/***********************************************

 !!!! DO NOT EDIT THIS FILE !!!!

 This file was auto-generated by Build.PL from
 lib/KinoSearch/Search/Similarity.pm

 See KinoSearch::Docs::DevGuide for details.

 ***********************************************/

#line 239 "lib/KinoSearch/Search/Similarity.pm"

#include "KinoSearchSearchSimilarity.h"

Similarity*
Kino_Sim_new() {
    int            i;
    unsigned char  aUChar;
    Similarity    *sim;

    Kino_New(0, sim, 1, Similarity);

    /* cache decoded norms */
    Kino_New(0, sim->norm_decoder, 256, float);
    for (i = 0; i < 256; i++) {
        aUChar = i;
        sim->norm_decoder[i] = Kino_Sim_byte2float(sim, (char)aUChar);
    }

    sim->tf    = Kino_Sim_default_tf;
    sim->coord = Kino_Sim_coord;
    return sim;
}

float
Kino_Sim_default_tf(Similarity *sim, float freq) {
    return( sqrt(freq) );
}

float
Kino_Sim_title_tf(Similarity *sim, float freq) {
    return 1.0;
}


char 
Kino_Sim_float2byte(Similarity *sim, float f) {
    char norm;
    I32  mantissa;
    I32  exponent;
    I32  bits;

    if (f < 0.0)
        f = 0.0;

    if (f == 0.0) {
        norm = 0;
    }
    else {
        bits = *(I32*)&f;
        mantissa = (bits & 0xffffff) >> 21;
        exponent = (((bits >> 24) & 0x7f)-63) + 15;

        if (exponent > 31) {
            exponent = 31;
            mantissa = 7;
        }
        if (exponent < 0) {
            exponent = 0;
            mantissa = 1;
        }
         
        norm = (char)((exponent << 3) | mantissa);
    }

    return norm;
}

float
Kino_Sim_byte2float(Similarity *sim, char b) {
    I32 mantissa;
    I32 exponent;
    I32 result;

    if (b == 0) {
        result = 0;
    }
    else {
        mantissa = b & 7;
        exponent = (b >> 3) & 31;
        result = ((exponent+(63-15)) << 24) | (mantissa << 21);
    }
    
    return *(float*)&result;
}

/* Calculate a score factor based on the number of terms which match. */
float
Kino_Sim_coord(Similarity *sim, U32 overlap, U32 max_overlap) {
    if (max_overlap == 0)
        return 1;
    return (float)overlap / (float)max_overlap;
}

void
Kino_Sim_destroy(Similarity *sim) {
    Kino_Safefree(sim->norm_decoder);
    Kino_Safefree(sim);
}