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/**********************************************************************
* 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
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