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authorDavid Robillard <d@drobilla.net>2019-09-29 22:37:30 +0200
committerDavid Robillard <d@drobilla.net>2020-10-27 13:13:58 +0100
commit30d845380249d1de3a28e12407c5263629424c6d (patch)
tree4af7d31598e60462367f3692960550a1271c0979
parent992c8bce3e1938609193561028d67b86753e6e5b (diff)
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Add IEEE floating point utility header
-rw-r--r--src/ieee_float.h55
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