* leb128.h: New file.

From-SVN: r187780

include/ChangeLog

@@ -1,3 +1,7 @@
+2012-05-22  Doug Evans  <dje@google.com>
+
+	* leb128.h: New file.
+
 2012-05-19  Gary Funck  <gary@intrepid.com>
 
 	* dwarf2.def: Update comment re: UPC extensions to reference

include/leb128.h

@@ -0,0 +1,124 @@
+/* Utilities for reading leb128 values.
+   Copyright (C) 2012 Free Software Foundation, Inc.
+
+This file is part of the libiberty library.
+Libiberty is free software; you can redistribute it and/or
+modify it under the terms of the GNU Library General Public
+License as published by the Free Software Foundation; either
+version 2 of the License, or (at your option) any later version.
+
+Libiberty is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with libiberty; see the file COPYING.LIB.  If not, write
+to the Free Software Foundation, Inc., 51 Franklin Street - Fifth Floor,
+Boston, MA 02110-1301, USA.  */
+
+/* The functions defined here can be speed critical.
+   Since they are all pretty small we keep things simple and just define
+   them all as "static inline".  */
+
+#ifndef LEB128_H
+#define LEB128_H
+
+/* Get a definition for inline.  */
+#include "ansidecl.h"
+
+/* Get a definition for NULL, size_t.  */
+#include <stddef.h>
+
+/* Decode the unsigned LEB128 constant at BUF into the variable pointed to
+   by R, and return the number of bytes read.
+   If we read off the end of the buffer, zero is returned,
+   and nothing is stored in R.
+
+   Note: The result is an int instead of a pointer to the next byte to be
+   read to avoid const-vs-non-const problems.  */
+
+static inline size_t
+read_uleb128_to_ull (const unsigned char *buf, const unsigned char *buf_end,
+		     unsigned long long *r)
+{
+  const unsigned char *p = buf;
+  unsigned int shift = 0;
+  unsigned long long result = 0;
+  unsigned char byte;
+
+  while (1)
+    {
+      if (p >= buf_end)
+	return 0;
+
+      byte = *p++;
+      result |= ((unsigned long long) (byte & 0x7f)) << shift;
+      if ((byte & 0x80) == 0)
+	break;
+      shift += 7;
+    }
+
+  *r = result;
+  return p - buf;
+}
+
+/* Decode the signed LEB128 constant at BUF into the variable pointed to
+   by R, and return the number of bytes read.
+   If we read off the end of the buffer, zero is returned,
+   and nothing is stored in R.
+
+   Note: The result is an int instead of a pointer to the next byte to be
+   read to avoid const-vs-non-const problems.  */
+
+static inline size_t
+read_sleb128_to_ll (const unsigned char *buf, const unsigned char *buf_end,
+		    long long *r)
+{
+  const unsigned char *p = buf;
+  unsigned int shift = 0;
+  long long result = 0;
+  unsigned char byte;
+
+  while (1)
+    {
+      if (p >= buf_end)
+	return 0;
+
+      byte = *p++;
+      result |= ((unsigned long long) (byte & 0x7f)) << shift;
+      shift += 7;
+      if ((byte & 0x80) == 0)
+	break;
+    }
+  if (shift < (sizeof (*r) * 8) && (byte & 0x40) != 0)
+    result |= -(((unsigned long long) 1) << shift);
+
+  *r = result;
+  return p - buf;
+}
+
+/* Return the number of bytes to read to skip past an LEB128 number in BUF.
+   If the end isn't found before reaching BUF_END, return zero.
+
+   Note: The result is an int instead of a pointer to the next byte to be
+   read to avoid const-vs-non-const problems.  */
+
+static inline size_t
+skip_leb128 (const unsigned char *buf, const unsigned char *buf_end)
+{
+  const unsigned char *p = buf;
+  unsigned char byte;
+
+  while (1)
+    {
+      if (p == buf_end)
+	return 0;
+
+      byte = *p++;
+      if ((byte & 0x80) == 0)
+	return p - buf;
+    }
+}
+
+#endif /* LEB128_H */