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//

//      bitmap_c.c      The C versions of the bit-level routines

//



// defines



// Variables



int cmap_width;                 // Size of this map

int cmap_height;

int cmap_wxh;                   // Width x Height for speed





// Functions



void SetBit_C(int x,int y,char *collision_map);

void ResetBit_C(int x,int y,char *collision_map);

int GetBit_C(int x,int y,char *collision_map);



// Code





/*

 *      SetBit_C - Set the appropriate bit in the collision map

 */



void SetBit_C(int x,int y,char *collision_map)

{

int bitmap_pos;

unsigned char bitmask;



bitmap_pos = (y*cmap_width) + (x>>3);

bitmask = 1<<((unsigned char)x&7);

collision_map[bitmap_pos] |= bitmask;

}



/*

 *      ResetBit_C - Reset the appropriate bit in the collision map

 */



void ResetBit_C(int x,int y,char *collision_map)

{

int bitmap_pos;

unsigned char bitmask;



bitmap_pos = (y*cmap_width) + (x>>3);

bitmask = (1<<((unsigned char)x&7))^0xff;

collision_map[bitmap_pos] &= bitmask;

}



/*

 *      GetBit_C - Get the appropriate bit in the collision map

 */



int GetBit_C(int x,int y,char *collision_map)

{

int bitmap_pos;

unsigned char bitmask;



bitmap_pos = (y*cmap_width) + (x>>3);

bitmask = 1<<((unsigned char)x&7);

return (collision_map[bitmap_pos] & bitmask);

}