Eight Queens

#include <stdio.h>
#include <stdlib.h>
#include<string.h>
#include<process.h>
#include "hr_time.h"

#define BHAND(op)\
{\
int s;\
for( s = 0; s < n; ++s ){\
    op (board[i + s * n ]);\
}\
for( s = 0; s < n; ++s ){\
    op (board[ s + j * n ]);\
}\
for( s = 1; (i - s >= 0) && (j - s >= 0); ++s ){\
    op (board[ ( i - s ) + ( j - s ) * n ]);\
}\
for( s = 1; (i + s < n) && (j - s >= 0); ++s ){\
    op (board[ ( i + s ) + ( j - s ) * n ]);\
}\
for( s = 1; (i - s >= 0) && (j + s < n); ++s ){\
    op (board[ ( i - s ) + ( j + s ) * n ]);\
}\
for( s = 1; (i + s < n) && (j + s < n); ++s ){\
    op (board[ ( i + s ) + ( j + s ) * n ]);\
}\
}
HANDLE hIOMutex= CreateMutex (NULL, FALSE, NULL);
int w = 0;
int solutions = 0;
int wp = 0;
int pending = 0;

_stdcall unsigned getsols( void* s ){

    int ypos = ((int*)s)[1];
    int n = ((int*)s)[0];
    int boardsize = n * n * sizeof( int );
    int* board = (int*) malloc( boardsize );
    memset( board, 0, boardsize );
    int* boardb = (int*) malloc( boardsize );
    int* stack = (int*) malloc( ( n + 1 ) * sizeof( int ) );
    *stack = -1;
    stack++;
    *stack = 0;
    int t = 1;
    int i = 0;
    int sols = 0;

    int j = ypos;
    BHAND(++);

    while( *stack != -1 ){
        for( i = 1; i < n; ++i )
        {
            j = 0;
            if( t == 0 ){
                --stack;
                if(*stack == -1)
                    break;
                i = (*stack & 0xFFFF);
                j = ((*stack >> 16) & 0xFFFF);
                //printf("Pop Stack: %i, %i \n", i, j );
                BHAND(--);
                ++j;
            }
            t = 0;
            for( ; j < n; ++j )
            {
                if( board[ i + j * n ] == 0 ){
                    BHAND(++);
                    *stack = (i & 0xFFFF) | ( (j & 0xFFFF) << 16 );
                    //printf("Push Stack: %i, %i = %i, %i\n", i, j, *stack, (i & 0xFFFF) + ( (j & 0xFFFF) << 16 ) );
                    ++stack;
                    *stack = 0;
                    t = 1;
                    break;
                }
            }
        }
        if( i == n  ){
            int* stackt = stack;
            --stack;


            int x,y;
            int queens = 0;
            while( *stack != -1 ){
                ++queens;
                x = (*stack & 0xFFFF);
                y = ((*stack >> 16) & 0xFFFF);
                --stack;
            }
            if( queens == n-1 ){
                //!Board Display
                //putchar('\n');
                /*for( int j = 0; j < n; ++j ){
                    for( int i = 0; i < n; ++i ){
                        //printf( "+-" );
                    }
                    //printf("+\n");
                    for( int i = 0; i < n; ++i ){
                        //printf( "|%c", boardb[i + j * n] == 0 ? ' ' : 'Q' );
                    }
                    //printf("|\n");
                }
                for( int i = 0; i < n; ++i ){
                    //printf( "+-" );
                }
                //printf("+\n");*/
                //while( w == 1 ){w=1;}
                //w = 1;
                ++sols;
            }
            stack = stackt;

        }
    }
    WaitForSingleObject( hIOMutex, INFINITE );
    solutions += sols;
    ReleaseMutex( hIOMutex);
}

int main(){

    int n = 8;
    printf("N? ");
    scanf("%i", &n);
    int *passin = (int*)malloc( 3 * sizeof(int) * n );
    HANDLE* threads = (HANDLE*) malloc( sizeof(HANDLE)*n);

    CStopWatch s;
    s.startTimer();
    for( int i = 0; i < n; i ++ ){
        passin[i * 2] = n;
        passin[i * 2 + 1] = i;

        threads[i] = (HANDLE)_beginthreadex( 0, 1000, getsols, passin+(i*2), 0, 0 );

    }
    WaitForMultipleObjects(n, threads, true, INFINITE);

    s.stopTimer();
    printf("Total solutions found: %i\nTime taken: %f ", solutions, s.getElapsedTime() );
    getchar();
    getchar();

}