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ca815af077
Change the isxxx functions to correctly handle values outside of character range. git-svn-id: svn://svn.cc65.org/cc65/trunk@33 b7a2c559-68d2-44c3-8de9-860c34a00d81
108 lines
2.7 KiB
C
108 lines
2.7 KiB
C
/*
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* _hadd.c
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*
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* Ullrich von Bassewitz, 19.06.1998
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*/
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#include <stddef.h>
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#include "_heap.h"
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void _hadd (void* mem, size_t size)
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/* Add an arbitrary memory block to the heap. This function is used by
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* free(), but it does also allow usage of otherwise unused memory
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* blocks as heap space. The given block is entered in the free list
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* without any checks, so beware!
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*/
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{
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struct freeblock* f;
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struct freeblock* left;
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struct freeblock* right;
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if (size >= sizeof (struct freeblock)) {
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/* Set the admin data */
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f = (struct freeblock*) mem;
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f->size = size;
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/* Check if the freelist is empty */
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if (_hfirst == 0) {
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/* The freelist is empty until now, insert the block */
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f->prev = 0;
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f->next = 0;
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_hfirst = f;
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_hlast = f;
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} else {
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/* We have to search the free list. As we are doing so, we check
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* if it is possible to combine this block with another already
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* existing block. Beware: The block may be the "missing link"
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* between *two* other blocks.
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*/
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left = 0;
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right = _hfirst;
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while (right && f > right) {
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left = right;
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right = right->next;
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}
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/* Ok, the current block must be inserted between left and right (but
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* beware: one of the two may be zero!). Also check for the condition
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* that we have to merge two or three blocks.
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*/
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if (right) {
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/* Check if we must merge the block with the right one */
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if (((unsigned) f) + size == (unsigned) right) {
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/* Merge with the right block */
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f->size += right->size;
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if (f->next = right->next) {
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f->next->prev = f;
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} else {
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/* This is now the last block */
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_hlast = f;
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}
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} else {
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/* No merge, just set the link */
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f->next = right;
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right->prev = f;
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}
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} else {
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f->next = 0;
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/* Special case: This is the new freelist end */
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_hlast = f;
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}
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if (left) {
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/* Check if we must merge the block with the left one */
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if ((unsigned) f == ((unsigned) left) + left->size) {
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/* Merge with the left block */
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left->size += f->size;
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if (left->next = f->next) {
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left->next->prev = left;
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} else {
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/* This is now the last block */
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_hlast = left;
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}
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} else {
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/* No merge, just set the link */
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left->next = f;
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f->prev = left;
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}
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} else {
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f->prev = 0;
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/* Special case: This is the new freelist start */
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_hfirst = f;
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}
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}
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}
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}
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