| 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_ReadNanosecsToDXAXfromPreciseEventTimer to get event duration
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| 32 | ;
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| 33 | ; SystemTimer_ReadNanosecsToDXAXfromPreciseEventTimer
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| 34 | ; Parameters:
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| 35 | ; Nothing
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| 36 | ; Returns:
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| 37 | ; DX:AX: Event duration in nanosecs
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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_ReadNanosecsToDXAXfromPreciseEventTimer:
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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 | mov dx, TIMER_CYCLE_TIME
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| 47 | mul dx
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| 48 | ret
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