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nios2: Add _Nios2_Count_leading_zeros()

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Add _Nios2_Count_trailing_zeros().  They are currently more efficient
than the corresponding GCC builtins.
This commit is contained in:
Jeffrey O. Hill
2013-03-11 17:57:41 +01:00
committed by Sebastian Huber
parent 3ac61e5262
commit 1cddf47a4d
3 changed files with 75 additions and 0 deletions
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cpukit/score/cpu/nios2/Makefile.am
+1
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@@ -13,6 +13,7 @@ include_rtems_score_HEADERS =
include_rtems_score_HEADERS += rtems/score/cpu.h
include_rtems_score_HEADERS += rtems/score/nios2.h
include_rtems_score_HEADERS += rtems/score/nios2-utility.h
include_rtems_score_HEADERS += rtems/score/nios2-count-zeros.h
include_rtems_score_HEADERS += rtems/score/cpu_asm.h
include_rtems_score_HEADERS += rtems/score/types.h
cpukit/score/cpu/nios2/preinstall.am
+4
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@@ -39,6 +39,10 @@ $(PROJECT_INCLUDE)/rtems/score/nios2-utility.h: rtems/score/nios2-utility.h $(PR
$(INSTALL_DATA) $< $(PROJECT_INCLUDE)/rtems/score/nios2-utility.h
PREINSTALL_FILES += $(PROJECT_INCLUDE)/rtems/score/nios2-utility.h
$(PROJECT_INCLUDE)/rtems/score/nios2-count-zeros.h: rtems/score/nios2-count-zeros.h $(PROJECT_INCLUDE)/rtems/score/$(dirstamp)
$(INSTALL_DATA) $< $(PROJECT_INCLUDE)/rtems/score/nios2-count-zeros.h
PREINSTALL_FILES += $(PROJECT_INCLUDE)/rtems/score/nios2-count-zeros.h
$(PROJECT_INCLUDE)/rtems/score/cpu_asm.h: rtems/score/cpu_asm.h $(PROJECT_INCLUDE)/rtems/score/$(dirstamp)
$(INSTALL_DATA) $< $(PROJECT_INCLUDE)/rtems/score/cpu_asm.h
PREINSTALL_FILES += $(PROJECT_INCLUDE)/rtems/score/cpu_asm.h
cpukit/score/cpu/nios2/rtems/score/nios2-count-zeros.h
+70
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@@ -0,0 +1,70 @@
/*
* Author: Jeffrey O. Hill
*
* Copyright 2012. Los Alamos National Security, LLC.
* This material was produced under U.S. Government contract
* DE-AC52-06NA25396 for Los Alamos National Laboratory (LANL),
* which is operated by Los Alamos National Security, LLC for
* the U.S. Department of Energy. The U.S. Government has rights
* to use, reproduce, and distribute this software. NEITHER THE
* GOVERNMENT NOR LOS ALAMOS NATIONAL SECURITY, LLC MAKES ANY
* WARRANTY, EXPRESS OR IMPLIED, OR ASSUMES ANY LIABILITY FOR
* THE USE OF THIS SOFTWARE.
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.rtems.com/license/LICENSE.
*/
#ifndef _NIOS2_COUNT_ZEROS_H
#define _NIOS2_COUNT_ZEROS_H
#include <stdint.h>
#include <rtems/score/bitfield.h>
#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */
/*
* This implementation is currently much more efficient than
* the GCC provided __builtin_clz
*/
static inline unsigned _Nios2_Count_leading_zeros( uint32_t p )
{
unsigned bitIdx;
if ( p <= 0xffffu ) {
if ( p < 0x100u ) {
bitIdx = __log2table[ p ] + 24u;
} else {
bitIdx = __log2table[ p >> 8u ] + 16u;
}
} else {
p >>= 16u;
if ( p < 0x100u ) {
bitIdx = __log2table[ p ] + 8u;
} else {
bitIdx = __log2table[ p >> 8u ];
}
}
return bitIdx;
}
/*
* This implementation is currently much more efficient than
* the GCC provided __builtin_ctz
*/
static inline unsigned _Nios2_Count_trailing_zeros( uint32_t p )
{
return 31u - _Nios2_Count_leading_zeros( p & ( -p ) );
}
#ifdef __cplusplus
}
#endif /* __cplusplus */
#endif /* _NIOS2_COUNT_ZEROS_H */