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66 lines
1.4 KiB
C
66 lines
1.4 KiB
C
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/*
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* free.c
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*
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* Ullrich von Bassewitz, 11.08.1998
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*/
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#include <stdlib.h>
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#include "_heap.h"
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void free (void* block)
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/* Release an allocated memory block. The function will accept NULL pointers
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* (and do nothing in this case).
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*/
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{
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unsigned* b;
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unsigned size;
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struct freeblock* f;
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/* Allow NULL arguments */
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if (block == 0) {
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return;
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}
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/* Get a pointer to the real memory block, then get the size */
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b = (unsigned*) block;
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size = *--b;
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/* Check if the block is at the top of the heap */
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if (((int) b) + size == (int) _hptr) {
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/* Decrease _hptr to release the block */
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_hptr = (unsigned*) (((int) _hptr) - size);
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/* Check if the last block in the freelist is now at heap top. If so,
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* remove this block from the freelist.
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*/
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if (f = _hlast) {
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if (((int) f) + f->size == (int) _hptr) {
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/* Remove the last block */
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_hptr = (unsigned*) (((int) _hptr) - f->size);
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if (_hlast = f->prev) {
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/* Block before is now last block */
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f->prev->next = 0;
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} else {
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/* The freelist is empty now */
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_hfirst = 0;
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}
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}
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}
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} else {
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/* Not at heap top, enter the block into the free list */
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_hadd (b, size);
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}
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}
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