Add symbol table support

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@1918 42af7a65-404d-4744-a932-0658087f49c3

1 files changed, 127 insertions, 0 deletions

diff --git a/nuttx/binfmt/symtab_findorderedbyvalue.c b/nuttx/binfmt/symtab_findorderedbyvalue.c
new file mode 100644
index 000000000..c1f824769
--- /dev/null
+++ b/nuttx/binfmt/symtab_findorderedbyvalue.c
@@ -0,0 +1,127 @@
+/****************************************************************************
+ * binfmt/symtab_findorderedbyvalue.c
+ *
+ *   Copyright (C) 2009 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#include <sys/types.h>
+
+#include <debug.h>
+#include <assert.h>
+#include <errno.h>
+
+#include <nuttx/symtab.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/***********************************************************************
+ * Public Functions
+ ***********************************************************************/
+
+/****************************************************************************
+ * Name: symtab_findorderedbyvalue
+ *
+ * Description:
+ *   Find the symbol in the symbol table whose value closest (but not greater
+ *   than), the provided value. This version assumes that table is ordered
+ *   with respect to symbol name.
+ *
+ * Returned Value:
+ *   A reference to the symbol table entry if an entry with the matching
+ *   name is found; NULL is returned if the entry is not found.
+ *
+ ****************************************************************************/
+
+FAR const struct symtab_s *
+symtab_findorderedbyvalue(FAR const struct symtab_s *symtab,
+                          FAR void *value, int nsyms)
+{
+  int low  = 0;
+  int high = nsyms -1;
+  int mid;
+
+  /* Loop until the range has been isolated to a single symbol table
+   * entry that may or may not match the search name.
+   */
+
+  DEBUGASSERT(symtab != NULL);
+  while (low < high)
+    {
+      /* Compare the name to the one in the middle.  (or just below
+       * the middle in the case where one is even and one is odd).
+       */
+
+      mid = (low + high) >> 1;
+      if ( value < symtab[mid].sym_value)
+        {
+          high = mid - 1;
+        }
+      else if (value > symtab[mid].sym_value)
+        {
+          low = mid + 1;
+        }
+      else /* if (value == symtab[mid].sym_value) */
+        {
+          return &symtab[mid];
+        }
+    }
+
+ /* low == high... One final check.  We might not have actually tested
+  * the final symtab[] name.
+  *
+  *   Example: Only the last pass through loop, suppose low = 1, high = 2,
+  *   mid = 1, and symtab[high].sym_name == name.  Then we would get here with
+  *   low = 2, high = 2, but symtab[2].sym_name was never tested.
+  */
+
+  return value == symtab[low].sym_value ? &symtab[low] : NULL;
+}
+