42 lines
1.0 KiB
C
42 lines
1.0 KiB
C
#include "amplify_tommath_private.h"
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#ifdef AMPLIFY_BN_MP_SET_DOUBLE_C
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/* LibTomMath, multiple-precision integer library -- Tom St Denis */
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/* SPDX-License-Identifier: Unlicense */
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/* Modifications Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved. */
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#if defined(__STDC_IEC_559__) || defined(__GCC_IEC_559)
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amplify_mp_err amplify_mp_set_double(amplify_mp_int *a, double b)
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{
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uint64_t frac;
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int exp;
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amplify_mp_err err;
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union {
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double dbl;
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uint64_t bits;
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} cast;
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cast.dbl = b;
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exp = (int)((unsigned)(cast.bits >> 52) & 0x7FFu);
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frac = (cast.bits & ((1uLL << 52) - 1uLL)) | (1uLL << 52);
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if (exp == 0x7FF) { /* +-inf, NaN */
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return AMPLIFY_MP_VAL;
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}
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exp -= 1023 + 52;
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amplify_mp_set_u64(a, frac);
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err = (exp < 0) ? amplify_mp_div_2d(a, -exp, a, NULL) : amplify_mp_mul_2d(a, exp, a);
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if (err != AMPLIFY_MP_OKAY) {
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return err;
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}
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if (((cast.bits >> 63) != 0uLL) && !AMPLIFY_MP_IS_ZERO(a)) {
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a->sign = AMPLIFY_MP_NEG;
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}
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return AMPLIFY_MP_OKAY;
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}
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#endif
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#endif
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