1 | ; Project name : Assembly Library |
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2 | ; Description : Functions to operate with |
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3 | ; 8254 Programmable Interval Timer. |
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4 | |
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5 | ; Section containing code |
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6 | SECTION .text |
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7 | |
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8 | ;-------------------------------------------------------------------- |
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9 | ; SystemTimer_IntializePreciseEventTimer |
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10 | ; Parameters: |
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11 | ; Nothing |
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12 | ; Returns: |
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13 | ; Nothing |
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14 | ; Corrupts registers: |
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15 | ; AX |
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16 | ;-------------------------------------------------------------------- |
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17 | ALIGN JUMP_ALIGN |
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18 | SystemTimer_IntializePreciseEventTimer: |
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19 | STOP_PRECISE_EVENT_TIMER |
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20 | OUTPUT_COUNTER_COMMAND_TO TIMER_2, READ_OR_WRITE_LSB_THEN_MSB, MODE_0_SINGLE_TIMEOUT, BINARY_COUNTER |
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21 | xor ax, ax |
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22 | WRITE_COUNT_FROM_AX_TO TIMER_2 |
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23 | ret |
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24 | |
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25 | |
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26 | ;-------------------------------------------------------------------- |
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27 | ; This is how to use precise event timer: |
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28 | ; 1. Call SystemTimer_IntializePreciseEventTimer |
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29 | ; 2. Use START_PRECISE_EVENT_TIMER macro to start timer |
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30 | ; 3. Use STOP_PRECISE_EVENT_TIMER to stop timer (optional) |
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31 | ; 4. Call SystemTimer_GetPreciseEventTimerTicksToAX to get event duration |
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32 | ; |
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33 | ; SystemTimer_GetPreciseEventTimerTicksToAX |
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34 | ; Parameters: |
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35 | ; Nothing |
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36 | ; Returns: |
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37 | ; AX: Event duration in timer ticks |
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38 | ; Corrupts registers: |
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39 | ; Nothing |
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40 | ;-------------------------------------------------------------------- |
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41 | ALIGN JUMP_ALIGN |
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42 | SystemTimer_GetPreciseEventTimerTicksToAX: |
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43 | OUTPUT_COUNTER_COMMAND_TO TIMER_2, LATCH, MODE_0_SINGLE_TIMEOUT, BINARY_COUNTER |
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44 | READ_COUNT_TO_AX_FROM TIMER_2 |
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45 | neg ax ; 0 - count (Mode 0 counts toward zero) |
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46 | ret |
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