| [140] | 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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| [155] | 8 | ; Timer_InitializeTimeoutWithTicksInCL
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| [140] | 9 | ; Parameters:
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| [155] | 10 | ; CL: Timeout value in system timer ticks
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| [140] | 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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| [155] | 18 | Timer_InitializeTimeoutWithTicksInCL:
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| 19 | mov [RAMVARS.bTimeoutTicksLeft], cl ; Ticks until timeout
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| [140] | 20 | call ReadTimeFromBdaToCX
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| [155] | 21 | mov [RAMVARS.bLastTimeoutUpdate], cl ; Start time
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| [140] | 22 | ret
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| 23 |
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| 24 |
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| 25 | ;--------------------------------------------------------------------
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| [155] | 26 | ; Timer_SetCFifTimeout
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| [140] | 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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| [155] | 36 | Timer_SetCFifTimeout:
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| [140] | 37 | call ReadTimeFromBdaToCX
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| [155] | 38 | cmp cl, [RAMVARS.bLastTimeoutUpdate]
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| 39 | je SHORT .StillPollingTheSameTick
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| 40 | mov [RAMVARS.bLastTimeoutUpdate], cl
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| 41 | sub BYTE [RAMVARS.bTimeoutTicksLeft], 1 ; DEC does not update CF
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| 42 | .StillPollingTheSameTick:
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| [140] | 43 | ret
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| 44 |
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| 45 |
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| 46 | ;--------------------------------------------------------------------
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| 47 | ; Delay is always at least one millisecond since
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| 48 | ; RTC resolution is 977 microsecs.
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| 49 | ;
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| [155] | 50 | ; Timer_DelayMicrosecondsFromAX
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| [140] | 51 | ; Parameters:
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| 52 | ; AX: Number of microsecs to wait
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| 53 | ; Returns:
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| 54 | ; Nothing
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| 55 | ; Corrupts registers:
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| 56 | ; AX
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| 57 | ;--------------------------------------------------------------------
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| [155] | 58 | Timer_DelayMicrosecondsFromAX:
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| [140] | 59 | %ifndef USE_AT
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| [150] | 60 | mov ax, 2
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| [140] | 61 | ; Fall to Delay_TimerTicksFromAX
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| 62 | %else
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| 63 | push dx
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| 64 | push cx
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| 65 |
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| 66 | xor cx, cx
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| [148] | 67 | xchg dx, ax ; Microsecs now in CX:DX
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| [140] | 68 | mov ah, EVENT_WAIT
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| 69 | int BIOS_SYSTEM_INTERRUPT_15h
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| [148] | 70 | sti ; XT BIOSes return with interrupt disabled
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| [140] | 71 |
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| 72 | pop cx
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| 73 | pop dx
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| [148] | 74 | mov ax, 1 ; Prepare to wait 1 timer tick
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| [155] | 75 | jc SHORT Timer_DelayTimerTicksFromAX ; Event Wait was unsupported or busy
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| [140] | 76 | ret
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| 77 | %endif
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| 78 |
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| 79 |
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| 80 | ;--------------------------------------------------------------------
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| 81 | ; First tick might take 0...54.9 ms and remaining ticks
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| 82 | ; will occur at 54.9 ms intervals.
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| 83 | ;
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| [155] | 84 | ; Timer_DelayTimerTicksFromAX
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| [140] | 85 | ; Parameters:
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| 86 | ; AX: Number of timer ticks to wait
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| 87 | ; Returns:
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| 88 | ; Nothing
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| 89 | ; Corrupts registers:
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| 90 | ; AX
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| 91 | ;--------------------------------------------------------------------
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| [155] | 92 | Timer_DelayTimerTicksFromAX:
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| [140] | 93 | sti ; Make sure that interrupts are enabled
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| 94 | call ReadTimeFromBdaToCX
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| 95 | add ax, cx ; AX = end time
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| 96 | .WaitLoop:
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| 97 | call ReadTimeFromBdaToCX
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| 98 | cmp cx, ax
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| [155] | 99 | jne SHORT .WaitLoop ; Loop until end time is reached
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| [140] | 100 | ret
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| 101 |
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| 102 |
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| 103 | ;--------------------------------------------------------------------
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| 104 | ; ReadTimeFromBdaToCX
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| 105 | ; Parameters
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| 106 | ; Nothing
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| 107 | ; Returns:
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| 108 | ; CX: System time in 54.9 ms ticks
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| 109 | ; Corrupts registers:
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| 110 | ; Nothing
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| 111 | ;--------------------------------------------------------------------
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| 112 | ALIGN JUMP_ALIGN
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| 113 | ReadTimeFromBdaToCX:
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| 114 | push ds
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| 115 | LOAD_BDA_SEGMENT_TO ds, cx
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| 116 | mov cx, [BDA.dwTimerTicks] ; Read low WORD only
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| 117 | pop ds
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| 118 | ret
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