Shuffle.cpp

#include "Headers.h"
#include "Shuffle.h"
#include "Rand.h"

CShuffle::CShuffle(
    __uint32    count
    )
{
    assert(count);

    this->count = count;

    this->mapping = new __uint32[this->count];
    assert(this->mapping);

    for(__uint32 index = 0; index < this->count; index++)
        this->mapping[index] = index;

    this->Shuffle();
}

CShuffle::~CShuffle()
{
    delete[] this->mapping;
}

void CShuffle::Shuffle()
{
    /*
     * Portions of this code are based on: http://benpfaff.org/writings/clc/shuffle.html (last updated 04 Apr 2004 16:19)
     * Copyright � 2004 Ben Pfaff.
     */

    __uint32 i2;
    __uint32 tmp;
    
    for(__uint32 i1 = 0; i1 < this->count - 1; i1++)
    {
        i2 = i1 + CRand::Generate(this->count - i1);
        assert(i2 < this->count);

        tmp = this->mapping[i2];
        this->mapping[i2] = this->mapping[i1];
        this->mapping[i1] = tmp;
    }
}