added a C implementation of KMP search supporting NULL bytes

MANIFEST.in

@@ -2,4 +2,5 @@ include AUTHORS.rst
 include CONTRIBUTING.rst
 include HISTORY.rst
 include LICENSE
-include README.rst
+include README.rst
+include fuzzysearch/kmp.h

fuzzysearch/kmp.c

@@ -0,0 +1,53 @@
+#include <Python.h>
+#include "fuzzysearch/kmp.h"
+
+void preKMP(const char *subseq, int subseq_len, int *kmpNext) {
+    int i, j;
+
+    i = 0;
+    j = kmpNext[0] = -1;
+    while (i != subseq_len) {
+        while (j != -1 && subseq[i] != subseq[j])
+            j = kmpNext[j];
+        i++;
+        j++;
+        kmpNext[i] = (subseq[i] == subseq[j]) ? kmpNext[j] : j;
+    }
+}
+
+struct KMPstate KMP_init(const char *subseq, int subseq_len,
+                         const char *seq, int seq_len,
+                         int *kmpNext) {
+    struct KMPstate retval = {
+        .sequence_ptr = seq,
+        .sequence_end = seq + seq_len,
+        .subsequence = subseq,
+        .kmpNext = kmpNext,
+        .subseq_index = 0,
+        .subseq_len = subseq_len,
+    };
+    return retval;
+}
+
+const char* KMP_find_next(struct KMPstate *kmp_state) {
+    const char *sequence_ptr = kmp_state->sequence_ptr;
+    const char *sequence_end = kmp_state->sequence_end;
+    const char *subsequence = kmp_state->subsequence;
+    int *kmpNext = kmp_state->kmpNext;
+    int subseq_index = kmp_state->subseq_index;
+    int subseq_len = kmp_state->subseq_len;
+
+    while (sequence_ptr != sequence_end) {
+        while (subseq_index != -1 && subsequence[subseq_index] != (*sequence_ptr))
+            subseq_index = kmpNext[subseq_index];
+        subseq_index++;
+        sequence_ptr++;
+        if (subseq_index == subseq_len) {
+            kmp_state->subseq_index = kmpNext[subseq_index];
+            kmp_state->sequence_ptr = sequence_ptr;
+            return sequence_ptr - subseq_len;
+        }
+    }
+
+    return NULL;
+}

fuzzysearch/kmp.h

@@ -0,0 +1,16 @@
+struct KMPstate {
+    const char *sequence_ptr;
+    const char *sequence_end;
+    const char *subsequence;
+    int *kmpNext;
+    int subseq_index;
+    int subseq_len;
+};
+
+void preKMP(const char *subsequence, int subsequence_len, int *kmpNext);
+
+struct KMPstate KMP_init(const char *subseq, int subseq_len,
+                         const char *seq, int seq_len,
+                         int *kmpNext);
+
+const char* KMP_find_next(struct KMPstate *kmp_state);