X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=tests%2Flibpspp%2Frange-set-test.c;h=8d6e68316834d707254b5888f92d1b41b1064bb6;hb=46e213d759e32e607cc2c04c6feb75809572d0cf;hp=9f444ad7e62eade3d692153f3fd62f8440a08c42;hpb=a091aa55567a4f2a9ecc08f126a959497be43f22;p=pspp

diff --git a/tests/libpspp/range-set-test.c b/tests/libpspp/range-set-test.c
index 9f444ad7e6..8d6e683168 100644
--- a/tests/libpspp/range-set-test.c
+++ b/tests/libpspp/range-set-test.c
@@ -119,6 +119,47 @@ next_region (unsigned int pattern, unsigned int offset,
   return false;
 }
 
+/* Searches the bits in PATTERN from left to right starting from
+   just beyond bit OFFSET for one or more 1-bits.  If any are
+   found, sets *START to the bit index of the first and *WIDTH to
+   the number of contiguous 1-bits and returns true.  Otherwise,
+   returns false.
+   This implementation is designed to be obviously correct, not
+   to be efficient. */
+static bool
+prev_region (unsigned int pattern, unsigned int offset,
+             unsigned long int *start, unsigned long int *width)
+{
+  unsigned int i;
+
+  assert (offset <= UINT_BIT);
+  for (i = offset; i-- > 0; )
+    if (pattern & (1u << i))
+      {
+        *start = i;
+        *width = 1;
+        while (i-- > 0 && pattern & (1u << i))
+          {
+            ++*width;
+            --*start;
+          }
+        return true;
+      }
+  return false;
+}
+
+/* Searches the bits in PATTERN from right to left starting from
+   bit OFFSET.  Returns the bit index of the first 1-bit found,
+   or ULONG_MAX if none is found. */
+static unsigned long int
+next_1bit (unsigned int pattern, unsigned int offset)
+{
+  for (; offset < UINT_BIT; offset++)
+    if (pattern & (1u << offset))
+      return offset;
+  return ULONG_MAX;
+}
+
 /* Prints the regions in RS to stdout. */
 static void UNUSED
 print_regions (const struct range_set *rs)
@@ -139,6 +180,7 @@ check_pattern (const struct range_set *rs, unsigned int pattern)
 {
   const struct range_set_node *node;
   unsigned long int start, width;
+  unsigned long int s1, s2;
   int i;
 
   for (node = rand () % 2 ? range_set_first (rs) : range_set_next (rs, NULL),
@@ -153,6 +195,52 @@ check_pattern (const struct range_set *rs, unsigned int pattern)
     }
   check (node == NULL);
 
+  for (node = rand () % 2 ? range_set_last (rs) : range_set_prev (rs, NULL),
+         start = UINT_BIT;
+       prev_region (pattern, start, &start, &width);
+       node = range_set_prev (rs, node))
+    {
+      check (node != NULL);
+      check (range_set_node_get_start (node) == start);
+      check (range_set_node_get_end (node) == start + width);
+      check (range_set_node_get_width (node) == width);
+    }
+  check (node == NULL);
+
+  /* Scan from all possible positions, resetting the cache each
+     time, to ensure that we get the correct answers without
+     caching. */
+  for (start = 0; start <= 32; start++)
+    {
+      struct range_set *nonconst_rs = CONST_CAST (struct range_set *, rs);
+      nonconst_rs->cache_end = 0;
+      s1 = range_set_scan (rs, start);
+      s2 = next_1bit (pattern, start);
+      check (s1 == s2);
+    }
+
+  /* Scan in forward order to exercise expected cache behavior. */
+  for (s1 = range_set_scan (rs, 0), s2 = next_1bit (pattern, 0); ;
+       s1 = range_set_scan (rs, s1 + 1), s2 = next_1bit (pattern, s2 + 1))
+    {
+      check (s1 == s2);
+      if (s1 == ULONG_MAX)
+        break;
+    }
+
+  /* Scan in random order to frustrate cache. */
+  for (i = 0; i < 32; i++)
+    {
+      start = rand () % 32;
+      s1 = range_set_scan (rs, start);
+      s2 = next_1bit (pattern, start);
+      check (s1 == s2);
+    }
+
+  /* Test range_set_scan() with negative cache. */
+  check (!range_set_contains (rs, 999));
+  check (range_set_scan (rs, 1111) == ULONG_MAX);
+
   for (i = 0; i < UINT_BIT; i++)
     check (range_set_contains (rs, i) == ((pattern & (1u << i)) != 0));
   check (!range_set_contains (rs,