superbuild/modules/openal-soft/common/alnumeric.h

#ifndef AL_NUMERIC_H
#define AL_NUMERIC_H

#include <stdint.h>
#ifdef HAVE_INTRIN_H
#include <intrin.h>
#endif
#ifdef HAVE_SSE_INTRINSICS
#include <xmmintrin.h>
#endif

#include "opthelpers.h"


inline constexpr int64_t operator "" _i64(unsigned long long int n) noexcept { return static_cast<int64_t>(n); }
inline constexpr uint64_t operator "" _u64(unsigned long long int n) noexcept { return static_cast<uint64_t>(n); }


constexpr inline float minf(float a, float b) noexcept
{ return ((a > b) ? b : a); }
constexpr inline float maxf(float a, float b) noexcept
{ return ((a > b) ? a : b); }
constexpr inline float clampf(float val, float min, float max) noexcept
{ return minf(max, maxf(min, val)); }

constexpr inline double mind(double a, double b) noexcept
{ return ((a > b) ? b : a); }
constexpr inline double maxd(double a, double b) noexcept
{ return ((a > b) ? a : b); }
constexpr inline double clampd(double val, double min, double max) noexcept
{ return mind(max, maxd(min, val)); }

constexpr inline unsigned int minu(unsigned int a, unsigned int b) noexcept
{ return ((a > b) ? b : a); }
constexpr inline unsigned int maxu(unsigned int a, unsigned int b) noexcept
{ return ((a > b) ? a : b); }
constexpr inline unsigned int clampu(unsigned int val, unsigned int min, unsigned int max) noexcept
{ return minu(max, maxu(min, val)); }

constexpr inline int mini(int a, int b) noexcept
{ return ((a > b) ? b : a); }
constexpr inline int maxi(int a, int b) noexcept
{ return ((a > b) ? a : b); }
constexpr inline int clampi(int val, int min, int max) noexcept
{ return mini(max, maxi(min, val)); }

constexpr inline int64_t mini64(int64_t a, int64_t b) noexcept
{ return ((a > b) ? b : a); }
constexpr inline int64_t maxi64(int64_t a, int64_t b) noexcept
{ return ((a > b) ? a : b); }
constexpr inline int64_t clampi64(int64_t val, int64_t min, int64_t max) noexcept
{ return mini64(max, maxi64(min, val)); }

constexpr inline uint64_t minu64(uint64_t a, uint64_t b) noexcept
{ return ((a > b) ? b : a); }
constexpr inline uint64_t maxu64(uint64_t a, uint64_t b) noexcept
{ return ((a > b) ? a : b); }
constexpr inline uint64_t clampu64(uint64_t val, uint64_t min, uint64_t max) noexcept
{ return minu64(max, maxu64(min, val)); }

constexpr inline size_t minz(size_t a, size_t b) noexcept
{ return ((a > b) ? b : a); }
constexpr inline size_t maxz(size_t a, size_t b) noexcept
{ return ((a > b) ? a : b); }
constexpr inline size_t clampz(size_t val, size_t min, size_t max) noexcept
{ return minz(max, maxz(min, val)); }


/** Find the next power-of-2 for non-power-of-2 numbers. */
inline uint32_t NextPowerOf2(uint32_t value) noexcept
{
    if(value > 0)
    {
        value--;
        value |= value>>1;
        value |= value>>2;
        value |= value>>4;
        value |= value>>8;
        value |= value>>16;
    }
    return value+1;
}

/** Round up a value to the next multiple. */
inline size_t RoundUp(size_t value, size_t r) noexcept
{
    value += r-1;
    return value - (value%r);
}


/* Define CTZ macros (count trailing zeros), and POPCNT macros (population
 * count/count 1 bits), for 32- and 64-bit integers. The CTZ macros' results
 * are *UNDEFINED* if the value is 0.
 */
#ifdef __GNUC__

#define POPCNT32 __builtin_popcount
#define CTZ32 __builtin_ctz
#if SIZEOF_LONG == 8
#define POPCNT64 __builtin_popcountl
#define CTZ64 __builtin_ctzl
#else
#define POPCNT64 __builtin_popcountll
#define CTZ64 __builtin_ctzll
#endif

#elif defined(HAVE_BITSCANFORWARD64_INTRINSIC)

inline int msvc64_popcnt32(uint32_t v)
{ return (int)__popcnt(v); }
#define POPCNT32 msvc64_popcnt32
inline int msvc64_ctz32(uint32_t v)
{
    unsigned long idx = 32;
    _BitScanForward(&idx, v);
    return (int)idx;
}
#define CTZ32 msvc64_ctz32

inline int msvc64_popcnt64(uint64_t v)
{ return (int)__popcnt64(v); }
#define POPCNT64 msvc64_popcnt64
inline int msvc64_ctz64(uint64_t v)
{
    unsigned long idx = 64;
    _BitScanForward64(&idx, v);
    return (int)idx;
}
#define CTZ64 msvc64_ctz64

#elif defined(HAVE_BITSCANFORWARD_INTRINSIC)

inline int msvc_popcnt32(uint32_t v)
{ return (int)__popcnt(v); }
#define POPCNT32 msvc_popcnt32
inline int msvc_ctz32(uint32_t v)
{
    unsigned long idx = 32;
    _BitScanForward(&idx, v);
    return (int)idx;
}
#define CTZ32 msvc_ctz32

inline int msvc_popcnt64(uint64_t v)
{ return (int)(__popcnt((uint32_t)v) + __popcnt((uint32_t)(v>>32))); }
#define POPCNT64 msvc_popcnt64
inline int msvc_ctz64(uint64_t v)
{
    unsigned long idx = 64;
    if(!_BitScanForward(&idx, (uint32_t)(v&0xffffffff)))
    {
        if(_BitScanForward(&idx, (uint32_t)(v>>32)))
            idx += 32;
    }
    return (int)idx;
}
#define CTZ64 msvc_ctz64

#else

/* There be black magics here. The popcnt method is derived from
 * https://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetParallel
 * while the ctz-utilizing-popcnt algorithm is shown here
 * http://www.hackersdelight.org/hdcodetxt/ntz.c.txt
 * as the ntz2 variant. These likely aren't the most efficient methods, but
 * they're good enough if the GCC or MSVC intrinsics aren't available.
 */
inline int fallback_popcnt32(uint32_t v)
{
    v = v - ((v >> 1) & 0x55555555u);
    v = (v & 0x33333333u) + ((v >> 2) & 0x33333333u);
    v = (v + (v >> 4)) & 0x0f0f0f0fu;
    return (int)((v * 0x01010101u) >> 24);
}
#define POPCNT32 fallback_popcnt32
inline int fallback_ctz32(uint32_t value)
{ return fallback_popcnt32(~value & (value - 1)); }
#define CTZ32 fallback_ctz32

inline int fallback_popcnt64(uint64_t v)
{
    v = v - ((v >> 1) & 0x5555555555555555_u64);
    v = (v & 0x3333333333333333_u64) + ((v >> 2) & 0x3333333333333333_u64);
    v = (v + (v >> 4)) & 0x0f0f0f0f0f0f0f0f_u64;
    return (int)((v * 0x0101010101010101_u64) >> 56);
}
#define POPCNT64 fallback_popcnt64
inline int fallback_ctz64(uint64_t value)
{ return fallback_popcnt64(~value & (value - 1)); }
#define CTZ64 fallback_ctz64
#endif


/**
 * Fast float-to-int conversion. No particular rounding mode is assumed; the
 * IEEE-754 default is round-to-nearest with ties-to-even, though an app could
 * change it on its own threads. On some systems, a truncating conversion may
 * always be the fastest method.
 */
inline int fastf2i(float f) noexcept
{
#if defined(HAVE_SSE_INTRINSICS)
    return _mm_cvt_ss2si(_mm_set_ss(f));

#elif defined(_MSC_VER) && defined(_M_IX86_FP)

    int i;
    __asm fld f
    __asm fistp i
    return i;

#elif (defined(__GNUC__) || defined(__clang__)) && (defined(__i386__) || defined(__x86_64__))

    int i;
#ifdef __SSE_MATH__
    __asm__("cvtss2si %1, %0" : "=r"(i) : "x"(f));
#else
    __asm__ __volatile__("fistpl %0" : "=m"(i) : "t"(f) : "st");
#endif
    return i;

#else

    return static_cast<int>(f);
#endif
}

/** Converts float-to-int using standard behavior (truncation). */
inline int float2int(float f) noexcept
{
#if defined(HAVE_SSE_INTRINSICS)
    return _mm_cvtt_ss2si(_mm_set_ss(f));

#elif ((defined(__GNUC__) || defined(__clang__)) && (defined(__i386__) || defined(__x86_64__)) && \
       !defined(__SSE_MATH__)) || (defined(_MSC_VER) && defined(_M_IX86_FP) && _M_IX86_FP == 0)
    int sign, shift, mant;
    union {
        float f;
        int i;
    } conv;

    conv.f = f;
    sign = (conv.i>>31) | 1;
    shift = ((conv.i>>23)&0xff) - (127+23);

    /* Over/underflow */
    if(UNLIKELY(shift >= 31 || shift < -23))
        return 0;

    mant = (conv.i&0x7fffff) | 0x800000;
    if(LIKELY(shift < 0))
        return (mant >> -shift) * sign;
    return (mant << shift) * sign;

#else

    return static_cast<int>(f);
#endif
}

/**
 * Rounds a float to the nearest integral value, according to the current
 * rounding mode. This is essentially an inlined version of rintf, although
 * makes fewer promises (e.g. -0 or -0.25 rounded to 0 may result in +0).
 */
inline float fast_roundf(float f) noexcept
{
#if (defined(__GNUC__) || defined(__clang__)) && (defined(__i386__) || defined(__x86_64__)) && \
    !defined(__SSE_MATH__)

    float out;
    __asm__ __volatile__("frndint" : "=t"(out) : "0"(f));
    return out;

#else

    /* Integral limit, where sub-integral precision is not available for
     * floats.
     */
    static constexpr float ilim[2] = {
         8388608.0f /*  0x1.0p+23 */,
        -8388608.0f /* -0x1.0p+23 */
    };
    unsigned int sign, expo;
    union {
        float f;
        unsigned int i;
    } conv;

    conv.f = f;
    sign = (conv.i>>31)&0x01;
    expo = (conv.i>>23)&0xff;

    if(UNLIKELY(expo >= 150/*+23*/))
    {
        /* An exponent (base-2) of 23 or higher is incapable of sub-integral
         * precision, so it's already an integral value. We don't need to worry
         * about infinity or NaN here.
         */
        return f;
    }
    /* Adding the integral limit to the value (with a matching sign) forces a
     * result that has no sub-integral precision, and is consequently forced to
     * round to an integral value. Removing the integral limit then restores
     * the initial value rounded to the integral. The compiler should not
     * optimize this out because of non-associative rules on floating-point
     * math (as long as you don't use -fassociative-math,
     * -funsafe-math-optimizations, -ffast-math, or -Ofast, in which case this
     * may break).
     */
    f += ilim[sign];
    return f - ilim[sign];
#endif
}

#endif /* AL_NUMERIC_H */