Add memelem and memrelem

Signed-off-by: Mattias Andrée <maandree@kth.se>

1 files changed, 82 insertions, 0 deletions

diff --git a/memrelem.c b/memrelem.c
new file mode 100644
index 0000000..cc11d9e
--- /dev/null
+++ b/memrelem.c
@@ -0,0 +1,82 @@
+/* See LICENSE file for copyright and license details. */
+#include "libsimple.h"
+#ifndef TEST
+
+
+void *
+libsimple_memrelem(const void *hay_, size_t hayn, const void *sub_, size_t subn)
+{
+	if (!subn)
+		return (void *)hay_;
+
+	switch (subn) {
+	case 1:
+		{
+			uint8_t *hay = (void *)hay_;
+			uint8_t sub = *(uint8_t *)sub_;
+			for (hay += hayn; hayn--;)
+				if (*--hay == sub)
+					return hay;
+			break;
+		}
+	case 2:
+		{
+			uint16_t *hay = (void *)hay_;
+			uint16_t sub = *(uint16_t *)sub_;
+			for (hay += hayn; hayn--;)
+				if (*--hay == sub)
+					return hay;
+			break;
+		}
+	case 4:
+		{
+			uint32_t *hay = (void *)hay_;
+			uint32_t sub = *(uint32_t *)sub_;
+			for (hay += hayn; hayn--;)
+				if (*--hay == sub)
+					return hay;
+			break;
+		}
+	case 8:
+		{
+			uint64_t *hay = (void *)hay_;
+			uint64_t sub = *(uint64_t *)sub_;
+			for (hay += hayn; hayn--;)
+				if (*--hay == sub)
+					return hay;
+			break;
+		}
+	default:
+		{
+			char *hay = (void *)hay_;
+			const char *sub = sub_;
+			for (hay += hayn * subn; hayn--;) {
+				hay -= subn;
+				if (!memcmp(hay, sub, subn))
+					return hay;
+			}
+			break;
+
+		}
+	}
+
+	return NULL;
+}
+
+
+#else
+#include "test.h"
+
+int
+main(void)
+{
+	assert(!strcmpnul(libsimple_memrelem("12345634", 4, "", 0), "12345634"));
+	assert(!strcmpnul(libsimple_memrelem("12345634", 4, "34", 2), "34"));
+	assert(!libsimple_memrelem("12345634", 4, "xx", 2));
+	assert(!libsimple_memrelem("13456342", 4, "34", 2));
+	assert(!libsimple_memrelem("12345634", 0, "34", 2));
+	assert(!strcmpnul(libsimple_memrelem("12345634", 0, "34", 0), "12345634"));
+	return 0;
+}
+
+#endif