Bitfield Handler

Defines
#define	_Bitfield_Find_first_bit(_value, _bit_number)   _CPU_Bitfield_Find_first_bit( _value, _bit_number )
Variables
const unsigned char	__log2table [256]

---

Detailed Description

This handler encapsulates functionality that is used to manipulate the priority bitfields used to lookup which priority has the highest priority ready to execute thread.

---

Define Documentation

#define _Bitfield_Find_first_bit	(	_value,
		_bit_number		)	_CPU_Bitfield_Find_first_bit( _value, _bit_number )

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.

Parameters:

[in]	_value	is the value to bit scan.
[in]	_bit_number	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.

This routine must be a macro because if a CPU specific version is used it will most likely use inline assembly.

Referenced by _Priority_Get_highest().

---

Variable Documentation

const unsigned char __log2table[256]

This table is used by the generic bitfield routines to perform a highly optimized bit scan without the use of special CPU instructions.