root / lab2 / timer.h @ 13
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| 1 | 6 | up20180645 | #ifndef __TIMER_H
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| 2 | #define __TIMER_H
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| 3 | |||
| 4 | /**
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| 5 | * @brief Enumerated type for specifying the timer value initialization
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| 6 | */
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| 7 | enum timer_init {
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| 8 | INVAL_val, /*!< Invalid initialization mode */
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| 9 | LSB_only, /*!< Initialization only of the LSB */
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| 10 | MSB_only, /*!< Initialization only of the MSB */
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| 11 | MSB_after_LSB /*!< Initialization of LSB and MSB, in this order */
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| 12 | }; |
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| 13 | |||
| 14 | /**
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| 15 | * @brief Enumerated type for identifying the timer status fields
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| 16 | */
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| 17 | enum timer_status_field {
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| 18 | tsf_all, /*!< configuration/status */
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| 19 | tsf_initial, /*!< timer initialization mode */
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| 20 | tsf_mode, /*!< timer counting mode */
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| 21 | tsf_base /*!< timer counting base */
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| 22 | }; |
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| 23 | |||
| 24 | /**
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| 25 | * @brief Union for storing values of timer status fields, including the full status byte
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| 26 | */
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| 27 | union timer_status_field_val {
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| 28 | uint8_t byte; /*!< status */
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| 29 | enum timer_init in_mode; /*!< initialization mode */ |
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| 30 | uint8_t count_mode; /*!< counting mode: 0, 1,.., 5 */
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| 31 | bool bcd; /*!< counting base, true if BCD */ |
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| 32 | }; |
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| 33 | |||
| 34 | /**
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| 35 | * @brief Changes the operating frequency of a timer
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| 36 | *
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| 37 | * Must use the read-back command so that it does not change
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| 38 | * the 4 LSBs (mode and BCD/binary) of the timer's control word.
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| 39 | *
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| 40 | * @param timer Timer to configure. (Ranges from 0 to 2)
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| 41 | * @param freq Timer operating frequency
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| 42 | * @return Return 0 upon success and non-zero otherwise
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| 43 | */
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| 44 | int(timer_set_frequency)(uint8_t timer, uint32_t freq);
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| 45 | |||
| 46 | /**
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| 47 | * @brief Subscribes and enables Timer 0 interrupts
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| 48 | *
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| 49 | * @param bit_no address of memory to be initialized with the
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| 50 | * bit number to be set in the mask returned upon an interrupt
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| 51 | * @return Return 0 upon success and non-zero otherwise
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| 52 | */
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| 53 | int(timer_subscribe_int)(uint8_t *bit_no);
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| 54 | |||
| 55 | /**
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| 56 | * @brief Unsubscribes Timer 0 interrupts
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| 57 | *
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| 58 | * @return Return 0 upon success and non-zero otherwise
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| 59 | */
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| 60 | int(timer_unsubscribe_int)();
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| 61 | |||
| 62 | /**
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| 63 | * @brief Timer 0 interrupt handler
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| 64 | *
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| 65 | * Increments counter
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| 66 | */
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| 67 | void(timer_int_handler)();
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| 68 | |||
| 69 | /**
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| 70 | * @brief Reads the input timer configuration (status) via read-back command
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| 71 | *
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| 72 | * @param timer Timer whose configuration to read (Ranges from 0 to 2)
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| 73 | * @param st Address of memory position to be filled with the timer config
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| 74 | * @return Return 0 upon success and non-zero otherwise
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| 75 | */
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| 76 | int(timer_get_conf)(uint8_t timer, uint8_t *st);
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| 77 | |||
| 78 | /**
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| 79 | * @brief Shows timer configuration
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| 80 | *
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| 81 | #include <stdbool.h>
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| 82 | #include <stdint.h>
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| 83 | |||
| 84 | /** @defgroup timer timer
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| 85 | * @{
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| 86 | *
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| 87 | * Functions for using the i8254 timers
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| 88 | */
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| 89 | |||
| 90 | /** Displays, in a human friendly way, the specified field of a
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| 91 | * timer status, which was read via the read-back command
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| 92 | *
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| 93 | * @param timer timer whose configuration should be displayed (Ranges from 0 to 2)
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| 94 | * @param st status read via the read-back command
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| 95 | * @param field status field to display in human friendly way
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| 96 | * @return Return 0 upon success and non-zero otherwise
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| 97 | */
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| 98 | int(timer_display_conf)(uint8_t timer, uint8_t st, enum timer_status_field field); |
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| 99 | |||
| 100 | /**
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| 101 | * @brief Prints a timer config field value
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| 102 | *
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| 103 | * @return Returns 0 upon success and non-zero otherwise
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| 104 | */
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| 105 | int(timer_print_config)(uint8_t timer, enum timer_status_field field, |
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| 106 | union timer_status_field_val val);
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| 107 | |||
| 108 | /**
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| 109 | * @brief Increments elapsed time count
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| 110 | *
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| 111 | * @return Returns the current time count
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| 112 | */
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| 113 | uint32_t(timer_print_elapsed_time)(); |
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| 114 | |||
| 115 | #endif /* __TIMER_H */ |