//========= Copyright Valve Corporation, All rights reserved. ============//
//
// Purpose:
//
//=====================================================================================//

#ifndef _MATH_PFNS_H_
#define _MATH_PFNS_H_

#if defined(_X360)
#include <xboxmath.h>
#endif

#if !defined(_X360)

// These globals are initialized by mathlib and redirected based on available
// fpu features
extern float (*pfSqrt)(float x);
extern float (*pfRSqrt)(float x);
extern float (*pfRSqrtFast)(float x);
extern void (*pfFastSinCos)(float x, float *s, float *c);
extern float (*pfFastCos)(float x);

// The following are not declared as macros because they are often used in
// limiting situations, and sometimes the compiler simply refuses to inline them
// for some reason
#define FastSqrt(x) (*pfSqrt)(x)
#define FastRSqrt(x) (*pfRSqrt)(x)
#define FastRSqrtFast(x) (*pfRSqrtFast)(x)
#define FastSinCos(x, s, c) (*pfFastSinCos)(x, s, c)
#define FastCos(x) (*pfFastCos)(x)

#if defined(__i386__) || defined(_M_IX86)
// On x86, the inline FPU or SSE sqrt instruction is faster than
// the overhead of setting up a function call and saving/restoring
// the FPU or SSE register state and can be scheduled better, too.
#undef FastSqrt
#define FastSqrt(x) ::sqrtf(x)
#endif

#endif  // !_X360

#if defined(_X360)

FORCEINLINE float _VMX_Sqrt(float x) { return __fsqrts(x); }

FORCEINLINE float _VMX_RSqrt(float x) {
    float rroot = __frsqrte(x);

    // Single iteration NewtonRaphson on reciprocal square root estimate
    return (0.5f * rroot) * (3.0f - (x * rroot) * rroot);
}

FORCEINLINE float _VMX_RSqrtFast(float x) { return __frsqrte(x); }

FORCEINLINE void _VMX_SinCos(float a, float *pS, float *pC) {
    XMScalarSinCos(pS, pC, a);
}

FORCEINLINE float _VMX_Cos(float a) { return XMScalarCos(a); }

// the 360 has fixed hw and calls directly
#define FastSqrt(x) _VMX_Sqrt(x)
#define FastRSqrt(x) _VMX_RSqrt(x)
#define FastRSqrtFast(x) _VMX_RSqrtFast(x)
#define FastSinCos(x, s, c) _VMX_SinCos(x, s, c)
#define FastCos(x) _VMX_Cos(x)

#endif  // _X360

#endif  // _MATH_PFNS_H_