diff options
Diffstat (limited to '')
| -rw-r--r-- | cpukit/score/include/rtems/score/bitfield.h | 69 |
1 files changed, 39 insertions, 30 deletions
diff --git a/cpukit/score/include/rtems/score/bitfield.h b/cpukit/score/include/rtems/score/bitfield.h index 5b4c678457..2f097a0c1a 100644 --- a/cpukit/score/include/rtems/score/bitfield.h +++ b/cpukit/score/include/rtems/score/bitfield.h @@ -1,8 +1,11 @@ -/* bitfield.h +/** + * @file bitfield.h * * This include file contains all bit field manipulation routines. - * - * COPYRIGHT (c) 1989-1999. + */ + +/* + * COPYRIGHT (c) 1989-2004. * On-Line Applications Research Corporation (OAR). * * The license and distribution terms for this file may be @@ -15,30 +18,26 @@ #ifndef __RTEMS_BITFIELD_h #define __RTEMS_BITFIELD_h +/** + * @defgroup ScoreBitfield Bitfield Handler + * + * This group contains functionality that is used to manipulate the + * priority bitfields used to lookup which priority has the highest + * priority ready to execute thread. + */ +/**@{*/ + #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 ) +/** + * This table is used by the generic bitfield routines to perform + * a highly optimized bit scan without the use of special CPU + * instructions. + */ #ifndef SCORE_INIT extern const unsigned char __log2table[256]; #else @@ -64,18 +63,27 @@ const unsigned char __log2table[256] = { #endif +/** + * This routine returns the @a _bit_number of the first bit set + * in the specified value. The correspondence between @a _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. + * + * @param _value (in) is the value to bit scan. + * @param _bit_number (in) is the position of the first bit set. + * + * @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. + * + * @note This routine must be a macro because if a CPU specific version + * is used it will most likely use inline assembly. + */ #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 uint32_t __value = (uint32_t ) (_value); \ @@ -86,12 +94,13 @@ const unsigned char __log2table[256] = { else \ (_bit_number) = __p[ __value >> 8 ]; \ } - #endif #ifdef __cplusplus } #endif +/**@}*/ + #endif /* end of include file */ |