First commit

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

1 files changed, 40 insertions, 0 deletions

diff --git a/libautomata_execute_kmp_automaton.c b/libautomata_execute_kmp_automaton.c
new file mode 100644
index 0000000..69ffcce
--- /dev/null
+++ b/libautomata_execute_kmp_automaton.c
@@ -0,0 +1,40 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+
+
+void *
+libautomata_execute_kmp_automaton(const void *haystack, size_t length, LIBAUTOMATA_KMP_AUTOMATON *automaton)
+{
+	const void *pattern = (void *)&automaton->next[automaton->length + 1U];
+	size_t i = 0;
+
+#define INTRINSIC(TYPE)\
+	(((const TYPE *)pattern)[automaton->position] == ((const TYPE *)haystack)[i])
+
+#define MEMCMP(WIDTH)\
+	(!memcmp(&((const char *)pattern)[automaton->position * automaton->elemsize],\
+	         &((const char *)haystack)[i * automaton->elemsize],\
+	         automaton->elemsize))
+
+#define IMPLEMENT(EQ, EQ_PARAM)\
+	while (i < length) {\
+		while (automaton->position != SIZE_MAX && !(EQ(EQ_PARAM)))\
+			automaton->position = automaton->next[automaton->position];\
+		i++;\
+		if (++automaton->position == automaton->length)\
+			goto found;\
+	}\
+	return NULL
+
+	switch (automaton->elemsize) {
+	case sizeof(uint8_t):  IMPLEMENT(INTRINSIC, uint8_t);
+	case sizeof(uint16_t): IMPLEMENT(INTRINSIC, uint16_t);
+	case sizeof(uint32_t): IMPLEMENT(INTRINSIC, uint32_t);
+	case sizeof(uint64_t): IMPLEMENT(INTRINSIC, uint64_t);
+	default:               IMPLEMENT(MEMCMP, elemsize);
+	}
+
+found:
+	automaton->position = automaton->next[automaton->position];
+	return &(*(char **)(void *)&haystack)[i];
+}