#include <testError.h>

#include "half.h"

#include <iostream>

#include <stdlib.h>

#include <assert.h>

using namespace std;

namespace {

float

drand()

{

    return static_cast<float> (rand()/(RAND_MAX+1.0f));

}

} // namespace

void

testNormalizedConversionError()

{

    cout << "float-to-half conversion error for normalized half numbers\n";

    float eMax = 0;

    for (int i = 0; i < 20000000; i++)

    {

	float f (drand() * HALF_MAX);

	if (f < HALF_NRM_MIN)

	    continue;

	if (i & 1)

	    f = -f;

	half h (f);

	float e = 1.0f - h/f;

	if (e < 0)

	    e = -e;

	if (e > HALF_EPSILON * 0.5)

	{

	    cout << "float = " << f <<

		    ", half = " << h <<

		    ", error = " << e << endl;

	    assert (false);

	}

	if (e > eMax)

	    eMax = e;

    }

    cout << "max error          = " << eMax << endl;

    cout << "max expected error = " << HALF_EPSILON * 0.5 << endl;

    cout << "ok\n\n" << flush;

}

void

testDenormalizedConversionError()

{

    cout << "float-to-half conversion error for denormalized half numbers\n";

    float eMax = 0;

    for (int i = 0; i < 20000000; i++)

    {

	float f (drand() * (HALF_NRM_MIN - HALF_MIN));

	if (i & 1)

	    f = -f;

	half h (f);

	float e = h - f;

	if (e < 0)

	    e = -e;

	if (e > HALF_MIN * 0.5)

	{

	    cout << "float = " << f <<

		    ", half = " << h <<

		    ", error = " << e << endl;

	    assert (false);

	}

	if (e > eMax)

	    eMax = e;

    }

    cout << "max error          = " << eMax << endl;

    cout << "max expected error = " << HALF_MIN * 0.5 << endl;

    cout << "ok\n\n" << flush;

}

namespace {

void

testNormalizedRounding (int n)

{

    cout << "rounding normalized numbers to " << n << "-bit precision\n";

    float eExpected = (n < 10)? HALF_EPSILON * 0.5f * (1 << (10 - n)): 0;

    float eMax = 0;

    for (int i = 0; i < 200000; i++)

    {

	half h (drand() * HALF_MAX);

	if (h < HALF_NRM_MIN)

	    continue;

	if (i & 1)

	    h = -h;

	half r (h.round(n));

	float e = 1.0f - r/h;

	if (e < 0)

	    e = -e;

	if (e > eExpected)

	{

	    cout << "half = " << h <<

		    ", rounded = " << r <<

		    ", error = " << e <<

		    ", expected error = " << eExpected << endl;

	    printBits (cout, h);

	    cout << endl;

	    printBits (cout, r);

	    cout << endl;

	    assert (false);

	}

	if (e > eMax)

	    eMax = e;

    }

    cout << "max error          = " << eMax << endl;

    cout << "max expected error = " << eExpected << endl;

    cout << "ok\n\n" << flush;

}

void

testDenormalizedRounding (int n)

{

    cout << "rounding denormalized numbers to " << n << "-bit precision\n";

    float eExpected = (n < 10)? HALF_MIN * 0.5f * (1 << (10 - n)): 0;

    float eMax = 0;

    for (int i = 0; i < 200000; i++)

    {

	half h (drand() * (HALF_NRM_MIN - HALF_MIN));

	if (i & 1)

	    h = -h;

	half r (h.round(n));

	float e = r - h;

	if (e < 0)

	    e = -e;

	if (e > eExpected)

	{

	    cout << "half = " << h <<

		    ", rounded = " << r <<

		    ", error = " << e <<

		    ", expected error = " << eExpected << endl;

	    printBits (cout, h);

	    cout << endl;

	    printBits (cout, r);

	    cout << endl;

	    assert (false);

	}

	if (e > eMax)

	    eMax = e;

    }

    cout << "max error          = " << eMax << endl;

    cout << "max expected error = " << eExpected << endl;

    cout << "ok\n\n" << flush;

}

} // namespace

void

testRoundingError ()

{

    testNormalizedRounding (10);

    testDenormalizedRounding (10);

    testNormalizedRounding (9);

    testDenormalizedRounding (9);

    testNormalizedRounding (1);

    testDenormalizedRounding (1);

    testNormalizedRounding (0);

    testDenormalizedRounding (0);

}