Changeset 5407cdc for libcfa/src/math.hfa

Timestamp:

Apr 28, 2021, 4:56:50 PM (5 years ago)

Author:

Thierry Delisle <tdelisle@…>

Branches:

ADT, arm-eh, ast-experimental, enum, forall-pointer-decay, jacob/cs343-translation, master, new-ast-unique-expr, pthread-emulation, qualifiedEnum

Children:

8d66610

Parents:

feacef9 (diff), b7fd2db6 (diff)
Note: this is a merge changeset, the changes displayed below correspond to the merge itself.
Use the (diff) links above to see all the changes relative to each parent.

Message:

Merge branch 'master' of plg.uwaterloo.ca:software/cfa/cfa-cc

File:

• libcfa/src/math.hfa (modified) (2 diffs)

libcfa/src/math.hfa

@@ -5 +5 @@
 // file "LICENCE" distributed with Cforall.
 //
-// math --
+// math.hfa --
 //
 // Author           : Peter A. Buhr
 // Created On       : Mon Apr 18 23:37:04 2016
 // Last Modified By : Peter A. Buhr
-// Last Modified On : Mon Aug 24 08:56:20 2020
-// Update Count     : 126
+// Last Modified On : Thu Apr 15 11:47:56 2021
+// Update Count     : 132
 //
 
@@ -100 +100 @@
         long double _Complex log( long double _Complex x ) { return clogl( x ); }
 
+        // O(1) polymorphic integer log2, using clz, which returns the number of leading 0-bits, starting at the most
+        // significant bit (single instruction on x86)
+        int log2( unsigned int n ) { return n == 0 ? -1 : sizeof(n) * __CHAR_BIT__ - 1 - __builtin_clz( n ); }
+        long int log2( unsigned long int n ) { return n == 0 ? -1 : sizeof(n) * __CHAR_BIT__ - 1 - __builtin_clzl( n ); }
+        long long int log2( unsigned long long int n ) { return n == 0 ? -1 : sizeof(n) * __CHAR_BIT__ - 1 - __builtin_clzll( n ); }
         float log2( float x ) { return log2f( x ); }
         // extern "C" { double log2( double ); }