Changeset 635 for trunk/kernel/libk/bits.h

Timestamp:

Jun 26, 2019, 11:42:37 AM (5 years ago)

Author:

alain

Message:

This version is a major evolution: The physical memory allocators,
defined in the kmem.c, ppm.c, and kcm.c files have been modified
to support remote accesses. The RPCs that were previously user
to allocate physical memory in a remote cluster have been removed.
This has been done to cure a dead-lock in case of concurrent page-faults.

This version 2.2 has been tested on a (4 clusters / 2 cores per cluster)
TSAR architecture, for both the "sort" and the "fft" applications.

File:

• trunk/kernel/libk/bits.h (modified) (3 diffs)

trunk/kernel/libk/bits.h

@@ -3 +3 @@
  *
  * Author   Ghassan Almaless (2008,2009,2010,2011,2012)
- *          Alain Greiner    (2016)
+ *          Alain Greiner    (2016,2017,2018,2019)
  *
  * Copyright (c) UPMC Sorbonne Universites
@@ -189 +189 @@
 
 /*********************************************************************************************
- * This function returns the number of bits to code a non-zero unsigned integer value.
- *********************************************************************************************
- * @ val   : value to analyse
- * @ returns number of bits
- ********************************************************************************************/
-static inline uint32_t bits_nr( uint32_t val )
-{
-        register uint32_t i;
-
-        for( i=0 ; val > 0 ; i++ ) 
-                val = val >> 1;
-
-        return i;
-}
-
-/*********************************************************************************************
- * This function takes an unsigned integer value as input argument, and returns another
- * unsigned integer, that is the (base 2) logarithm of the smallest power of 2 contained 
- * in the input value.
+ * This function takes a positive integer <val> as input argument, and returns the smallest
+ * integer <order> such as : 1<<order >= val. 
+ * In other words, <order> is the min number of bits to encode <val> values.
  *********************************************************************************************
  * @ val   : value to analyse
@@ -214 +198 @@
 static inline uint32_t bits_log2( uint32_t val )
 {
-        return (val == 0) ? 1 : bits_nr( val ) - 1;
+    uint32_t i;
+
+    if( val > 0 )
+    {
+        val--;
+        for( i=0 ; val > 0 ; i++ ) val = val >> 1;
+        return i;
+    }
+    return 0;
 }