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author | Sebastian Huber <sebastian.huber@embedded-brains.de> | 2014-02-12 10:31:38 +0100 |
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committer | Sebastian Huber <sebastian.huber@embedded-brains.de> | 2014-02-14 10:28:29 +0100 |
commit | 24bf11eca11947d961cc9bb5f7d92dabff169e93 (patch) | |
tree | b28f3aa8a21df91e8feaf324613aa76460559837 /cpukit/score/cpu/no_cpu/rtems/score | |
parent | bsps/arm: Fix Cortex-A9 MPCore nanoseconds handler (diff) | |
download | rtems-24bf11eca11947d961cc9bb5f7d92dabff169e93.tar.bz2 |
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.
Diffstat (limited to 'cpukit/score/cpu/no_cpu/rtems/score')
-rw-r--r-- | cpukit/score/cpu/no_cpu/rtems/score/cpu.h | 34 |
1 files changed, 34 insertions, 0 deletions
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. |