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Diffstat (limited to 'cpukit/score/include/rtems/score/bitfield.h')
-rw-r--r-- | cpukit/score/include/rtems/score/bitfield.h | 98 |
1 files changed, 98 insertions, 0 deletions
diff --git a/cpukit/score/include/rtems/score/bitfield.h b/cpukit/score/include/rtems/score/bitfield.h new file mode 100644 index 0000000000..da84344af8 --- /dev/null +++ b/cpukit/score/include/rtems/score/bitfield.h @@ -0,0 +1,98 @@ +/* bitfield.h + * + * This include file contains all bit field manipulation routines. + * + * COPYRIGHT (c) 1989-1997. + * On-Line Applications Research Corporation (OAR). + * Copyright assigned to U.S. Government, 1994. + * + * The license and distribution terms for this file may in + * the file LICENSE in this distribution or at + * http://www.OARcorp.com/rtems/license.html. + * + * $Id$ + */ + +#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 */ |