5
Last change
on this file since 65f868c was
65f868c,
checked in by Sebastian Huber <sebastian.huber@…>, on 05/23/18 at 12:17:25
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Add _CPU_Counter_frequency()
Add rtems_counter_frequency() API function. Use it to initialize the
counter value converter via the new system initialization step
(RTEMS_SYSINIT_CPU_COUNTER). This decouples the counter implementation
and the counter converter. It avoids an unnecessary pull in of the
64-bit integer division from libgcc.
Update #3456.
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-
Property mode set to
100644
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File size:
1.3 KB
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1 | /* |
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2 | * Copyright (c) 2014, 2018 embedded brains GmbH. All rights reserved. |
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3 | * |
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4 | * embedded brains GmbH |
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5 | * Dornierstr. 4 |
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6 | * 82178 Puchheim |
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7 | * Germany |
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8 | * <rtems@embedded-brains.de> |
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9 | * |
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10 | * The license and distribution terms for this file may be |
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11 | * found in the file LICENSE in this distribution or at |
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12 | * http://www.rtems.org/license/LICENSE. |
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13 | */ |
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14 | |
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15 | #include <rtems/counter.h> |
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16 | #include <rtems/sysinit.h> |
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17 | |
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18 | RTEMS_STATIC_ASSERT(sizeof(rtems_counter_ticks) <= sizeof(uint32_t), type); |
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19 | |
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20 | static uint64_t to_ns_scaler; |
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21 | |
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22 | static uint64_t from_ns_scaler; |
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23 | |
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24 | uint64_t rtems_counter_ticks_to_nanoseconds( rtems_counter_ticks counter ) |
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25 | { |
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26 | return (uint32_t) ((counter * to_ns_scaler) >> 32); |
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27 | } |
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28 | |
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29 | rtems_counter_ticks rtems_counter_nanoseconds_to_ticks( uint32_t nanoseconds ) |
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30 | { |
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31 | return (rtems_counter_ticks) ((nanoseconds * from_ns_scaler) >> 32); |
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32 | } |
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33 | |
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34 | void rtems_counter_initialize_converter( uint32_t frequency ) |
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35 | { |
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36 | uint64_t ns_per_s = UINT64_C(1000000000); |
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37 | |
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38 | to_ns_scaler = ((ns_per_s << 32) + frequency - 1) / frequency; |
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39 | from_ns_scaler = ((UINT64_C(1) << 32) * frequency + ns_per_s - 1) / ns_per_s; |
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40 | } |
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41 | |
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42 | static void rtems_counter_sysinit( void ) |
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43 | { |
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44 | rtems_counter_initialize_converter( rtems_counter_frequency() ); |
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45 | } |
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46 | |
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47 | RTEMS_SYSINIT_ITEM( |
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48 | rtems_counter_sysinit, |
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49 | RTEMS_SYSINIT_CPU_COUNTER, |
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50 | RTEMS_SYSINIT_ORDER_LAST |
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51 | ); |
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