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[/] [openrisc/] [trunk/] [rtos/] [rtems/] [c/] [src/] [exec/] [score/] [include/] [rtems/] [score/] [bitfield.h] - Rev 593
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/* bitfield.h * * This include file contains all bit field manipulation routines. * * COPYRIGHT (c) 1989-1999. * On-Line Applications Research Corporation (OAR). * * The license and distribution terms for this file may be * found in the file LICENSE in this distribution or at * http://www.OARcorp.com/rtems/license.html. * * $Id: bitfield.h,v 1.2 2001-09-27 11:59:32 chris Exp $ */ #ifndef __RTEMS_BITFIELD_h #define __RTEMS_BITFIELD_h #ifdef __cplusplus extern "C" { #endif /* * _Bitfield_Find_first_bit * * DESCRIPTION: * * This routine returns the bit_number of the first bit set * in the specified value. The correspondence between bit_number * and actual bit position is processor dependent. The search for * the first bit set may run from most to least significant bit * or vice-versa. * * NOTE: * * This routine is used when the executing thread is removed * from the ready state and, as a result, its performance has a * significant impact on the performance of the executive as a whole. */ #if ( CPU_USE_GENERIC_BITFIELD_DATA == TRUE ) #ifndef SCORE_INIT extern const unsigned char __log2table[256]; #else const unsigned char __log2table[256] = { 7, 7, 6, 6, 5, 5, 5, 5, 4, 4, 4, 4, 4, 4, 4, 4, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }; #endif #endif #if ( CPU_USE_GENERIC_BITFIELD_CODE == FALSE ) #define _Bitfield_Find_first_bit( _value, _bit_number ) \ _CPU_Bitfield_Find_first_bit( _value, _bit_number ) #else /* * The following must be a macro because if a CPU specific version * is used it will most likely use inline assembly. */ #define _Bitfield_Find_first_bit( _value, _bit_number ) \ { \ register unsigned32 __value = (unsigned32) (_value); \ register const unsigned char *__p = __log2table; \ \ if ( __value < 0x100 ) \ (_bit_number) = __p[ __value ] + 8; \ else \ (_bit_number) = __p[ __value >> 8 ]; \ } #endif #ifdef __cplusplus } #endif #endif /* end of include file */
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