## File: bn_mp_set_double.c

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libtommath 1.1.0-3
 `1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162` ``````#include "tommath_private.h" #ifdef BN_MP_SET_DOUBLE_C /* LibTomMath, multiple-precision integer library -- Tom St Denis * * LibTomMath is a library that provides multiple-precision * integer arithmetic as well as number theoretic functionality. * * The library was designed directly after the MPI library by * Michael Fromberger but has been written from scratch with * additional optimizations in place. * * SPDX-License-Identifier: Unlicense */ #if defined(__STDC_IEC_559__) || defined(__GCC_IEC_559) int mp_set_double(mp_int *a, double b) { uint64_t frac; int exp, res; union { double dbl; uint64_t bits; } cast; cast.dbl = b; exp = (int)((unsigned)(cast.bits >> 52) & 0x7FFU); frac = (cast.bits & ((1ULL << 52) - 1ULL)) | (1ULL << 52); if (exp == 0x7FF) { /* +-inf, NaN */ return MP_VAL; } exp -= 1023 + 52; res = mp_set_long_long(a, frac); if (res != MP_OKAY) { return res; } res = (exp < 0) ? mp_div_2d(a, -exp, a, NULL) : mp_mul_2d(a, exp, a); if (res != MP_OKAY) { return res; } if (((cast.bits >> 63) != 0ULL) && (mp_iszero(a) == MP_NO)) { SIGN(a) = MP_NEG; } return MP_OKAY; } #else /* pragma message() not supported by several compilers (in mostly older but still used versions) */ # ifdef _MSC_VER # pragma message("mp_set_double implementation is only available on platforms with IEEE754 floating point format") # else # warning "mp_set_double implementation is only available on platforms with IEEE754 floating point format" # endif #endif #endif /* ref: HEAD -> master, tag: v1.1.0 */ /* git commit: 08549ad6bc8b0cede0b357a9c341c5c6473a9c55 */ /* commit time: 2019-01-28 20:32:32 +0100 */ ``````