interval.hh

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    FAUST compiler
    Copyright (C) 2003-2004 GRAME, Centre National de Creation Musicale
    ---------------------------------------------------------------------
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    You should have received a copy of the GNU General Public License
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#ifndef __signals_intervals__
#define __signals_intervals__

#include <math.h>
#include <iostream>

#ifdef WIN32
inline double log2(double e) { return log(e)/log(double(2)); }
#endif

using namespace std;

struct interval 
{
    bool    valid;          
    double  lo;             
    double  hi;             
    
    interval ()                     : valid(false), lo(-HUGE_VAL), hi(HUGE_VAL) {}
    interval (double n)             : valid(true), lo(n), hi(n) {}
    interval (double n, double m)   : valid(true), lo(min(n,m)), hi(max(n,m)) {}
    interval (const interval& r)    : valid(r.valid), lo(r.lo), hi(r.hi) {}
    
    bool isconst() { return valid & (lo == hi); }
};

inline ostream& operator<<(ostream& dst, const interval& i)     
{ 
    if (i.valid) {
        return  dst << "interval(" << i.lo << ", " << i.hi << ")";
    } else {
        return  dst << "interval()";
    }
}

inline double min(double x, double y) { return (x<y) ? x:y; }
inline double max(double x, double y) { return (x>y) ? x:y; }
inline double min4(double a, double b, double c, double d)  { return min(min(a,b),min(c,d)); }
inline double max4(double a, double b, double c, double d)  { return max(max(a,b),max(c,d)); }

inline interval reunion(const interval& x, const interval& y)
{
    if (x.valid & y.valid) {
        return interval(min(x.lo,y.lo), max(x.hi,y.hi));
    } else {
        return interval();
    }
}


inline interval operator+(const interval& x, const interval& y)     
{ 
    return (x.valid&y.valid) ? interval(x.lo+y.lo, x.hi+y.hi) : interval(); 
}

inline interval operator-(const interval& x, const interval& y)     
{ 
    return (x.valid & y.valid) ? interval(x.lo-y.hi, x.hi-y.lo) : interval();; 
}

inline interval operator*(const interval& x, const interval& y)     
{ 
    if (x.valid&y.valid) {
        double a=x.lo*y.lo; 
        double b=x.lo*y.hi; 
        double c=x.hi*y.lo; 
        double d=x.hi*y.hi;
        return interval(min4(a,b,c,d), max4(a,b,c,d));
    } else {
        return interval();
    }
}

inline interval operator/(const interval& x, const interval& y)
{
    return (x.valid && y.valid && (y.lo > 0 | y.hi < 0)) 
            ? x * interval(1/y.hi,1/y.lo)
            : interval();
}

inline interval operator%(const interval& x, const interval& y)
{
    return (x.valid && y.valid && x.lo >= 0 && y.lo > 0) 
            ? interval(0,y.hi)
            : interval();
}

inline int bitmask (double x)   {
    int v = int(x);
    for (int i=1; i<32; i*=2)   { v |= v>>i; }
    return v;
}

//----------------------booleans&bits--------------------------------------

inline interval operator&(const interval& x, const interval& y)
{
    if (x.valid && y.valid) {
        if (x.lo >= 0 & y.lo >= 0) {
            return interval(0, bitmask(x.hi) & bitmask(y.hi));
        } else if (y.lo >= 0) {
            return interval(0, bitmask(y.hi));
        } else if (x.lo >= 0) {
            return interval(0, bitmask(y.hi));
        } else {
            return interval();
        }
    } else if (x.valid & x.lo >= 0) {
        return interval(0, bitmask(x.hi));
    } else if (y.valid & y.lo >= 0) {
        return interval(0, bitmask(y.hi));
    } else {
        return interval();
    }
}

inline interval operator|(const interval& x, const interval& y)
{
    if (x.valid && y.valid && x.lo >= 0 && y.lo >= 0) {
        return interval(0, bitmask(x.hi) | bitmask(y.hi));
    } else {
        return interval();
    }
}

inline interval operator^(const interval&, const interval&)
{
    return interval();
}

inline interval operator<<(const interval&, const interval&)
{
    return interval();
}

inline interval operator>>(const interval&, const interval&)
{
    return interval();
}

// ---------------------comparaisons------------------------------
// note : les comparaisons ne portent pas sur les intervals 
// mais l'interval des comparaisons de signaux

inline interval operator<(const interval&, const interval&)
{
    return interval(0,1);
}

inline interval operator<=(const interval&, const interval&)
{
    return interval(0,1);
}

inline interval operator>(const interval&, const interval&)
{
    return interval(0,1);
}

inline interval operator>=(const interval&, const interval&)
{
    return interval(0,1);
}

inline interval operator==(const interval&, const interval&)
{
    return interval(0,1);
}

inline interval operator!=(const interval&, const interval&)
{
    return interval(0,1);
}

//-----------------------------------------------------------------------

inline interval min(const interval& x, const interval& y)
{
    return interval(min(x.lo,y.lo), min(x.hi,y.hi));
}

inline interval max(const interval& x, const interval& y)
{
    return interval(max(x.lo,y.lo), max(x.hi,y.hi));
}

inline interval pow(const interval& x, const interval& y)
{
    if (x.lo > 0.0) {
        double a = pow(x.lo,y.lo);
        double b = pow(x.lo,y.hi);
        double c = pow(x.hi,y.lo);
        double d = pow(x.hi,y.hi);
        return interval(min4(a,b,c,d), max4(a,b,c,d));
    } else {
        return interval();
    }
}
        
inline interval abs(const interval& x)
{
    if (x.valid) {
        if (x.lo >= 0) {
            return x;
        } else if (x.hi < 0) {
            return interval(fabs(x.hi), fabs(x.lo));
        } else {
            return interval(0, max(fabs(x.lo), x.hi));
        }
    } else {
        return x;
    }
}       

#endif