numeric.h

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#ifndef GEOGRAM_BASIC_NUMERIC
#define GEOGRAM_BASIC_NUMERIC
 
#include <geogram/basic/common.h>
#include <geogram/basic/assert.h>
#include <cmath>
#include <float.h>
#include <limits.h>
#include <algorithm> // for std::min / std::max
#include <stdint.h>
#include <limits>
#include <type_traits>
#include <iostream>
#include <cstdlib>
 
#ifndef M_PI
#define M_PI 3.14159265358979323846
#endif
 
namespace GEO {
 
    enum Sign {
        NEGATIVE = -1,
        ZERO = 0,
        POSITIVE = 1
    };
 
 
    template <class T>
    inline Sign geo_cmp(const T& a, const T& b) {
        return Sign((a > b) - (a < b));
    }
 
 
    template <class T>
    inline Sign geo_sgn(const T& x) {
        return geo_cmp(x, T(0));
    }
 
    namespace Numeric {
 
        typedef void* pointer;
 
        typedef int8_t int8;
 
        typedef int16_t int16;
 
        typedef int32_t int32;
 
        typedef int64_t int64;
 
        typedef uint8_t uint8;
 
        typedef uint16_t uint16;
 
        typedef uint32_t uint32;
 
        typedef uint64_t uint64;
 
        typedef float float32;
 
        typedef double float64;
 
        inline constexpr float32 max_float32() {
            return std::numeric_limits<float32>::max();
        }
 
        inline constexpr float32 min_float32() {
            // Note: numeric_limits<>::min() is not
            // what we want (it returns the smallest
            // positive non-denormal).
            return -max_float32();
        }
 
        inline constexpr float64 max_float64() {
            return std::numeric_limits<float64>::max();
        }
 
        inline constexpr float64 min_float64() {
            // Note: numeric_limits<>::min() is not
            // what we want (it returns the smallest
            // positive non-denormal).
            return -max_float64();
        }
 
        bool GEOGRAM_API is_nan(float32 x);
 
        bool GEOGRAM_API is_nan(float64 x);
 
        void GEOGRAM_API random_reset();
 
        void GEOGRAM_API random_reset(int seed);
 
        int32 GEOGRAM_API random_int32();
 
        float32 GEOGRAM_API random_float32();
 
        float64 GEOGRAM_API random_float64();
 
        template <class T, bool is_numeric>
        struct LimitsHelper : std::numeric_limits<T> {
        };
 
        template <class T>
        struct LimitsHelper<T, true> : std::numeric_limits<T> {
            static const size_t size = sizeof(T);
            static const size_t numbits = 8 * sizeof(T);
        };
 
        template <class T>
        struct Limits :
            LimitsHelper<T, std::numeric_limits<T>::is_specialized> {
        };
 
        template <class T> inline void optimize_number_representation(T& x) {
            geo_argused(x);
        }
 
        template <class T> inline Sign ratio_compare(
            const T& a_num, const T& a_denom, const T& b_num, const T& b_denom
        ) {
            if(a_denom == b_denom) {
                return Sign(geo_cmp(a_num,b_num)*geo_sgn(a_denom));
            }
            return Sign(
                geo_cmp(a_num*b_denom, b_num*a_denom) *
                geo_sgn(a_denom) * geo_sgn(b_denom)
            );
        }
    }
 
    /************************************************************************/
 
 
    template <class T>
    inline T geo_sqr(T x) {
        return x * x;
    }
 
    template <class T>
    inline void geo_clamp(T& x, T min, T max) {
        if(x < min) {
            x = min;
        } else if(x > max) {
            x = max;
        }
    }
 
    typedef geo_index_t index_t;
 
    inline constexpr index_t max_index_t() {
        return std::numeric_limits<index_t>::max();
    }
 
    typedef geo_signed_index_t signed_index_t;
 
    inline constexpr signed_index_t max_signed_index_t() {
        return std::numeric_limits<signed_index_t>::max();
    }
 
    inline signed_index_t min_signed_index_t() {
        return std::numeric_limits<signed_index_t>::min();
    }
 
    typedef geo_coord_index_t coord_index_t;
 
    inline double round(double x) {
        return ((x - floor(x)) > 0.5 ? ceil(x) : floor(x));
    }
 
    /************************************************************************/
 
    static constexpr index_t NO_INDEX = index_t(-1);
 
    /************************************************************************/
 
    template <class T> struct is_scalar {
        typedef typename std::is_arithmetic<T>::type type;
        static constexpr bool value = std::is_arithmetic<T>::value;
    };
 
    /************************************************************************/
}
 
 
/************* Disable floating point contraction **************************/
 
#if defined(GOMGEN)
#  define GEO_FP_CONTRACT_OFF(x)
#elif defined(__clang__)
#  define GEO_FP_CONTRACT_OFF _Pragma("clang fp contract(off)")
#elif defined(_MSC_VER)
#  define GEO_FP_CONTRACT_OFF _Pragma("fp_contract(off)")
#elif defined(__GNUC__)
 
// GCC does not have any pragma to deactivate FMA generation,
// so instead we check that they are deactivated (by the command-line
// option -ffp-contract=off) and fire an assertion fail if it was not
// the case.
struct GeoAssertNoFpContract {
    GeoAssertNoFpContract() {
#ifdef GEOGRAM_PSM
        if(fp_contraction_enabled()) {
            std::cerr << "Needs to be compiled with -ffp-contract-off"
                      << std::endl;
            abort();
        }
#else
        geo_assert(!fp_contraction_enabled());
#endif
    }
    static bool fp_contraction_enabled() {
        return (a2plusb(0x1.0000002p0, -0x1.0000004p0) != 0.0);
    }
    __attribute__((noipa)) static double a2plusb(double a, double b) {
        return a * a + b;
    }
};
#  define GEO_FP_CONTRACT_OFF \
    static GeoAssertNoFpContract CPP_CONCAT(assert_no_fp_contract_,__LINE__);
#else
#  define GEO_FP_CONTRACT_OFF _Pragma("STDC FP_CONTRACT OFF")
#endif
 
#endif