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/sapi/src/cpucounterconverter.c | 39 +++++++++++++++++++++++++++++++++++ 1 file changed, 39 insertions(+) create mode 100644 cpukit/sapi/src/cpucounterconverter.c (limited to 'cpukit/sapi/src/cpucounterconverter.c') 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 + * + * + * 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_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; +} -- cgit v1.2.3