#include <stdio.h>          // for printf()
#include <stdlib.h>         // for malloc(), free(), rand(), srand()
#include <stddef.h>         // for size_t, ptrdiff_t
#include <stdbool.h>        // for typedef bool

//-- print matrix --------------------------------------------------------------

// general matrix
void
printDGeMatrix(size_t m, size_t n,
               const double *A,
               ptrdiff_t incRowA, ptrdiff_t incColA)
{
    for (size_t i=0; i<m; ++i) {
        for (size_t j=0; j<n; ++j) {
            printf("%9.2lf ", A[i*incRowA + j*incColA]);
        }
        printf("\n");
    }
    printf("\n");
}

void
printIGeMatrix(size_t m, size_t n,
               const size_t *A,
               ptrdiff_t incRowA, ptrdiff_t incColA)
{
    for (size_t i=0; i<m; ++i) {
        for (size_t j=0; j<n; ++j) {
            printf("%6zu ", A[i*incRowA + j*incColA]);
        }
        printf("\n");
    }
    printf("\n");
}

//-- required BLAS functions: daxpy, ddot, dtrsv -------------------------------

void
dswap(size_t n, double *x, ptrdiff_t incX, double *y, ptrdiff_t incY)
{
    for (size_t i=0; i<n; ++i) {
        double tmp = x[i*incX];
        x[i*incX] = y[i*incY];
        y[i*incY] = tmp;
    }
}

void
dlaswp(size_t n, size_t k0, size_t k1,
       const size_t *p, ptrdiff_t incP,
       double *A, ptrdiff_t incRowA, ptrdiff_t incColA)
{
    /* your code here */
}

//-- simple test program -------------------------------------------------------

#ifndef COLMAJOR
#define COLMAJOR 1
#endif

int
main()
{
    printf("COLMAJOR = %d\n", COLMAJOR);

    size_t      m       = 6;
    size_t      n       = 2;
    ptrdiff_t   incRowA = COLMAJOR ? 1 : n;
    ptrdiff_t   incColA = COLMAJOR ? m : 1;
    double      *A      = malloc(m*n*sizeof(double));

    size_t      k       = 4;
    ptrdiff_t   incP    = 1;
    size_t      *p      = malloc(k*sizeof(size_t));

    if (!A || !p) {
        abort();
    }

    // init A
    for (size_t j=0; j<n; ++j) {
        for (size_t i=0; i<m; ++i) {
            A[i*incRowA + j*incColA] =   i*n + j + 1;
        }
    }

    // init p handish (only elements with index between k0 and k1 are usable)
    size_t k0 = 2;
    size_t k1 = 3;

    p[0*incP] = -1;  // <- illegal pivot
    p[1*incP] = -1;  // <- illegal pivot
    p[2*incP] = 5;
    p[3*incP] = 4;

    printf("A =\n");
    printDGeMatrix(m, n, A, incRowA, incColA);

    printf("p =\n");
    printIGeMatrix(1, k, p, 0, incP);

    printf("dlaswp with k0 = %zu, k1 = %zu\n", k0, k1);
    dlaswp(n, k0, k1, p, incP, A, incRowA, incColA);

    printf("A =\n");
    printDGeMatrix(m, n, A, incRowA, incColA);

    printf("dlaswp with k0 = %zu, k1 = %zu\n", k1, k0);
    dlaswp(n, k1, k0, p, incP, A, incRowA, incColA);

    printf("A =\n");
    printDGeMatrix(m, n, A, incRowA, incColA);

    free(A);
    free(p);
}