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Accessing .sysmem ?

Imran Khan68504
Intellectual 550 points

Hi guys,

I am trying to write my own pool allocation program that allocates blocks of memory for my processes. I understand that the heap section (.sysmem) can be set at build time. Now my question is how do I access this heap with my code so I can use that memory and allocate it for my processes? I am using the LM3S9D92 and its heap/SRAM starts at 0x2000.0000. Also this is for CCSv4.

  • 0
    TI__Guru* 84225 points

    You'll need to replace the heap functions in the RTS library.  Look at the file memory.c in the source code for the RTS.  It uses special linker-defined symbols to find the beginning and end of the heap.  You should be able use the same expressions in your heap manager.  The symbols you are looking for are:

    _sys_memory
__TI_SYSMEM_SIZE
    

    
			
    

		
		
		
		
	
    
	
    
		
    
	
    

	            
                 	
	
    
				
		                
                
                
                
                
                
                
        		
		
				
    
		
		 
		
		
     
    
	
    

    
			
    
			
    
		
    

		
    
	
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						in reply to Archaeologist
					
									
    
	
    
	                                    
                      
    
                        
                          Intellectual
                        550 points
                      
    
                          
                   		
		
    
					
    Hi,
    

    

    what worked for me is:
    

    extern void * _sys_memory;         // Start of heap
    extern int __SYSMEM_SIZE;    // Size of heap

    ... and later ... 

    uint32_t* Heap = (uint32_t *)(&_sys_memory);
    uint32_t* HeapEnd = (uint32_t *)(&__SYSMEM_SIZE);
         
    HeapEnd = (uint32_t *)((uint32_t)Heap + (uint32_t)HeapEnd);
    

    

    (it would recognize _sys_memory but not __TI_SYSTEM_SIZE)
    

    

    thank you for pointing me in the right direction
    

    Imran
    
			
    

		
		
		
		
	
    
	
    
		
    
	
    

	            
                	
	
    
				
		                
                
                
                
                
                
                
        		
		
				
    
		
		 
		
		
     
    
	
    

    
			
    
			
    
		
    

		
    
	
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