/* Memory2.cpp */
/* Heap managment for HiMemory */

 #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 int UseHiMemory = 0;
static Heap_t myheap;
static void  *initial_block;

void * _mesa2_malloc(size_t bytes);
void * _mesa2_calloc(size_t num, size_t bytes);
void * _mesa0_malloc(size_t bytes);
void * _mesa0_calloc(size_t num, size_t bytes);

void * (* _pmesa_malloc)(size_t bytes)             = _mesa0_malloc;
void * (* _pmesa_calloc)(size_t num, size_t bytes) = _mesa0_calloc;

void * _mesa0_malloc(size_t bytes)
{  return malloc(bytes);
}

void * _mesa0_calloc(size_t num, size_t bytes)
{  return calloc(num, bytes);
}

void * _mesa2_malloc(size_t bytes)
{  return _umalloc(myheap, bytes);
}

void * _mesa2_calloc(size_t num, size_t bytes)
{  return _ucalloc(myheap, num, bytes);
}

//add memory block to heap
 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);
 }

//release memory block from heap
static void _Optlink  release_fn(Heap_t usrheap, void *p, size_t size)
{   DosFreeMem(p);
   return;
}

static void  _Optlink destroy_fn(void)
{ int rc;
    _uclose(myheap);

    if (0 != _udestroy(myheap, _FORCE)) {
       puts("_udestroy failed.");
//       exit(EXIT_FAILURE);
    }
    rc = DosFreeMem(initial_block);
    if (0 != rc)
    {
       printf("DosFreeMem error: return code = %ld\n", rc);
    }
}


int InitHiMemory(void)
{
    APIRET  rc;
    char    *ptr;

    /* Call DosAllocMem to get the initial block of memory */
    if (0 != (rc = DosAllocMem(&initial_block, 65536,
                               PAG_WRITE | PAG_READ | PAG_COMMIT| OBJ_ANY))) {
       UseHiMemory = 0;
//detect presence of High Memory/old kernels
       return 1;
    }
    UseHiMemory = 1;
    _pmesa_malloc = _mesa2_malloc;
    _pmesa_calloc = _mesa2_calloc;

    /* 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))) {
       return 2;
//       puts("_ucreate failed.");
//       exit(EXIT_FAILURE);
    }
    if (0 != _uopen(myheap)) {
       return 3;
//       puts("_uopen failed.");
//       exit(EXIT_FAILURE);
    }
    atexit(destroy_fn);

    return 0;
}