1 files changed, 57 insertions, 0 deletions
diff --git a/memrmem.c b/memrmem.c
new file mode 100644
index 0000000..713ba34
--- /dev/null
+++ b/memrmem.c
@@ -0,0 +1,57 @@
+/* See LICENSE file for copyright and license details. */
+#include "libsimple.h"
+
+
+void *
+libsimple_memrmem(const void *hay_, size_t hayn, const void *sub_, size_t subn)
+{
+	char *hay = (void *)hay_, *start;
+	const char *sub = sub_;
+
+	if (!subn)
+		return hay;
+	if (hayn < subn)
+		return NULL;
+	if (subn == 1)
+		return libsimple_memrchr(hay, *sub, hayn);
+
+	start = hay;
+	hay = &hay[hayn - subn];
+	do {
+		if (*hay == *sub && !memcmp(hay, sub, subn))
+			return hay;
+	} while (hay-- != start);
+
+	return NULL;
+}
+
+
+#ifdef TEST
+#include <assert.h>
+
+int
+main(void)
+{
+	assert(!strcmp(libsimple_memrmem("test", 4, "test", 4), "test"));
+	assert(!strcmp(libsimple_memrmem("", 0, "", 0), ""));
+	assert(!strcmp(libsimple_memrmem("test", 4, "", 0), ""));
+	assert(!libsimple_memrmem("", 0, "test", 4));
+	assert(!libsimple_memrmem("t", 1, "test", 4));
+	assert(!strcmp(libsimple_memrmem("test", 4, "t", 1), "t"));
+	assert(!strcmp(libsimple_memrmem("test", 4, "e", 1), "est"));
+	assert(!strcmp(libsimple_memrmem("test", 4, "s", 1), "st"));
+	assert(!libsimple_memrmem("test", 4, "x", 1));
+	assert(!strcmp(libsimple_memrmem("test", 4, "te", 2), "test"));
+	assert(!strcmp(libsimple_memrmem("test", 4, "es", 2), "est"));
+	assert(!strcmp(libsimple_memrmem("test", 4, "st", 2), "st"));
+	assert(!strcmp(libsimple_memrmem("test", 5, "t", 2), "t"));
+	assert(!libsimple_memrmem("test", 4, "xx", 2));
+	assert(!strcmp(libsimple_memrmem("abc", 3, "c", 1), "c"));
+	assert(!strcmp(libsimple_memrmem("abc", 3, "bc", 2), "bc"));
+	assert(!strcmp(libsimple_memrmem("abc", 3, "abc", 3), "abc"));
+	assert(!libsimple_memrmem("abc", 3, "abc", 4));
+	assert(!strcmp(libsimple_memrmem("abcabc", 6, "bc", 2), "bc"));
+	return 0;
+}
+
+#endif