[LIBM] Import win-libm from AMD

Source: https://github.com/amd/win-libm

sdk/lib/crt/math/libm_sse2/_copysignf.c

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+
+/*******************************************************************************
+MIT License
+-----------
+
+Copyright (c) 2002-2019 Advanced Micro Devices, Inc.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this Software and associated documentaon files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
+*******************************************************************************/
+
+#include "libm.h"
+#include "libm_util.h"
+
+  /* Returns the absolute value of x with the sign of y.
+     NaNs are not considered special; their sign bits are handled
+     the same as for any other number. */
+
+float FN_PROTOTYPE(_copysignf)(float x, float y)
+{
+  unsigned int ux, uy;
+  GET_BITS_SP32(x, ux);
+  GET_BITS_SP32(y, uy);
+  if ((ux ^ uy) & SIGNBIT_SP32)
+     PUT_BITS_SP32(ux ^ SIGNBIT_SP32, x);
+  return x;
+}