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author | David Robillard <d@drobilla.net> | 2019-09-29 22:37:30 +0200 |
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committer | David Robillard <d@drobilla.net> | 2020-10-27 13:13:58 +0100 |
commit | 30d845380249d1de3a28e12407c5263629424c6d (patch) | |
tree | 4af7d31598e60462367f3692960550a1271c0979 | |
parent | 992c8bce3e1938609193561028d67b86753e6e5b (diff) | |
download | serd-30d845380249d1de3a28e12407c5263629424c6d.tar.gz serd-30d845380249d1de3a28e12407c5263629424c6d.tar.bz2 serd-30d845380249d1de3a28e12407c5263629424c6d.zip |
Add IEEE floating point utility header
-rw-r--r-- | src/ieee_float.h | 55 |
1 files changed, 55 insertions, 0 deletions
diff --git a/src/ieee_float.h b/src/ieee_float.h new file mode 100644 index 00000000..adf2b6cf --- /dev/null +++ b/src/ieee_float.h @@ -0,0 +1,55 @@ +/* + Copyright 2019-2020 David Robillard <http://drobilla.net> + + Permission to use, copy, modify, and/or distribute this software for any + purpose with or without fee is hereby granted, provided that the above + copyright notice and this permission notice appear in all copies. + + THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES + WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF + MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR + ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES + WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN + ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF + OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. +*/ + +#ifndef SERD_IEEE_FLOAT_H +#define SERD_IEEE_FLOAT_H + +#include <float.h> +#include <math.h> +#include <stdbool.h> +#include <stdint.h> +#include <string.h> + +static const int dbl_physical_mant_dig = DBL_MANT_DIG - 1; +static const uint64_t dbl_mant_mask = 0x000FFFFFFFFFFFFFull; +static const uint64_t dbl_expt_mask = 0x7FF0000000000000ul; +static const uint64_t dbl_hidden_bit = 0x0010000000000000ul; +static const int dbl_expt_bias = 0x3FF + DBL_MANT_DIG - 1; +static const int dbl_subnormal_expt = -0x3FF - DBL_MANT_DIG + 2; + +/// Return the raw representation of a double +static inline uint64_t +double_to_rep(const double d) +{ + uint64_t rep; + memcpy(&rep, &d, sizeof(rep)); + return rep; +} + +/// Return true if the lower boundary is closer than the upper boundary +static inline bool +double_lower_boundary_is_closer(const double d) +{ + const uint64_t rep = double_to_rep(d); + const uint64_t mant = rep & dbl_mant_mask; + const uint64_t expt = rep & dbl_expt_mask; + const bool is_subnormal = expt == 0; + + // True when f = 2^(p-1) (except for the smallest normal) + return !is_subnormal && mant == 0; +} + +#endif // SERD_IEEE_FLOAT_H |