| 1 | ; Project name : Assembly Library
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| 2 | ; Description : Delay functions.
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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 | ; Delay is always at least one millisecond since
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| 25 | ; RTC resolution is 977 microsecs.
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| 26 | ;
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| 27 | ; Delay_MicrosecondsFromAX
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| 28 | ; Parameters:
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| 29 | ; AX: Number of microsecs to wait
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| 30 | ; Returns:
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| 31 | ; Nothing
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| 32 | ; Corrupts registers:
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| 33 | ; AX
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| 34 | ;--------------------------------------------------------------------
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| 35 | ALIGN JUMP_ALIGN
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| 36 | Delay_MicrosecondsFromAX:
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| 37 | push dx
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| 38 | push cx
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| 39 |
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| 40 | xor cx, cx
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| 41 | xchg dx, ax ; Microsecs now in CX:DX
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| 42 | mov ah, EVENT_WAIT ; Event Wait
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| 43 | int BIOS_SYSTEM_INTERRUPT_15h
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| 44 | sti ; XT BIOSes return with interrupt disabled
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| 45 |
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| 46 | pop cx
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| 47 | pop dx
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| 48 | mov ax, 1 ; Prepare to wait 1 timer tick
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| 49 | jc SHORT Delay_TimerTicksFromAX ; Event Wait was unsupported or busy
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| 50 | ret
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| 51 |
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| 52 |
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| 53 | ;--------------------------------------------------------------------
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| 54 | ; First tick might take 0...54.9 ms and remaining ticks
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| 55 | ; will occur at 54.9 ms intervals.
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| 56 | ;
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| 57 | ; Delay_TimerTicksFromAX
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| 58 | ; Parameters:
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| 59 | ; AX: Number of timer ticks to wait
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| 60 | ; Returns:
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| 61 | ; Nothing
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| 62 | ; Corrupts registers:
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| 63 | ; AX
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| 64 | ;--------------------------------------------------------------------
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| 65 | ALIGN JUMP_ALIGN
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| 66 | Delay_TimerTicksFromAX:
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| 67 | push dx
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| 68 |
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| 69 | sti ; Make sure that interrupts are enabled
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| 70 | xchg dx, ax
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| 71 | call TimerTicks_ReadFromBdaToAX
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| 72 | add dx, ax ; DX = end time
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| 73 | .WaitLoop:
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| 74 | call TimerTicks_ReadFromBdaToAX
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| 75 | cmp ax, dx
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| 76 | jb SHORT .WaitLoop ; Loop until end time is reached
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| 77 |
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| 78 | pop dx
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| 79 | ret
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