1 | /* |
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2 | * This file implements a benchmark timer using a TX39 timer. |
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3 | * |
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4 | * NOTE: On the simulator, the count directly reflects instructions. |
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5 | * |
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6 | * COPYRIGHT (c) 1989-2000. |
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7 | * On-Line Applications Research Corporation (OAR). |
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8 | * |
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9 | * The license and distribution terms for this file may be |
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10 | * found in found in the file LICENSE in this distribution or at |
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11 | * http://www.rtems.com/license/LICENSE. |
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12 | * |
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13 | * $Id$ |
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14 | */ |
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15 | |
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16 | #include <assert.h> |
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17 | |
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18 | #include <bsp.h> |
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19 | |
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20 | rtems_boolean benchmark_timerfind_average_overhead; |
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21 | |
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22 | void benchmark_timerinitialize(void) |
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23 | { |
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24 | /* |
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25 | * Programming the compare register as the maximum value should let |
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26 | * it run long enough and accurate enough not to require an interrupt. |
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27 | * but if it ever does generate an interrupt, we will simply fault. |
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28 | * |
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29 | * NOTE: This is similar to the clock driver initialization |
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30 | * with the exception that the divider is disabled and |
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31 | * the compare register is set to the maximum value. |
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32 | */ |
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33 | |
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34 | TX3904_TIMER_WRITE( TX3904_TIMER1_BASE, TX3904_TIMER_TCR, 0x20 ); |
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35 | TX3904_TIMER_WRITE( TX3904_TIMER1_BASE, TX3904_TIMER_CCDR, 0x3 ); |
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36 | TX3904_TIMER_WRITE( TX3904_TIMER1_BASE, TX3904_TIMER_TRR, 0x0 ); |
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37 | TX3904_TIMER_WRITE( TX3904_TIMER1_BASE, TX3904_TIMER_CPRA, 0xFFFFFFFF ); |
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38 | TX3904_TIMER_WRITE( TX3904_TIMER1_BASE, TX3904_TIMER_TISR, 0x00 ); |
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39 | TX3904_TIMER_WRITE( TX3904_TIMER1_BASE, TX3904_TIMER_ITMR, 0x0001 ); |
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40 | TX3904_TIMER_WRITE( TX3904_TIMER1_BASE, TX3904_TIMER_TCR, 0xe0 ); |
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41 | } |
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42 | |
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43 | #define AVG_OVERHEAD 0 /* It typically takes N instructions */ |
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44 | /* to start/stop the timer. */ |
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45 | #define LEAST_VALID 1 /* Don't trust a value lower than this */ |
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46 | /* tx39 simulator can count instructions. :) */ |
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47 | |
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48 | int benchmark_timerread(void) |
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49 | { |
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50 | uint32_t total; |
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51 | |
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52 | total = TX3904_TIMER_READ( TX3904_TIMER1_BASE, TX3904_TIMER_TRR ); |
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53 | |
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54 | if ( benchmark_timerfind_average_overhead == 1 ) |
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55 | return total; /* in one microsecond units */ |
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56 | |
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57 | if ( total < LEAST_VALID ) |
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58 | return 0; /* below timer resolution */ |
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59 | |
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60 | return total - AVG_OVERHEAD; |
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61 | } |
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62 | |
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63 | rtems_status_code benchmark_timerempty_function( void ) |
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64 | { |
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65 | return RTEMS_SUCCESSFUL; |
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66 | } |
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67 | |
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68 | void benchmark_timerdisable_subtracting_average_overhead( |
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69 | rtems_boolean find_flag |
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70 | ) |
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71 | { |
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72 | benchmark_timerfind_average_overhead = find_flag; |
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73 | } |
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