//  *************** HEAP.C *********************

// Fixed Block Memory manager 

// Global structures of Fixed Block Memory manager 

// The "Heap" is the statically allocated memory to be managed 

// Last modified 1/16/03 by Jonathan W. Valvano

 

// Copyright 2003 by Jonathan W. Valvano, valvano@uts.cc.utexas.edu 

//    You may use, edit, run or distribute this file 

//    as long as the above copyright notice remains 



unsigned short Heap[BLOCKSIZE*NUMBLOCKS];   

unsigned short *FreePt;    // Pointer the first free block 

void Heap_Init(void){ unsigned short *pt;

  FreePt = &Heap[0];

  for(pt=&Heap[0];pt!=&Heap[BLOCKSIZE*(NUMBLOCKS-1)];pt=pt+BLOCKSIZE){

    *pt = (unsigned short)pt+2*BLOCKSIZE;   /* Create linked list */

  }

  *pt = null;

}

/* Returns a pointer to a memory block of "BLOCKSIZE" integers 

   The returned pointer will be null (0) if the Heap is empty */

unsigned short *Heap_Allocate(void){ unsigned short *pt;

  pt = FreePt;

  if(pt!=null){ 

    FreePt = (unsigned short*)*pt;

  }

  return(pt);

}



/* Releases the memory block of "BLOCKSIZE" integers pointed to by "pt"

   No protection, we assume "pt" points to a previously allocated block */

void Heap_Release(unsigned short *pt){ unsigned short *oldFreePt;

  oldFreePt = FreePt;

  FreePt = pt;

  *pt = (unsigned short)oldFreePt; 

}