Added utility functions

src/utils.c

+#include <stdlib.h>
+
+#include "../include/gesa.h"
+
+
+int GESA_calculate_lcp(GESA_char_t const* const  string,
+                       size_t const              length,
+                       GESA_index_t const* const sa,
+                       GESA_index_t* const       lcp)
+{
+    GESA_index_t* const rank = malloc(length * sizeof(*rank));
+    if (rank == NULL)
+    {
+        return 1; // memory allocation failed
+    } // if
+
+    for (size_t i = 0; i < length; ++i)
+    {
+        rank[sa[i]] = i;
+    } // for
+
+    GESA_index_t h = 0;
+    for (size_t i = 0; i < length; ++i)
+    {
+        if (rank[i] > 0)
+        {
+            GESA_index_t const j = sa[rank[i] - 1];
+            while ((size_t) i + h < length &&
+                   (size_t) j + h < length &&
+                   string[i + h] == string[j + h])
+            {
+                h += 1;
+            } // while
+
+            lcp[rank[i]] = h;
+            if (h > 0)
+            {
+                h -= 1;
+            } // if
+        } // if
+    } // for
+    free(rank);
+
+    return 0;
+} // GESA_calculate_lcp
+
+
+int GESA_calculate_childtab(GESA const* const   gesa,
+                            GESA_index_t* const childtab)
+{
+    static size_t const STACK_SIZE = 2048;
+
+    GESA_index_t stack[STACK_SIZE];
+} // GESA_calculate_childtab