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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/sapi/src/cpucounterconverter.c | |
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/sapi/src/cpucounterconverter.c')
-rw-r--r-- | cpukit/sapi/src/cpucounterconverter.c | 39 |
1 files changed, 39 insertions, 0 deletions
diff --git a/cpukit/sapi/src/cpucounterconverter.c b/cpukit/sapi/src/cpucounterconverter.c new file mode 100644 index 0000000000..5b03d3c7a1 --- /dev/null +++ b/cpukit/sapi/src/cpucounterconverter.c @@ -0,0 +1,39 @@ +/* + * Copyright (c) 2014 embedded brains GmbH. All rights reserved. + * + * embedded brains GmbH + * Dornierstr. 4 + * 82178 Puchheim + * Germany + * <rtems@embedded-brains.de> + * + * The license and distribution terms for this file may be + * found in the file LICENSE in this distribution or at + * http://www.rtems.com/license/LICENSE. + */ + +#include <rtems/counter.h> + +RTEMS_STATIC_ASSERT(sizeof(rtems_counter_ticks) <= sizeof(uint32_t), type); + +static uint64_t to_ns_scaler = UINT64_C(1) << 32; + +static uint64_t from_ns_scaler = UINT64_C(1) << 32; + +uint64_t rtems_counter_ticks_to_nanoseconds( rtems_counter_ticks counter ) +{ + return (uint32_t) ((counter * to_ns_scaler) >> 32); +} + +rtems_counter_ticks rtems_counter_nanoseconds_to_ticks( uint32_t nanoseconds ) +{ + return (rtems_counter_ticks) ((nanoseconds * from_ns_scaler) >> 32); +} + +void rtems_counter_initialize_converter( uint32_t frequency ) +{ + uint64_t ns_per_s = UINT64_C(1000000000); + + to_ns_scaler = ((ns_per_s << 32) + frequency - 1) / frequency; + from_ns_scaler = ((UINT64_C(1) << 32) * frequency + ns_per_s - 1) / ns_per_s; +} |