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/**
* @file rtems/score/cpu.h
*/
/*
* $Id$
*/
#ifndef _RTEMS_SCORE_CPU_H
#define _RTEMS_SCORE_CPU_H
#include <rtems/score/powerpc.h> /* pick up machine definitions */
#ifndef ASM
#include <rtems/score/types.h>
#endif
/* conditional compilation parameters */
/*
* Should the calls to _Thread_Enable_dispatch be inlined?
*
* If TRUE, then they are inlined.
* If FALSE, then a subroutine call is made.
*
* Basically this is an example of the classic trade-off of size
* versus speed. Inlining the call (TRUE) typically increases the
* size of RTEMS while speeding up the enabling of dispatching.
* [NOTE: In general, the _Thread_Dispatch_disable_level will
* only be 0 or 1 unless you are in an interrupt handler and that
* interrupt handler invokes the executive.] When not inlined
* something calls _Thread_Enable_dispatch which in turns calls
* _Thread_Dispatch. If the enable dispatch is inlined, then
* one subroutine call is avoided entirely.]
*/
#define CPU_INLINE_ENABLE_DISPATCH FALSE
/*
* Should the body of the search loops in _Thread_queue_Enqueue_priority
* be unrolled one time? In unrolled each iteration of the loop examines
* two "nodes" on the chain being searched. Otherwise, only one node
* is examined per iteration.
*
* If TRUE, then the loops are unrolled.
* If FALSE, then the loops are not unrolled.
*
* The primary factor in making this decision is the cost of disabling
* and enabling interrupts (_ISR_Flash) versus the cost of rest of the
* body of the loop. On some CPUs, the flash is more expensive than
* one iteration of the loop body. In this case, it might be desirable
* to unroll the loop. It is important to note that on some CPUs, this
* code is the longest interrupt disable period in RTEMS. So it is
* necessary to strike a balance when setting this parameter.
*/
#define CPU_UNROLL_ENQUEUE_PRIORITY FALSE
#ifdef _OLD_EXCEPTIONS
#include <rtems/old-exceptions/cpu.h>
#else
#include <rtems/new-exceptions/cpu.h>
#endif
#ifndef ASM
/* The following routine swaps the endian format of an unsigned int.
* It must be static because it is referenced indirectly.
*
* This version will work on any processor, but if there is a better
* way for your CPU PLEASE use it. The most common way to do this is to:
*
* swap least significant two bytes with 16-bit rotate
* swap upper and lower 16-bits
* swap most significant two bytes with 16-bit rotate
*
* Some CPUs have special instructions which swap a 32-bit quantity in
* a single instruction (e.g. i486). It is probably best to avoid
* an "endian swapping control bit" in the CPU. One good reason is
* that interrupts would probably have to be disabled to insure that
* an interrupt does not try to access the same "chunk" with the wrong
* endian. Another good reason is that on some CPUs, the endian bit
* endianness for ALL fetches -- both code and data -- so the code
* will be fetched incorrectly.
*/
static inline uint32_t CPU_swap_u32(
uint32_t value
)
{
uint32_t swapped;
asm volatile("rlwimi %0,%1,8,24,31;"
"rlwimi %0,%1,24,16,23;"
"rlwimi %0,%1,8,8,15;"
"rlwimi %0,%1,24,0,7;" :
"=&r" ((swapped)) : "r" ((value)));
return( swapped );
}
#define CPU_swap_u16( value ) \
(((value&0xff) << 8) | ((value >> 8)&0xff))
#endif /* ASM */
#endif /* _RTEMS_SCORE_CPU_H */
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