/*

File:  Time.c

Abstract:

    This program times some cases of the vAdd routine.  It illustrates the

    execution speed of the sample routine but is not otherwise needed to

    understand the lessons of the session.

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*/

#include <stdio.h>

#include <stdlib.h>

#include "ClockServices.h"

#include "vAdd.h"

#define ElementsPerVector   4

// Define a structure to hold parameters needed by the routine being timed.

typedef struct { const float *A; const float *B; float *C; long N; } Parameters;

// Driver is a routine that calls the subject routine repeatedly.

void Driver(unsigned int iterations, void *data)

{

    // Get the parameters from the structure passed to us.

    Parameters *parameters = (Parameters *) data;

    const float *A  = parameters->A;

    const float *B  = parameters->B;

          float *C  = parameters->C;

    long N = parameters->N;

    // Call the subject routine the number of times requested.

    while (iterations--)

        vAdd(A, B, C, N);

}

int main(void)

{

    // Define test data.

    static const int N = 1024;

    int AllocationLength = N + ElementsPerVector - 1;

    /*  Allocate space for arrays.  Include extra space so we can perform

        measurements with different address offsets.

    */

    float *A = malloc(AllocationLength * sizeof *A);

    float *B = malloc(AllocationLength * sizeof *B);

    float *C = malloc(AllocationLength * sizeof *C);

    if (!A || !B || !C)

    {

        free(C);

        free(B);

        free(A);

        fprintf(stderr, "Error, failed to allocate memory.\n");

        return EXIT_FAILURE;

    }

    // Initialize input arrays.

    for (long i = 0; i < AllocationLength; ++i)

    {

        A[i] = i;

        B[i] = 10000 * i;

    }

    // Print table header.

    printf("Offset in Bytes\n");

    printf("   A    B    C    CPU Cycles Per Element\n");

    for (long AOffset = 0; AOffset < ElementsPerVector; ++AOffset)

    for (long BOffset = 0; BOffset < ElementsPerVector; ++BOffset)

    for (long COffset = 0; COffset < ElementsPerVector; ++COffset)

    {

        // Package parameters for timing routine.

        Parameters parameters = { A + AOffset, B + BOffset, C + COffset, N };

        // Measure the execution time of the subject routine.

        double t = MeasureNetTimeInCPUCycles(Driver, 100, &parameters, 100);

        printf("%4zd %4zd %4zd    %.3g\n",

            AOffset * sizeof *A, BOffset * sizeof *B, COffset * sizeof *C,

            t / N);

    }

    free(C);

    free(B);

    free(A);

    return 0;

}