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-rw-r--r--Build/source/libs/gd/libgd-src/src/gdcache.h88
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diff --git a/Build/source/libs/gd/libgd-src/src/gdcache.h b/Build/source/libs/gd/libgd-src/src/gdcache.h
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+++ b/Build/source/libs/gd/libgd-src/src/gdcache.h
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+#ifdef __cplusplus
+extern "C" {
+#endif
+
+ /*
+ * gdcache.h
+ *
+ * Caches of pointers to user structs in which the least-recently-used
+ * element is replaced in the event of a cache miss after the cache has
+ * reached a given size.
+ *
+ * John Ellson (ellson@graphviz.org) Oct 31, 1997
+ *
+ * Test this with:
+ * gcc -o gdcache -g -Wall -DTEST gdcache.c
+ *
+ * The cache is implemented by a singly-linked list of elements
+ * each containing a pointer to a user struct that is being managed by
+ * the cache.
+ *
+ * The head structure has a pointer to the most-recently-used
+ * element, and elements are moved to this position in the list each
+ * time they are used. The head also contains pointers to three
+ * user defined functions:
+ * - a function to test if a cached userdata matches some keydata
+ * - a function to provide a new userdata struct to the cache
+ * if there has been a cache miss.
+ * - a function to release a userdata struct when it is
+ * no longer being managed by the cache
+ *
+ * In the event of a cache miss the cache is allowed to grow up to
+ * a specified maximum size. After the maximum size is reached then
+ * the least-recently-used element is discarded to make room for the
+ * new. The most-recently-returned value is always left at the
+ * beginning of the list after retrieval.
+ *
+ * In the current implementation the cache is traversed by a linear
+ * search from most-recent to least-recent. This linear search
+ * probably limits the usefulness of this implementation to cache
+ * sizes of a few tens of elements.
+ */
+
+ /*********************************************************/
+ /* header */
+ /*********************************************************/
+
+#include <stdlib.h>
+#ifndef NULL
+# define NULL (void *)0
+#endif
+
+ /* user defined function templates */
+ typedef int (*gdCacheTestFn_t)(void *userdata, void *keydata);
+ typedef void *(*gdCacheFetchFn_t)(char **error, void *keydata);
+ typedef void (*gdCacheReleaseFn_t)(void *userdata);
+
+ /* element structure */
+ typedef struct gdCache_element_s gdCache_element_t;
+ struct gdCache_element_s {
+ gdCache_element_t *next;
+ void *userdata;
+ };
+
+ /* head structure */
+ typedef struct gdCache_head_s gdCache_head_t;
+ struct gdCache_head_s {
+ gdCache_element_t *mru;
+ int size;
+ char *error;
+ gdCacheTestFn_t gdCacheTest;
+ gdCacheFetchFn_t gdCacheFetch;
+ gdCacheReleaseFn_t gdCacheRelease;
+ };
+
+ /* function templates */
+ gdCache_head_t *gdCacheCreate(int size,
+ gdCacheTestFn_t gdCacheTest,
+ gdCacheFetchFn_t gdCacheFetch,
+ gdCacheReleaseFn_t gdCacheRelease
+ );
+
+ void gdCacheDelete(gdCache_head_t *head);
+
+ void *gdCacheGet(gdCache_head_t *head, void *keydata);
+
+#ifdef __cplusplus
+}
+#endif