36 lines
995 B
C
36 lines
995 B
C
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// system function calls
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#include <sys/types.h> // provides caddr_t /* for caddr_t (typedef char * caddr_t;) */s
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#ifdef __cplusplus
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extern "C" {
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#endif
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/* Excellent insight from Martin T. https://embdev.net/topic/linker-error-undefined-reference-to-_sbrk */
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static unsigned char* _eheap = NULL; // our heap management tracks the end of the heap with this var
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extern unsigned char _sheap; // Provided by linker
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caddr_t _sbrk ( int incr ){
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unsigned char* prev_heap;
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unsigned char local;
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// Initialize the heap pointer
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if (_eheap == NULL) {
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_eheap = (unsigned char*)&_sheap;
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}
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prev_heap = _eheap;
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// Check that the requested amount of memory is available (w/ margin)
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if( ((&local)-(_eheap)) >= (incr + 128) ){
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_eheap += incr;
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}else{
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// set errno to ENOMEM
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prev_heap = (unsigned char*)-1;
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}
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// Return the previous heap (or the error code)
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return (caddr_t) prev_heap;
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}
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#ifdef __cplusplus
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}
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#endif
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