1 | /* Timer_init() |
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2 | * |
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3 | * This routine initializes the timer on the FORCE CPU-386 board. |
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4 | * |
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5 | * Input parameters: NONE |
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6 | * |
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7 | * Output parameters: NONE |
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8 | * |
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9 | * NOTE: This routine will not work if the optimizer is enabled |
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10 | * for some compilers. The multiple writes to the Z8036 |
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11 | * may be optimized away. |
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12 | * |
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13 | * It is important that the timer start/stop overhead be |
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14 | * determined when porting or modifying this code. |
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15 | * |
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16 | * COPYRIGHT (c) 1989-1998. |
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17 | * On-Line Applications Research Corporation (OAR). |
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18 | * Copyright assigned to U.S. Government, 1994. |
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19 | * |
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20 | * The license and distribution terms for this file may be |
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21 | * found in the file LICENSE in this distribution or at |
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22 | * http://www.OARcorp.com/rtems/license.html. |
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23 | * |
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24 | * $Id$ |
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25 | */ |
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26 | |
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27 | |
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28 | #include <rtems.h> |
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29 | #include <bsp.h> |
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30 | |
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31 | int Ttimer_val; |
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32 | rtems_boolean Timer_driver_Find_average_overhead; |
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33 | |
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34 | rtems_isr timerisr(); |
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35 | |
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36 | #define TMR0 0xF040 |
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37 | #define TMR1 0xF041 |
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38 | #define TMR2 0xF042 |
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39 | #define TMRCON 0xF043 |
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40 | #define TMRCFG 0xF834 |
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41 | |
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42 | void Timer_initialize() |
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43 | { |
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44 | |
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45 | (void) set_vector( timerisr, 0x2a, 0 ); /* install ISR ( IR2 ) was 0x38*/ |
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46 | |
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47 | Ttimer_val = 0; /* clear timer ISR count */ |
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48 | |
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49 | outport_byte ( TMRCON , 0xb0 ); /* select tmr2, stay in mode 0 */ |
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50 | outport_byte ( TMR1 , 0xd2 ); /* set to 250 usec interval */ |
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51 | outport_byte ( TMR1 , 0x00 ); |
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52 | outport_byte ( TMRCON , 0x64 ); /* change to mode 2 ( starts timer ) */ |
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53 | /* interrupts ARE enabled */ |
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54 | /* outport_byte( IERA, 0x41 ); enable interrupt */ |
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55 | |
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56 | } |
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57 | |
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58 | #define AVG_OVERHEAD 3 /* It typically takes 3.0 microseconds */ |
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59 | /* (3 ticks) to start/stop the timer. */ |
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60 | #define LEAST_VALID 4 /* Don't trust a value lower than this */ |
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61 | |
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62 | int Read_timer() |
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63 | { |
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64 | register rtems_unsigned32 clicks; |
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65 | register rtems_unsigned32 total; |
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66 | |
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67 | /* outport_byte( TBCR, 0x00 ); stop the timer -- not needed on intel */ |
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68 | |
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69 | outport_byte ( TMRCON, 0x40 ); /* latch the count */ |
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70 | inport_byte ( TMR1, clicks ); /* read the count */ |
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71 | |
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72 | total = Ttimer_val + 250 - clicks; |
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73 | |
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74 | /* outport_byte( TBCR, 0x00 ); initial value */ |
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75 | /* outport_byte( IERA, 0x40 ); disable interrupt */ |
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76 | |
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77 | /* ??? Is "do not restore old vector" causing problems? */ |
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78 | |
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79 | if ( Timer_driver_Find_average_overhead == 1 ) |
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80 | return total; /* in one microsecond units */ |
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81 | |
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82 | else { |
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83 | if ( total < LEAST_VALID ) |
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84 | return 0; /* below timer resolution */ |
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85 | return (total - AVG_OVERHEAD); |
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86 | } |
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87 | } |
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88 | |
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89 | rtems_status_code Empty_function( void ) |
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90 | { |
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91 | return RTEMS_SUCCESSFUL; |
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92 | } |
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93 | |
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94 | void Set_find_average_overhead( |
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95 | rtems_boolean find_flag |
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96 | ) |
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97 | { |
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98 | Timer_driver_Find_average_overhead = find_flag; |
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99 | } |
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