} + +#endif |