minmax.c

-- minmax.h
float max_ss(float a, float b);
float min_ss(float a, float b);

double max_sd(double a, double b);
double min_sd(double a, double b);

float clamp_ss(float x, float mn, float mx);
double clamp_sd(double x, double mn, double mx);

-- minmax.c
#include "minmax.h"
#include <xmmintrin.h>
#include <emmintrin.h>

inline float max_ss(float a, float b) {
    _mm_store_ss(&a, _mm_max_ss(_mm_set_ss(a), _mm_set_ss(b)));
    return a;
}

inline float min_ss(float a, float b) {
    _mm_store_ss(&a, _mm_min_ss(_mm_set_ss(a), _mm_set_ss(b)));
    return a;
}

inline double max_sd(double a, double b) {
    _mm_store_sd(&a, _mm_max_sd(_mm_set_sd(a), _mm_set_sd(b)));
    return a;
}

inline double min_sd(double a, double b) {
    _mm_store_sd(&a, _mm_min_sd(_mm_set_sd(a), _mm_set_sd(b)));
    return a;
}

inline float clamp_ss(float x, float mn, float mx) {
    _mm_store_ss(&x, _mm_min_ss(_mm_max_ss(_mm_set_ss(x),
        _mm_set_ss(mn)), _mm_set_ss(mx)));
    return x;
}

inline double clamp_sd(double x, double mn, double mx) {
    _mm_store_sd(&x, _mm_min_sd(_mm_max_sd(_mm_set_sd(x),
        _mm_set_sd(mn)), _mm_set_sd(mx)));
    return x;
}

-- MinMax.hs
{-# LANGUAGE ForeignFunctionInterface, CPP #-}

module MinMax (
    max_ss, min_ss,
    max_sd, min_sd,
    clamp_ss, clamp_sd
) where

import Foreign
import Foreign.C.Types

#define FFI_MM(name,cname,ty) \
foreign import ccall unsafe "minmax.c name" cname :: ty -> ty -> ty ;\
name :: RealFloat a => a -> a -> a                                  ;\
name a b = realToFrac $ cname (realToFrac a) (realToFrac b)         ;\
{-# INLINE cname #-}                                                ;\
{-# INLINE name #-}

FFI_MM(max_ss,c_max_ss,CFloat)
FFI_MM(min_ss,c_min_ss,CFloat)
FFI_MM(max_sd,c_max_sd,CDouble)
FFI_MM(min_sd,c_min_sd,CDouble)


#define FFI_CLAMP(name,cname,ty) \
foreign import ccall unsafe "minmax.c name" cname :: ty -> ty -> ty -> ty ;\
name :: RealFloat a => a -> a -> a -> a                                   ;\
name mn mx x = realToFrac $                                                \
    cname (realToFrac x) (realToFrac mn) (realToFrac mx)                  ;\
{-# INLINE cname #-}                                                      ;\
{-# INLINE name #-}

FFI_CLAMP(clamp_ss,c_clamp_ss,CFloat)
FFI_CLAMP(clamp_sd,c_clamp_sd,CFloat)