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diff --git a/libopus/celt/float_cast.h b/libopus/celt/float_cast.h
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+/* Copyright (C) 2001 Erik de Castro Lopo <erikd AT mega-nerd DOT com> */
+/*
+   Redistribution and use in source and binary forms, with or without
+   modification, are permitted provided that the following conditions
+   are met:
+
+   - Redistributions of source code must retain the above copyright
+   notice, this list of conditions and the following disclaimer.
+
+   - Redistributions in binary form must reproduce the above copyright
+   notice, this list of conditions and the following disclaimer in the
+   documentation and/or other materials provided with the distribution.
+
+   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+   ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
+   OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+   EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+   PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+   PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+   LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+   NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+   SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+/* Version 1.1 */
+
+#ifndef FLOAT_CAST_H
+#define FLOAT_CAST_H
+
+
+#include "arch.h"
+
+/*============================================================================
+**      On Intel Pentium processors (especially PIII and probably P4), converting
+**      from float to int is very slow. To meet the C specs, the code produced by
+**      most C compilers targeting Pentium needs to change the FPU rounding mode
+**      before the float to int conversion is performed.
+**
+**      Changing the FPU rounding mode causes the FPU pipeline to be flushed. It
+**      is this flushing of the pipeline which is so slow.
+**
+**      Fortunately the ISO C99 specifications define the functions lrint, lrintf,
+**      llrint and llrintf which fix this problem as a side effect.
+**
+**      On Unix-like systems, the configure process should have detected the
+**      presence of these functions. If they weren't found we have to replace them
+**      here with a standard C cast.
+*/
+
+/*
+**      The C99 prototypes for lrint and lrintf are as follows:
+**
+**              long int lrintf (float x) ;
+**              long int lrint  (double x) ;
+*/
+
+/*      The presence of the required functions are detected during the configure
+**      process and the values HAVE_LRINT and HAVE_LRINTF are set accordingly in
+**      the config.h file.
+*/
+
+/* With GCC, when SSE is available, the fastest conversion is cvtss2si. */
+#if defined(__GNUC__) && defined(__SSE__)
+
+#include <xmmintrin.h>
+static OPUS_INLINE opus_int32 float2int(float x) {return _mm_cvt_ss2si(_mm_set_ss(x));}
+
+#elif defined(HAVE_LRINTF)
+
+/*      These defines enable functionality introduced with the 1999 ISO C
+**      standard. They must be defined before the inclusion of math.h to
+**      engage them. If optimisation is enabled, these functions will be
+**      inlined. With optimisation switched off, you have to link in the
+**      maths library using -lm.
+*/
+
+#define _ISOC9X_SOURCE 1
+#define _ISOC99_SOURCE 1
+
+#define __USE_ISOC9X 1
+#define __USE_ISOC99 1
+
+#include <math.h>
+#define float2int(x) lrintf(x)
+
+#elif (defined(HAVE_LRINT))
+
+#define _ISOC9X_SOURCE 1
+#define _ISOC99_SOURCE 1
+
+#define __USE_ISOC9X 1
+#define __USE_ISOC99 1
+
+#include <math.h>
+#define float2int(x) lrint(x)
+
+#elif (defined(_MSC_VER) && _MSC_VER >= 1400) && (defined(_M_X64) || (defined(_M_IX86_FP) && _M_IX86_FP >= 1))
+        #include <xmmintrin.h>
+
+        static __inline long int float2int(float value)
+        {
+                return _mm_cvtss_si32(_mm_load_ss(&value));
+        }
+#elif (defined(_MSC_VER) && _MSC_VER >= 1400) && defined (_M_IX86)
+        #include <math.h>
+
+        /*      Win32 doesn't seem to have these functions.
+        **      Therefore implement OPUS_INLINE versions of these functions here.
+        */
+
+        static __inline long int
+        float2int (float flt)
+        {       int intgr;
+
+                _asm
+                {       fld flt
+                        fistp intgr
+                } ;
+
+                return intgr ;
+        }
+
+#else
+
+#if (defined(__GNUC__) && defined(__STDC__) && __STDC__ && __STDC_VERSION__ >= 199901L)
+        /* supported by gcc in C99 mode, but not by all other compilers */
+        //#warning "Don't have the functions lrint() and lrintf ()."
+        //#warning "Replacing these functions with a standard C cast."
+#endif /* __STDC_VERSION__ >= 199901L */
+        #include <math.h>
+        #define float2int(flt) ((int)(floor(.5+flt)))
+#endif
+
+#ifndef DISABLE_FLOAT_API
+static OPUS_INLINE opus_int16 FLOAT2INT16(float x)
+{
+   x = x*CELT_SIG_SCALE;
+   x = MAX32(x, -32768);
+   x = MIN32(x, 32767);
+   return (opus_int16)float2int(x);
+}
+#endif /* DISABLE_FLOAT_API */
+
+#endif /* FLOAT_CAST_H */