/************************************************************************
 
 This example uses _ucreate to create an expandable heap. The functions for expanding and 
 shrinking the heap are get_fn and release_fn. The program then opens the heap and 
 performs operations on it, and then closes and destroys the heap. 

 ************************************************************************/
 
 

 #define  INCL_DOSMEMMGR             /* Memory Manager values */
 #include <os2.h>
 #include <bsememf.h>                /* Get flags for memory management  */
 #include <stdlib.h>
 #include <stdio.h>
 #include <umalloc.h>
 
 static void * _Optlink get_fn(Heap_t usrheap, size_t *length, int *clean)
 {
    void *p;
    int rc;

    /* Round up to the next chunk size */
    *length = ((*length) / 65536) * 65536 + 65536;
    *clean = _BLOCK_CLEAN;
    rc = DosAllocMem(&p, *length, PAG_COMMIT | PAG_READ | PAG_WRITE  | OBJ_ANY  );
    if(rc)
    {  printf("DosAllocMem rc =%i\n",rc);
       exit(1);
    } 

    return (p);
 }
 
 static void _Optlink  release_fn(Heap_t usrheap, void *p, size_t size)
 {
    DosFreeMem(p);
    return;
 }
 
 int main(void)
 {
    void    *initial_block;
    APIRET  rc;
    Heap_t  myheap;
    char    *ptr;
    int iRAM,i; 
    
    /* Call DosAllocMem to get the initial block of memory */
    if (0 != (rc = DosAllocMem(&initial_block, 65536,
                               PAG_WRITE | PAG_READ | PAG_COMMIT))) {
       printf("DosAllocMem error: return code = %ld\n", rc);
       exit(EXIT_FAILURE);
    }
    /* Create an expandable heap starting with the block declared earlier */
    if (NULL == (myheap = _ucreate(initial_block, 65536, _BLOCK_CLEAN,
                                   _HEAP_REGULAR, get_fn, release_fn))) {
       puts("_ucreate failed.");
       exit(EXIT_FAILURE);
    }
    if (0 != _uopen(myheap)) {
       puts("_uopen failed.");
       exit(EXIT_FAILURE);
    }
    iRAM = 0;
/* кушаем 1Гб */
    for(i=0;i<1024;i++)
    {  
    /* Force user heap to grow */
       ptr = (char *)_umalloc(myheap, 1024*1024);
       iRAM += 1;
       printf("RAM eat:%iMb\n",iRAM);
    }   
/* пишем в файл */
   {  FILE *fp;
      fp = fopen("test.tst","wb");
      for(i=0;i<1024;i++) ptr[i] = (i&0xff);
      rc = fwrite(ptr,1024,1,fp);
      printf("fwrite rc=%i\n",rc);  
      fclose(fp);
      fp = fopen("test.tst","rb");
      rc = fread(ptr,1024,1,fp);
      printf("fread rc=%i\n",rc);  
      for(i=0;i<1024;i++) 
      {  if(ptr[i]!= (i&0xff))
         {   printf("%i ptr=%i != %i\n",i,ptr[i],(i&0xff));
         }  
      }
  
      fclose(fp);
   }  
    _uclose(myheap);
 
    if (0 != _udestroy(myheap, _FORCE)) {
       puts("_udestroy failed.");
       exit(EXIT_FAILURE);
    }
    if (0 != (rc = DosFreeMem(initial_block))) {
       printf("DosFreeMem error: return code = %ld\n", rc);
       exit(EXIT_FAILURE);
    }
    return 0;
 }