| 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 | ;
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| 5 | ; XTIDE Universal BIOS and Associated Tools
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| 6 | ; Copyright (C) 2009-2010 by Tomi Tilli, 2011-2012 by XTIDE Universal BIOS Team.
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| 7 | ;
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| 8 | ; This program is free software; you can redistribute it and/or modify
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| 9 | ; it under the terms of the GNU General Public License as published by
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| 10 | ; the Free Software Foundation; either version 2 of the License, or
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| 11 | ; (at your option) any later version.
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| 12 | ;
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| 13 | ; This program is distributed in the hope that it will be useful,
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| 14 | ; but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 15 | ; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 16 | ; GNU General Public License for more details.
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| 17 | ; Visit http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
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| 18 | ;
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| 19 |
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| 20 | ; Section containing code
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| 21 | SECTION .text
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| 22 |
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| 23 | ;--------------------------------------------------------------------
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| 24 | ; Timer_InitializeTimeoutWithTicksInCL
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| 25 | ; Parameters:
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| 26 | ; CL: Timeout value in system timer ticks
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| 27 | ; DS: Segment to RAMVARS
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| 28 | ; Returns:
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| 29 | ; Nothing
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| 30 | ; Corrupts registers:
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| 31 | ; CX
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| 32 | ;--------------------------------------------------------------------
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| 33 | ALIGN JUMP_ALIGN
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| 34 | Timer_InitializeTimeoutWithTicksInCL:
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| 35 | mov [RAMVARS.bTimeoutTicksLeft], cl ; Ticks until timeout
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| 36 | call ReadTimeFromBdaToCX
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| 37 | mov [RAMVARS.bLastTimeoutUpdate], cl ; Start time
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| 38 | ret
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| 39 |
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| 40 |
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| 41 | ;--------------------------------------------------------------------
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| 42 | ; Timer_SetCFifTimeout
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| 43 | ; Parameters:
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| 44 | ; DS: Segment to RAMVARS
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| 45 | ; Returns:
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| 46 | ; CF: Set if timeout
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| 47 | ; Cleared if time left
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| 48 | ; Corrupts registers:
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| 49 | ; CX
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| 50 | ;--------------------------------------------------------------------
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| 51 | ALIGN JUMP_ALIGN
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| 52 | Timer_SetCFifTimeout:
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| 53 | call ReadTimeFromBdaToCX
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| 54 | cmp cl, [RAMVARS.bLastTimeoutUpdate]
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| 55 | je SHORT .StillPollingTheSameTick
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| 56 | mov [RAMVARS.bLastTimeoutUpdate], cl
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| 57 | sub BYTE [RAMVARS.bTimeoutTicksLeft], 1 ; DEC does not update CF
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| 58 | .StillPollingTheSameTick:
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| 59 | ret
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| 60 |
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| 61 |
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| 62 | ;--------------------------------------------------------------------
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| 63 | ; Delay is always at least one millisecond since
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| 64 | ; RTC resolution is 977 microsecs.
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| 65 | ;
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| 66 | ; Timer_DelayMicrosecondsFromAX
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| 67 | ; Parameters:
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| 68 | ; AX: Number of microsecs to wait
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| 69 | ; Returns:
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| 70 | ; Nothing
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| 71 | ; Corrupts registers:
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| 72 | ; AX
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| 73 | ;--------------------------------------------------------------------
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| 74 | Timer_DelayMicrosecondsFromAX:
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| 75 | %ifndef USE_AT
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| 76 | mov ax, 2
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| 77 | ; Fall to Timer_DelayTimerTicksFromAX
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| 78 | %else
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| 79 | push dx
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| 80 | push cx
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| 81 |
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| 82 | xor cx, cx
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| 83 | xchg dx, ax ; Microsecs now in CX:DX
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| 84 | mov ah, EVENT_WAIT
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| 85 | int BIOS_SYSTEM_INTERRUPT_15h
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| 86 | sti ; XT BIOSes return with interrupts disabled. TODO: Maybe we can remove this since it's in an AT-only block?
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| 87 |
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| 88 | pop cx
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| 89 | pop dx
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| 90 | mov ax, 1 ; Prepare to wait 1 timer tick
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| 91 | jc SHORT Timer_DelayTimerTicksFromAX ; Event Wait was unsupported or busy
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| 92 | ret
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| 93 | %endif
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| 94 |
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| 95 |
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| 96 | ;--------------------------------------------------------------------
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| 97 | ; First tick might take 0...54.9 ms and remaining ticks
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| 98 | ; will occur at 54.9 ms intervals.
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| 99 | ;
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| 100 | ; Timer_DelayTimerTicksFromAX
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| 101 | ; Parameters:
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| 102 | ; AX: Number of timer ticks to wait
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| 103 | ; Returns:
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| 104 | ; Nothing
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| 105 | ; Corrupts registers:
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| 106 | ; AX
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| 107 | ;--------------------------------------------------------------------
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| 108 | Timer_DelayTimerTicksFromAX:
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| 109 | sti ; Make sure that interrupts are enabled
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| 110 | call ReadTimeFromBdaToCX
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| 111 | add ax, cx ; AX = end time
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| 112 | .WaitLoop:
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| 113 | call ReadTimeFromBdaToCX
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| 114 | cmp cx, ax
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| 115 | jne SHORT .WaitLoop ; Loop until end time is reached
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| 116 | ret
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| 117 |
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| 118 |
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| 119 | ;--------------------------------------------------------------------
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| 120 | ; ReadTimeFromBdaToCX
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| 121 | ; Parameters
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| 122 | ; Nothing
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| 123 | ; Returns:
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| 124 | ; CX: System time in 54.9 ms ticks
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| 125 | ; Corrupts registers:
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| 126 | ; Nothing
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| 127 | ;--------------------------------------------------------------------
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| 128 | ALIGN JUMP_ALIGN
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| 129 | ReadTimeFromBdaToCX:
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| 130 | push ds
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| 131 | LOAD_BDA_SEGMENT_TO ds, cx
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| 132 | mov cx, [BDA.dwTimerTicks] ; Read low WORD only
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| 133 | pop ds
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| 134 | ret
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