1 | /* timer.c |
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2 | * |
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3 | * This file implements a benchmark timer using timer 2. |
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4 | * |
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5 | * COPYRIGHT (c) 1989-1998. |
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6 | * On-Line Applications Research Corporation (OAR). |
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7 | * |
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8 | * The license and distribution terms for this file may be |
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9 | * found in the file LICENSE in this distribution or at |
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10 | * http://www.rtems.com/license/LICENSE. |
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11 | * |
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12 | * Ported to LEON implementation of the SPARC by On-Line Applications |
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13 | * Research Corporation (OAR) under contract to the European Space |
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14 | * Agency (ESA). |
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15 | * |
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16 | * LEON modifications of respective RTEMS file: COPYRIGHT (c) 1995. |
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17 | * European Space Agency. |
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18 | * |
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19 | * $Id$ |
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20 | */ |
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21 | |
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22 | |
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23 | #include <bsp.h> |
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24 | |
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25 | rtems_boolean benchmark_timerfind_average_overhead; |
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26 | |
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27 | rtems_boolean benchmark_timeris_initialized = FALSE; |
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28 | |
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29 | void benchmark_timerinitialize(void) |
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30 | { |
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31 | /* |
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32 | * Timer runs long and accurate enough not to require an interrupt. |
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33 | */ |
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34 | |
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35 | if ( benchmark_timeris_initialized == FALSE ) { |
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36 | |
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37 | /* approximately 1 us per countdown */ |
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38 | LEON_REG.Timer_Counter_2 = 0xffffff; |
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39 | LEON_REG.Timer_Reload_2 = 0xffffff; |
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40 | |
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41 | } else { |
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42 | benchmark_timeris_initialized = TRUE; |
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43 | } |
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44 | |
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45 | LEON_REG.Timer_Control_2 = ( |
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46 | LEON_REG_TIMER_COUNTER_ENABLE_COUNTING | |
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47 | LEON_REG_TIMER_COUNTER_LOAD_COUNTER |
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48 | ); |
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49 | |
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50 | } |
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51 | |
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52 | #define AVG_OVERHEAD 3 /* It typically takes 3.0 microseconds */ |
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53 | /* to start/stop the timer. */ |
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54 | #define LEAST_VALID 2 /* Don't trust a value lower than this */ |
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55 | |
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56 | int benchmark_timerread(void) |
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57 | { |
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58 | uint32_t total; |
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59 | |
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60 | total = LEON_REG.Timer_Counter_2; |
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61 | |
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62 | total = 0xffffff - total; |
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63 | |
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64 | if ( benchmark_timerfind_average_overhead == 1 ) |
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65 | return total; /* in one microsecond units */ |
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66 | |
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67 | if ( total < LEAST_VALID ) |
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68 | return 0; /* below timer resolution */ |
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69 | |
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70 | return total - AVG_OVERHEAD; |
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71 | } |
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72 | |
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73 | rtems_status_code benchmark_timerempty_function( void ) |
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74 | { |
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75 | return RTEMS_SUCCESSFUL; |
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76 | } |
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77 | |
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78 | void benchmark_timerdisable_subtracting_average_overhead( |
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79 | rtems_boolean find_flag |
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80 | ) |
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81 | { |
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82 | benchmark_timerfind_average_overhead = find_flag; |
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83 | } |
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