| 1 | ; Project name : XTIDE Universal BIOS
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| 2 | ; Description : Timeout and delay functions for INT 13h services.
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| 3 |
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| 4 | ; Section containing code
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| 5 | SECTION .text
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| 6 |
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| 7 | ;--------------------------------------------------------------------
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| 8 | ; HTimer_InitializeTimeoutWithTicksInCX
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| 9 | ; Parameters:
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| 10 | ; CX: Timeout value in system timer ticks
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| 11 | ; DS: Segment to RAMVARS
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| 12 | ; Returns:
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| 13 | ; Nothing
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| 14 | ; Corrupts registers:
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| 15 | ; CX
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| 16 | ;--------------------------------------------------------------------
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| 17 | ALIGN JUMP_ALIGN
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| 18 | HTimer_InitializeTimeoutWithTicksInCX:
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| 19 | mov [RAMVARS.wTimeoutCounter], cx ; Store timeout ticks
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| 20 | call ReadTimeFromBdaToCX
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| 21 | add [RAMVARS.wTimeoutCounter], cx ; End time for timeout
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| 22 | ret
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| 23 |
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| 24 |
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| 25 | ;--------------------------------------------------------------------
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| 26 | ; HTimer_SetCFifTimeout
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| 27 | ; Parameters:
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| 28 | ; DS: Segment to RAMVARS
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| 29 | ; Returns:
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| 30 | ; CF: Set if timeout
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| 31 | ; Cleared if time left
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| 32 | ; Corrupts registers:
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| 33 | ; CX
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| 34 | ;--------------------------------------------------------------------
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| 35 | ALIGN JUMP_ALIGN
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| 36 | HTimer_SetCFifTimeout:
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| 37 | call ReadTimeFromBdaToCX
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| 38 | cmp [RAMVARS.wTimeoutCounter], cx
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| 39 | ret
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| 40 |
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| 41 |
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| 42 | ;--------------------------------------------------------------------
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| 43 | ; Delay is always at least one millisecond since
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| 44 | ; RTC resolution is 977 microsecs.
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| 45 | ;
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| 46 | ; HTimer_DelayMicrosecondsFromAX
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| 47 | ; Parameters:
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| 48 | ; AX: Number of microsecs to wait
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| 49 | ; Returns:
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| 50 | ; Nothing
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| 51 | ; Corrupts registers:
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| 52 | ; AX
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| 53 | ;--------------------------------------------------------------------
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| 54 | HTimer_DelayMicrosecondsFromAX:
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| 55 | %ifndef USE_AT
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| 56 | mov ax, 2
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| 57 | ; Fall to Delay_TimerTicksFromAX
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| 58 | %else
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| 59 | push dx
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| 60 | push cx
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| 61 |
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| 62 | xor cx, cx
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| 63 | xchg dx, ax ; Microsecs now in CX:DX
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| 64 | mov ah, EVENT_WAIT
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| 65 | int BIOS_SYSTEM_INTERRUPT_15h
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| 66 | sti ; XT BIOSes return with interrupt disabled
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| 67 |
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| 68 | pop cx
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| 69 | pop dx
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| 70 | mov ax, 1 ; Prepare to wait 1 timer tick
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| 71 | jc SHORT HTimer_DelayTimerTicksFromAX ; Event Wait was unsupported or busy
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| 72 | ret
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| 73 | %endif
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| 74 |
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| 75 |
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| 76 | ;--------------------------------------------------------------------
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| 77 | ; First tick might take 0...54.9 ms and remaining ticks
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| 78 | ; will occur at 54.9 ms intervals.
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| 79 | ;
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| 80 | ; HTimer_DelayTimerTicksFromAX
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| 81 | ; Parameters:
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| 82 | ; AX: Number of timer ticks to wait
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| 83 | ; Returns:
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| 84 | ; Nothing
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| 85 | ; Corrupts registers:
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| 86 | ; AX
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| 87 | ;--------------------------------------------------------------------
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| 88 | HTimer_DelayTimerTicksFromAX:
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| 89 | sti ; Make sure that interrupts are enabled
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| 90 | call ReadTimeFromBdaToCX
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| 91 | add ax, cx ; AX = end time
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| 92 | .WaitLoop:
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| 93 | call ReadTimeFromBdaToCX
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| 94 | cmp cx, ax
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| 95 | jb SHORT .WaitLoop ; Loop until end time is reached
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| 96 | ret
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| 97 |
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| 98 |
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| 99 | ;--------------------------------------------------------------------
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| 100 | ; ReadTimeFromBdaToCX
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| 101 | ; Parameters
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| 102 | ; Nothing
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| 103 | ; Returns:
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| 104 | ; CX: System time in 54.9 ms ticks
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| 105 | ; Corrupts registers:
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| 106 | ; Nothing
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| 107 | ;--------------------------------------------------------------------
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| 108 | ALIGN JUMP_ALIGN
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| 109 | ReadTimeFromBdaToCX:
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| 110 | push ds
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| 111 | LOAD_BDA_SEGMENT_TO ds, cx
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| 112 | mov cx, [BDA.dwTimerTicks] ; Read low WORD only
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| 113 | pop ds
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| 114 | ret
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