From 24bf11eca11947d961cc9bb5f7d92dabff169e93 Mon Sep 17 00:00:00 2001 From: Sebastian Huber Date: Wed, 12 Feb 2014 10:31:38 +0100 Subject: score: Add CPU counter support Add a CPU counter interface to allow access to a free-running counter. It is useful to measure short time intervals. This can be used for example to enable profiling of critical low-level functions. Add two busy wait functions rtems_counter_delay_ticks() and rtems_counter_delay_nanoseconds() implemented via the CPU counter. --- cpukit/score/cpu/no_cpu/rtems/score/cpu.h | 34 +++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+) (limited to 'cpukit/score/cpu/no_cpu/rtems/score') diff --git a/cpukit/score/cpu/no_cpu/rtems/score/cpu.h b/cpukit/score/cpu/no_cpu/rtems/score/cpu.h index 783da76dee..9fdc7fc5a2 100644 --- a/cpukit/score/cpu/no_cpu/rtems/score/cpu.h +++ b/cpukit/score/cpu/no_cpu/rtems/score/cpu.h @@ -1426,6 +1426,40 @@ static inline uint32_t CPU_swap_u32( #define CPU_swap_u16( value ) \ (((value&0xff) << 8) | ((value >> 8)&0xff)) +/** + * @brief Unsigned integer type for CPU counter values. + */ +typedef uint32_t CPU_Counter_ticks; + +/** + * @brief Returns the current CPU counter value. + * + * A CPU counter is some free-running counter. It ticks usually with a + * frequency close to the CPU or system bus clock. The board support package + * must ensure that this function works before the RTEMS initialization. + * Otherwise invalid profiling statistics will be gathered. + * + * @return The current CPU counter value. + */ +CPU_Counter_ticks _CPU_Counter_read( void ); + +/** + * @brief Returns the difference between the second and first CPU counter + * value. + * + * This operation may be carried out as a modulo operation depending on the + * range of the CPU counter device. + * + * @param[in] second The second CPU counter value. + * @param[in] first The first CPU counter value. + * + * @return Returns second minus first modulo counter period. + */ +CPU_Counter_ticks _CPU_Counter_difference( + CPU_Counter_ticks second, + CPU_Counter_ticks first +); + #ifdef RTEMS_SMP /** * @brief Returns the index of the current processor. -- cgit v1.2.3