diff options
Diffstat (limited to 'cpukit/score/include/rtems/score/threadimpl.h')
-rw-r--r-- | cpukit/score/include/rtems/score/threadimpl.h | 41 |
1 files changed, 41 insertions, 0 deletions
diff --git a/cpukit/score/include/rtems/score/threadimpl.h b/cpukit/score/include/rtems/score/threadimpl.h index bfaf1fdf67..353093ce3a 100644 --- a/cpukit/score/include/rtems/score/threadimpl.h +++ b/cpukit/score/include/rtems/score/threadimpl.h @@ -587,6 +587,47 @@ RTEMS_INLINE_ROUTINE bool _Thread_Is_allocated_fp ( } #endif +/* + * If the CPU has hardware floating point, then we must address saving + * and restoring it as part of the context switch. + * + * The second conditional compilation section selects the algorithm used + * to context switch between floating point tasks. The deferred algorithm + * can be significantly better in a system with few floating point tasks + * because it reduces the total number of save and restore FP context + * operations. However, this algorithm can not be used on all CPUs due + * to unpredictable use of FP registers by some compilers for integer + * operations. + */ + +RTEMS_INLINE_ROUTINE void _Thread_Save_fp( Thread_Control *executing ) +{ +#if ( CPU_HARDWARE_FP == TRUE ) || ( CPU_SOFTWARE_FP == TRUE ) +#if ( CPU_USE_DEFERRED_FP_SWITCH != TRUE ) + if ( executing->fp_context != NULL ) + _Context_Save_fp( &executing->fp_context ); +#endif +#endif +} + +RTEMS_INLINE_ROUTINE void _Thread_Restore_fp( Thread_Control *executing ) +{ +#if ( CPU_HARDWARE_FP == TRUE ) || ( CPU_SOFTWARE_FP == TRUE ) +#if ( CPU_USE_DEFERRED_FP_SWITCH == TRUE ) + if ( (executing->fp_context != NULL) && + !_Thread_Is_allocated_fp( executing ) ) { + if ( _Thread_Allocated_fp != NULL ) + _Context_Save_fp( &_Thread_Allocated_fp->fp_context ); + _Context_Restore_fp( &executing->fp_context ); + _Thread_Allocated_fp = executing; + } +#else + if ( executing->fp_context != NULL ) + _Context_Restore_fp( &executing->fp_context ); +#endif +#endif +} + /** * This routine is invoked when the currently loaded floating * point context is now longer associated with an active thread. |