X-Git-Url: http://git.ozlabs.org/?a=blobdiff_plain;f=ccan%2Fjbitset%2F_info;fp=ccan%2Fjbitset%2F_info;h=4fa4dd981d49b53ba31bc046cbbef833ea0d02a6;hb=5e880e4ce45a3cececd0996b384482780a92070d;hp=0000000000000000000000000000000000000000;hpb=b734bbea227ae0c326a0f19f84b490d8895b2010;p=ccan

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+#include <stdio.h>
+#include <string.h>
+#include "config.h"
+
+/**
+ * jbitset - variable-length bitset (based on libJudy)
+ *
+ * This provides a convenient wrapper for using Judy bitsets; using
+ * integers or pointers as an index, Judy arrays provide an efficient
+ * bit array or bit map of variable size.
+ *
+ * jbitset.h simply contains wrappers for a size_t-indexed bitset, and
+ * jbitset_type.h contain a wrapper macro for pointer bitsets.
+ *
+ * Example:
+ * // Simple analysis of one-byte mallocs.
+ * #include <stdlib.h>
+ * #include <stdio.h>
+ * #include <err.h>
+ * #include <ccan/jbitset/jbitset_type.h>
+ * 
+ * // Define jbit_char_<op> and jbitset_char, for char * bitset.
+ * JBIT_DEFINE_TYPE(char, char);
+ * 
+ * int main(int argc, char *argv[])
+ * {
+ * 	unsigned int i, runs, reuse;
+ * 	size_t mindist = -1;
+ * 	struct jbitset_char *set = jbit_char_new();
+ * 	char *p, *prev;
+ * 
+ * 	runs = (argc == 1 ? 1000 : atoi(argv[1]));
+ * 	if (!runs)
+ * 		errx(1, "Invalid number of allocations '%s'", argv[1]);
+ * 
+ * 	for (i = 0; i < runs; i++)
+ * 		if (!jbit_char_set(set, malloc(1)))
+ * 			errx(1, "same pointer allocated twice!");
+ * 
+ * 	// Calculate minimum distance
+ * 	prev = jbit_char_first(set)+1;
+ * 	for (p = jbit_char_first(set); p; prev = p, p = jbit_char_next(set,p))
+ * 		if (p - prev < mindist)
+ * 			mindist = p - prev;
+ * 
+ * 	// Free them all, see how many we reallocate.
+ * 	for (p = jbit_char_first(set); p; p = jbit_char_next(set, p))
+ * 		free(p);
+ * 	for (reuse = 0, i = 0; i < runs; i++)
+ * 		reuse += jbit_char_test(set, malloc(1));
+ * 
+ * 	printf("Allocation density (bytes): %zu\n"
+ * 	       "Minimum inter-pointer distance: %zu\n"
+ * 	       "Reuse rate: %.0f%%\n",
+ * 	       (jbit_char_last(set) - jbit_char_first(set)) / runs,
+ * 	       mindist,
+ * 	       100.0 * reuse / runs);
+ * 	return 0;
+ * }
+ *
+ * License: LGPL (2 or any later version)
+ * Author: Rusty Russell <rusty@rustcorp.com.au>
+ */
+int main(int argc, char *argv[])
+{
+	if (argc != 2)
+		return 1;
+
+	if (strcmp(argv[1], "depends") == 0) {
+		printf("ccan/build_assert\n");
+		printf("ccan/compiler\n");
+		printf("Judy\n");
+		return 0;
+	}
+
+	if (strcmp(argv[1], "libs") == 0) {
+		printf("Judy\n");
+		return 0;
+	}
+
+	return 1;
+}