diff options
author | Jeffrey O. Hill <hill@wombat.lanl.gov> | 2013-02-06 08:08:43 +0100 |
---|---|---|
committer | Sebastian Huber <sebastian.huber@embedded-brains.de> | 2013-03-11 17:57:41 +0100 |
commit | 1cddf47a4dedaefbd8895fb658ffc69a80631493 (patch) | |
tree | 0a6f99033d879b4023915ef74dba64d4b983594f /cpukit | |
parent | nios2: Rename file (diff) | |
download | rtems-1cddf47a4dedaefbd8895fb658ffc69a80631493.tar.bz2 |
nios2: Add _Nios2_Count_leading_zeros()
Add _Nios2_Count_trailing_zeros(). They are currently more efficient
than the corresponding GCC builtins.
Diffstat (limited to 'cpukit')
-rw-r--r-- | cpukit/score/cpu/nios2/Makefile.am | 1 | ||||
-rw-r--r-- | cpukit/score/cpu/nios2/preinstall.am | 4 | ||||
-rw-r--r-- | cpukit/score/cpu/nios2/rtems/score/nios2-count-zeros.h | 70 |
3 files changed, 75 insertions, 0 deletions
diff --git a/cpukit/score/cpu/nios2/Makefile.am b/cpukit/score/cpu/nios2/Makefile.am index 28587d814f..25ff46abfd 100644 --- a/cpukit/score/cpu/nios2/Makefile.am +++ b/cpukit/score/cpu/nios2/Makefile.am @@ -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 diff --git a/cpukit/score/cpu/nios2/preinstall.am b/cpukit/score/cpu/nios2/preinstall.am index d0d846d609..92e75e1a0e 100644 --- a/cpukit/score/cpu/nios2/preinstall.am +++ b/cpukit/score/cpu/nios2/preinstall.am @@ -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 diff --git a/cpukit/score/cpu/nios2/rtems/score/nios2-count-zeros.h b/cpukit/score/cpu/nios2/rtems/score/nios2-count-zeros.h new file mode 100644 index 0000000000..3e16a8aeef --- /dev/null +++ b/cpukit/score/cpu/nios2/rtems/score/nios2-count-zeros.h @@ -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 */ |