From 7e0f021a9aec35fd8e6725e87e3313b101d26f5e Mon Sep 17 00:00:00 2001
From: Tobias Klauser <tklauser@distanz.ch>
Date: Sun, 27 Jan 2008 11:37:44 +0100
Subject: Initial import (2.0.2-6)

---
 reference/C/CONTRIB/OR_PRACTICAL_C/17_1.c | 117 ++++++++++++++++++++++++++++++
 1 file changed, 117 insertions(+)
 create mode 100644 reference/C/CONTRIB/OR_PRACTICAL_C/17_1.c

(limited to 'reference/C/CONTRIB/OR_PRACTICAL_C/17_1.c')

diff --git a/reference/C/CONTRIB/OR_PRACTICAL_C/17_1.c b/reference/C/CONTRIB/OR_PRACTICAL_C/17_1.c
new file mode 100644
index 0000000..f0f68c9
--- /dev/null
+++ b/reference/C/CONTRIB/OR_PRACTICAL_C/17_1.c
@@ -0,0 +1,117 @@
+/********************************************************
+ * infinite-array -- routines to handle infinite arrays *
+ *                                                      *
+ * An infinite array is an array that grows as needed.  *
+ * There is no index too large for an infinite array    *
+ * (unless we run out of memory).                       *
+ ********************************************************/
+#include "ia.h"                 /* get common definitions */
+#include <stdio.h>
+#include <stdlib.h>     /* ANSI Standard only */
+
+/*
+ * the following three variables implement
+ * a very simple pointer cache
+ *
+ * They store information on the last infinite array used,
+ *       the last bucket we had and the last index used
+ *
+ * They are initialized to values we know will never
+ * be used by any real array.
+ */
+static struct infinite_array *cache_array_ptr = NULL;
+static struct infinite_array *cache_bucket_ptr = NULL;
+static int cache_index = -1;
+/********************************************************
+ * ia_store -- store an element into an infinite array. *
+ *                                                      *
+ * Parameters                                           *
+ *      array_ptr -- pointer to the array to use        *
+ *      index   -- index into the array                 *
+ *      store_data -- data to store                     *
+ ********************************************************/
+void  ia_store(struct infinite_array * array_ptr, 
+    int index, float store_data)
+{
+    /* pointer to the current bucket */
+    struct infinite_array *current_ptr;
+    int   current_index;        /* index into the current bucket */
+
+    /* get the location in an infinite array cell */
+    struct infinite_array *ia_locate(
+       struct infinite_array *, int, int *);
+
+    current_ptr = ia_locate(array_ptr, index, &current_index);
+    current_ptr->data[current_index] = store_data;
+}
+/********************************************************
+ * ia_get -- get an element from an infinite array.     *
+ *                                                      *
+ * Parameters                                           *
+ *      array_ptr -- pointer to the array to use        *
+ *      index   -- index into the array                 *
+ *                                                      *
+ * Returns                                              *
+ *      the value of the element                        *
+ ********************************************************/
+float ia_get(struct infinite_array *array_ptr, int index)
+{
+    /* pointer to the current bucket */
+    struct infinite_array *current_ptr;
+    int   current_index;        /* index into the current bucket */
+
+    /* get the location an infinite array cell */
+    struct infinite_array *ia_locate();
+
+    current_ptr = ia_locate(array_ptr, index, &current_index);
+    return (current_ptr->data[current_index]);
+}
+/********************************************************
+ * ia_locate -- get the location of an infinite array   *
+ *              element.                                *
+ *                                                      *
+ * Parameters                                           *
+ *      array_ptr -- pointer to the array to use        *
+ *      index   -- index into the array                 *
+ *      current_index -- pointer to the index into this *
+ *              bucket (returned)                       *
+ *                                                      *
+ * Returns                                              *
+ *      pointer to the current bucket                   *
+ ********************************************************/
+static struct infinite_array ia_locate(
+        struct infinite_array *array_ptr, int index
+        int *current_index_ptr)
+{
+    /* pointer to the current bucket */
+    struct infinite_array *current_ptr;
+
+    /* see if the cache will do us any good */
+    if ((cache_array_ptr == array_ptr) && (index >= cache_index)) {
+        current_ptr = cache_bucket_ptr;
+        *current_index_ptr = index - cache_index;
+    } else {
+        current_ptr = array_ptr;
+        *current_index_ptr = index;
+    }
+
+    while (*current_index_ptr > BLOCK_SIZE) {
+        if (current_ptr->next == NULL) {
+            current_ptr->next =
+                (struct infinite_array *)
+                malloc(sizeof(struct infinite_array));
+            if (current_ptr->next == NULL) {
+                (void) fprintf(stderr, "Error:Out of memory\n");
+                exit(8);
+            }
+        }
+        current_ptr = current_ptr->next;
+        *current_index_ptr -= BLOCK_SIZE;
+    }
+
+    cache_index = index - (index % BLOCK_SIZE);
+    cache_array_ptr = array_ptr;
+    cache_bucket_ptr = current_ptr;
+
+    return (current_ptr);
+}
-- 
cgit v1.2.3-54-g00ecf