ref: 9540077419c8b87d69abc26d84eb4631b8bd427d
dir: /libcelt/float_cast.h/
/* ** Copyright (C) 2001 Erik de Castro Lopo <erikd AT mega-nerd DOT com> ** ** Permission to use, copy, modify, distribute, and sell this file for any ** purpose is hereby granted without fee, provided that the above copyright ** and this permission notice appear in all copies. No representations are ** made about the suitability of this software for any purpose. It is ** provided "as is" without express or implied warranty. */ /* Version 1.1 */ #ifndef FLOAT_CAST_H #define FLOAT_CAST_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. */ #if (HAVE_LRINTF) /*#if 0*/ /* 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 (WIN32) || defined (_WIN32)) #include <math.h> /* Win32 doesn't seem to have these functions. ** Therefore implement inline versions of these functions here. */ __inline long int float2int (float flt) { int intgr; _asm { fld flt fistp intgr } ; return intgr ; } #else #ifdef __GNUC__ /* supported by gcc, 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 /* __GNUC__ */ #include <math.h> #define float2int(flt) ((int)(floor(.5+flt))) #endif #endif /* FLOAT_CAST_H */