/* This program is free software; you can redistribute it and/or modify it
* under the terms of the license (GNU LGPL) which comes with this package. */
+#define DJB2_HASH_FUNCTION
+//#define FNV_HASH_FUNCTION
+
#include "portable.h"
#include "xbt/misc.h"
#include "xbt/sysdep.h"
/*
* Diff related functions
*
- * Implementation of the algorithm described in "An O(NP) Sequence
- * Comparison Algorithm", by Sun Wu, Udi Manber, Gene Myers, and Webb
- * Miller.
+ * Implementation of the algorithm described in "An O(NP) Sequence Comparison
+ * Algorithm", by Sun Wu, Udi Manber, Gene Myers, and Webb Miller (Information
+ * Processing Letters 35(6):317-323, 1990), with the linear-space
+ * divide-and-conquer strategy described in "An O(ND) Difference Algorithm and
+ * Its Variations", by Eugene W. Myers (Algorithmica 1:251-266, 1986).
*/
struct subsequence {
}
/* Finds a longest common subsequence.
+ * Returns its length.
*/
-static void diff_compute_lcs(const char *vec_a[], int a0, int len_a,
- const char *vec_b[], int b0, int len_b,
- xbt_dynar_t common_sequence,
- struct subsequence *seqs, int *fp)
+static int diff_compute_lcs(const char *vec_a[], int a0, int len_a,
+ const char *vec_b[], int b0, int len_b,
+ xbt_dynar_t common_sequence,
+ struct subsequence *seqs, int *fp)
{
if (len_a > 0 && len_b > 0) {
struct subsequence subseq;
int ses_len = diff_middle_subsequence(vec_a, a0, len_a, vec_b, b0, len_b,
&subseq, seqs, fp);
- if (ses_len > 1) {
- int u = subseq.x + subseq.len;
- int v = subseq.y + subseq.len;
- diff_compute_lcs(vec_a, a0, subseq.x - a0, vec_b, b0, subseq.y - b0,
- common_sequence, seqs, fp);
+ int lcs_len = (len_a + len_b - ses_len) / 2;
+ if (lcs_len == 0) {
+ return 0;
+ } else if (ses_len > 1) {
+ int lcs_len1 = subseq.len;
+ if (lcs_len1 < lcs_len)
+ lcs_len1 += diff_compute_lcs(vec_a, a0, subseq.x - a0,
+ vec_b, b0, subseq.y - b0,
+ common_sequence, seqs, fp);
if (subseq.len > 0)
xbt_dynar_push(common_sequence, &subseq);
- diff_compute_lcs(vec_a, u, a0 + len_a - u, vec_b, v, b0 + len_b - v,
- common_sequence, seqs, fp);
+ if (lcs_len1 < lcs_len) {
+ int u = subseq.x + subseq.len;
+ int v = subseq.y + subseq.len;
+ diff_compute_lcs(vec_a, u, a0 + len_a - u, vec_b, v, b0 + len_b - v,
+ common_sequence, seqs, fp);
+ }
} else {
int len = MIN(len_a, len_b) - subseq.len;
if (subseq.x == a0 && subseq.y == b0) {
xbt_dynar_push(common_sequence, &subseq);
}
}
+ return lcs_len;
+ } else {
+ return 0;
}
}
return res;
}
+/**
+ * @brief Returns the hash code of a string.
+ */
+XBT_INLINE unsigned int xbt_dict_hash_ext(const char *str,
+ int str_len)
+{
+
+#ifdef DJB2_HASH_FUNCTION
+ /* fast implementation of djb2 algorithm */
+ int c;
+ register unsigned int hash = 5381;
+
+ while (str_len--) {
+ c = *str++;
+ hash = ((hash << 5) + hash) + c; /* hash * 33 + c */
+ }
+# elif defined(FNV_HASH_FUNCTION)
+ register unsigned int hash = 0x811c9dc5;
+ unsigned char *bp = (unsigned char *) str; /* start of buffer */
+ unsigned char *be = bp + str_len; /* beyond end of buffer */
+
+ while (bp < be) {
+ /* multiply by the 32 bit FNV magic prime mod 2^32 */
+ hash +=
+ (hash << 1) + (hash << 4) + (hash << 7) + (hash << 8) +
+ (hash << 24);
+
+ /* xor the bottom with the current octet */
+ hash ^= (unsigned int) *bp++;
+ }
+
+# else
+ register unsigned int hash = 0;
+
+ while (str_len--) {
+ hash += (*str) * (*str);
+ str++;
+ }
+#endif
+
+ return hash;
+}
+
+/**
+ * @brief Returns the hash code of a string.
+ */
+XBT_INLINE unsigned int xbt_dict_hash(const char *str)
+{
+#ifdef DJB2_HASH_FUNCTION
+ /* fast implementation of djb2 algorithm */
+ int c;
+ register unsigned int hash = 5381;
+
+ while ((c = *str++)) {
+ hash = ((hash << 5) + hash) + c; /* hash * 33 + c */
+ }
+
+# elif defined(FNV_HASH_FUNCTION)
+ register unsigned int hash = 0x811c9dc5;
+
+ while (*str) {
+ /* multiply by the 32 bit FNV magic prime mod 2^32 */
+ hash +=
+ (hash << 1) + (hash << 4) + (hash << 7) + (hash << 8) +
+ (hash << 24);
+
+ /* xor the bottom with the current byte */
+ hash ^= (unsigned int) *str++;
+ }
+
+# else
+ register unsigned int hash = 0;
+
+ while (*str) {
+ hash += (*str) * (*str);
+ str++;
+ }
+#endif
+ return hash;
+}
+
#ifdef SIMGRID_TEST
#include "xbt/str.h"
