From 27146f7e0c67367abe2d1b4d879cdf2f6285f367 Mon Sep 17 00:00:00 2001
From: Eugen Wissner <belka@caraus.de>
Date: Sat, 16 Sep 2017 22:35:31 +0200
Subject: [PATCH] Add tanya.math.fp

---
 source/tanya/math/fp.d | 213 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 213 insertions(+)
 create mode 100644 source/tanya/math/fp.d

diff --git a/source/tanya/math/fp.d b/source/tanya/math/fp.d
new file mode 100644
index 0000000..7178213
--- /dev/null
+++ b/source/tanya/math/fp.d
@@ -0,0 +1,213 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * Copyright: Eugene Wissner 2017.
+ * License: $(LINK2 https://www.mozilla.org/en-US/MPL/2.0/,
+ *                  Mozilla Public License, v. 2.0).
+ * Authors: $(LINK2 mailto:info@caraus.de, Eugene Wissner)
+ * Source: $(LINK2 https://github.com/caraus-ecms/tanya/blob/master/source/tanya/math/fp.d,
+ *                 tanya/math/fp.d)
+ */
+module tanya.math.fp;
+
+private union FloatBits(F)
+{
+    F floating;
+    static if (ieeePrecision!F == IEEEPrecision.single)
+    {
+        uint integral;
+    }
+    else static if (ieeePrecision!F == IEEEPrecision.double_)
+    {
+        ulong integral;
+    }
+    else static if (ieeePrecision!F == IEEEPrecision.extended)
+    {
+        struct
+        {
+            ulong mantissa;
+            ushort exp;
+        }
+    }
+    else
+    {
+        static assert(false, "Unsupported IEEE-754 floating point representation");
+    }
+}
+
+enum FloatingPointClass : ubyte
+{
+    nan,
+    zero,
+    infinite,
+    subnormal,
+    normal,
+}
+
+FloatingPointClass classify(F)(F x)
+if (isFloatingPoint!F)
+{
+    if (x == 0)
+    {
+        return FloatingPointClass.zero;
+    }
+    FloatBits!F bits;
+    bits.floating = abs(x);
+
+    static if (ieeePrecision!F == IEEEPrecision.single)
+    {
+        if (bits.integral > 0x7f800000)
+        {
+            return FloatingPointClass.nan;
+        }
+        else if (bits.integral == 0x7f800000)
+        {
+            return FloatingPointClass.infinite;
+        }
+        else if (bits.integral < 0x800000)
+        {
+            return FloatingPointClass.subnormal;
+        }
+    }
+    else static if (ieeePrecision!F == IEEEPrecision.double_)
+    {
+        if (bits.integral > 0x7ff0000000000000)
+        {
+            return FloatingPointClass.nan;
+        }
+        else if (bits.integral == 0x7ff0000000000000)
+        {
+            return FloatingPointClass.infinite;
+        }
+        else if (bits.integral < 0x10000000000000)
+        {
+            return FloatingPointClass.subnormal;
+        }
+    }
+    else static if (ieeePrecision!F == IEEEPrecision.extended)
+    {
+    }
+
+    return FloatingPointClass.normal;
+}
+
+bool isFinite(F)(F x)
+if (isFloatingPoint!F)
+{
+    static if (ieeePrecision!F == IEEEPrecision.single)
+    {
+        FloatBits!F bits;
+        bits.floating = x;
+        bits.integral &= 0x7f800000;
+        return bits.integral != 0x7f800000;
+    }
+    else static if (ieeePrecision!F == IEEEPrecision.double_)
+    {
+        FloatBits!F bits;
+        bits.floating = x;
+        bits.integral &= 0x7ff0000000000000;
+        return bits.integral != 0x7ff0000000000000;
+    }
+    else static if (ieeePrecision!F == IEEEPrecision.extended)
+    {
+        FloatBits!F bits;
+        bits.floating = abs(x);
+        return exponent != 0x7fff;
+    }
+}
+
+bool isNaN(F)(F x)
+if (isFloatingPoint!F)
+{
+    static if (ieeePrecision!F == IEEEPrecision.single)
+    {
+        FloatBits!F bits;
+        bits.floating = abs(x);
+        return bits.integral > 0x7f800000;
+    }
+    else static if (ieeePrecision!F == IEEEPrecision.double_)
+    {
+        FloatBits!F bits;
+        bits.floating = abs(x);
+        return bits.integral > 0x7ff0000000000000;
+    }
+    else static if (ieeePrecision!F == IEEEPrecision.extended)
+    {
+        FloatBits!F bits;
+        bits.floating = abs(x);
+        return bits.exponent == 0x7fff && bits.mantissa != 0;
+    }
+}
+
+bool isInfinity(F)(F x)
+if (isFloatingPoint!F)
+{
+    static if (ieeePrecision!F == IEEEPrecision.single)
+    {
+        FloatBits!F bits;
+        bits.floating = abs(x);
+        return bits.integral == 0x7f800000;
+    }
+    else static if (ieeePrecision!F == IEEEPrecision.double_)
+    {
+        FloatBits!F bits;
+        bits.floating = abs(x);
+        return bits.integral == 0x7ff0000000000000;
+    }
+    else static if (ieeePrecision!F == IEEEPrecision.extended)
+    {
+        FloatBits!F bits;
+        bits.floating = abs(x);
+        return bits.exponent == 0x7fff && bits.mantissa == 0;
+    }
+}
+
+bool isSubnormal(F)(F x)
+if (isFloatingPoint!F)
+{
+    static if (ieeePrecision!F == IEEEPrecision.single)
+    {
+        FloatBits!F bits;
+        bits.floating = abs(x);
+        return bits.integral < 0x800000;
+    }
+    else static if (ieeePrecision!F == IEEEPrecision.double_)
+    {
+        FloatBits!F bits;
+        bits.floating = abs(x);
+        return bits.integral < 0x10000000000000;
+    }
+    else static if (ieeePrecision!F == IEEEPrecision.extended)
+    {
+        FloatBits!F bits;
+        bits.floating = abs(x);
+        return bits.exponent == 0 && bits.mantissa != 0;
+    }
+}
+
+bool isNormal(F)(F x)
+if (isFloatingPoint!F)
+{
+    static if (ieeePrecision!F == IEEEPrecision.single)
+    {
+        FloatBits!F bits;
+        bits.floating = x;
+        bits.integral &= 0x7f800000;
+        return bits.integral != 0 && bits.integral != 0x7f800000;
+    }
+    else static if (ieeePrecision!F == IEEEPrecision.double_)
+    {
+        FloatBits!F bits;
+        bits.floating = x;
+        bits.integral &= 0x7ff0000000000000;
+        return bits.integral != 0 && bits.integral != 0x7ff0000000000000;
+    }
+    else static if (ieeePrecision!F == IEEEPrecision.extended)
+    {
+        FloatBits!F bits;
+        bits.floating = abs(x);
+        return bits.exponent != 0 && exponent != 0x7fff;
+    }
+}