diff options
Diffstat (limited to 'lib/hcrypto/libtommath/bn_mp_set_double.c')
-rw-r--r-- | lib/hcrypto/libtommath/bn_mp_set_double.c | 47 |
1 files changed, 47 insertions, 0 deletions
diff --git a/lib/hcrypto/libtommath/bn_mp_set_double.c b/lib/hcrypto/libtommath/bn_mp_set_double.c new file mode 100644 index 000000000000..6f91b64f5034 --- /dev/null +++ b/lib/hcrypto/libtommath/bn_mp_set_double.c @@ -0,0 +1,47 @@ +#include "tommath_private.h" +#ifdef BN_MP_SET_DOUBLE_C +/* LibTomMath, multiple-precision integer library -- Tom St Denis */ +/* SPDX-License-Identifier: Unlicense */ + +#if defined(__STDC_IEC_559__) || defined(__GCC_IEC_559) || defined(__x86_64__) || defined(_M_X64) || defined(_M_AMD64) || defined(__i386__) || defined(_M_X86) || defined(__aarch64__) || defined(__arm__) +mp_err mp_set_double(mp_int *a, double b) +{ + uint64_t frac; + int exp; + mp_err err; + 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; + + mp_set_u64(a, frac); + + err = (exp < 0) ? mp_div_2d(a, -exp, a, NULL) : mp_mul_2d(a, exp, a); + if (err != MP_OKAY) { + return err; + } + + if (((cast.bits >> 63) != 0uLL) && !MP_IS_ZERO(a)) { + a->sign = 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 |