add missing file (bug #2843)
authorRussell Bryant <russell@russellbryant.com>
Mon, 15 Nov 2004 04:32:12 +0000 (04:32 +0000)
committerRussell Bryant <russell@russellbryant.com>
Mon, 15 Nov 2004 04:32:12 +0000 (04:32 +0000)
git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@4254 65c4cc65-6c06-0410-ace0-fbb531ad65f3

codecs/log2comp.h [new file with mode: 0755]

diff --git a/codecs/log2comp.h b/codecs/log2comp.h
new file mode 100755 (executable)
index 0000000..9f39241
--- /dev/null
@@ -0,0 +1,63 @@
+/* log2comp.h - various base 2 log computation versions
+ * 
+ * Asterisk -- A telephony toolkit for Linux.
+ *
+ * Implementation by Alex Volkov <codepro@usa.net>
+ *
+ * Copyright (c) 2004, Digium
+ *
+ * This program is free software, distributed under the terms of
+ * the GNU General Public License
+ *
+ * Define WANT_ASM before including this file to use assembly
+ *   whenever possible
+ */
+
+#if defined(_MSC_VER)
+#      define inline __inline
+#elif defined(__GNUC__)
+#      define inline __inline__
+#else
+#      define inline
+#endif
+
+#if defined(WANT_ASM) && defined(_MSC_VER) && defined(_M_IX86)
+/* MS C Inline Asm */
+#      pragma warning( disable : 4035 )
+static inline int log2(int val) { __asm
+{
+       xor             eax, eax
+       dec             eax
+       bsr             eax, val
+}}
+#      pragma warning( default : 4035 )
+#elif defined(WANT_ASM) && defined(__GNUC__) && (defined(__i386__) || defined(i386))
+/* GNU Inline Asm */
+static inline int log2(int val)
+{
+       int a;
+       __asm__
+       ("\
+               xorl    %0, %0          ;\
+               decl    %0                      ;\
+               bsrl    %1, %0          ;\
+               "
+               : "=r" (a)
+               : "mr" (val)
+               : "cc"
+       );
+       return a;
+}
+#else
+/* no ASM for this compiler and/or platform */
+/* rather slow base 2 log computation
+ * Using looped shift.
+ */
+static inline int log2(int val)
+{
+       int i;
+       for (i = -1; val; ++i, val >>= 1)
+               ;
+       return (i);
+}
+#endif