| 1 | ; Project name : XTIDE Universal BIOS
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| 2 | ; Description : Int 13h handler that is used by MODULE_MFM_COMPATIBILITY.
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| 3 | ; It is placed between XTUB Int 13h hander and system INT 13h hander
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| 4 | ; to hide XTUB from MFM controllers whose BIOS assumes they handler
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| 5 | ; all hard drives on the system.
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| 6 |
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| 7 | ;
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| 8 | ; XTIDE Universal BIOS and Associated Tools
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| 9 | ; Copyright (C) 2009-2010 by Tomi Tilli, 2011-2013 by XTIDE Universal BIOS Team.
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| 10 | ;
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| 11 | ; This program is free software; you can redistribute it and/or modify
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| 12 | ; it under the terms of the GNU General Public License as published by
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| 13 | ; the Free Software Foundation; either version 2 of the License, or
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| 14 | ; (at your option) any later version.
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| 15 | ;
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| 16 | ; This program is distributed in the hope that it will be useful,
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| 17 | ; but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 18 | ; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 19 | ; GNU General Public License for more details.
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| 20 | ; Visit http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
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| 21 | ;
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| 22 |
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| 23 | ; Section containing code
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| 24 | SECTION .text
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| 25 |
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| 26 |
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| 27 | ;--------------------------------------------------------------------
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| 28 | ; Int 13h software interrupt handler for MFM compatibility.
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| 29 | ;
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| 30 | ; Some MDM controllers require that BDA drive count is what they have set.
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| 31 | ; The purpose for this handler is to restore BDA drive count to what MFM controller
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| 32 | ; expects and then call MFM controller INT 13h.
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| 33 | ;
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| 34 | ; Int13hMFMcompatibilityHandler
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| 35 | ; Parameters:
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| 36 | ; Any INT 13h function and parameters
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| 37 | ;--------------------------------------------------------------------
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| 38 | ALIGN JUMP_ALIGN
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| 39 | Int13hMFMcompatibilityHandler:
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| 40 | eENTER 6, 0
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| 41 | push es
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| 42 | push ds
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| 43 | push di
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| 44 |
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| 45 | LOAD_BDA_SEGMENT_TO es, di
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| 46 | call RamVars_GetSegmentToDS
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| 47 |
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| 48 | ; Remove our drives from BDA drive count
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| 49 | push ax
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| 50 | mov al, [RAMVARS.bDrvCnt]
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| 51 | mov [bp-2], al ; Store our drive count for later use
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| 52 | sub [es:HDBDA.bHDCount], al
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| 53 | pop ax
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| 54 |
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| 55 | ; Copy MFM controller INT 13h address to stack
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| 56 | les di, [RAMVARS.fpMFMint13h]
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| 57 | mov [bp-4], es
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| 58 | mov [bp-6], di
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| 59 |
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| 60 | ; Restore registers so we can call MFM int 13h
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| 61 | pop di
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| 62 | pop ds
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| 63 | pop es
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| 64 |
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| 65 | pushf ; Push flags to simulate INT
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| 66 | call far [bp-6]
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| 67 |
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| 68 | ; Now we can restore BDA drive count
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| 69 | push ds
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| 70 | push ax
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| 71 | lahf ; Get return flags to AH
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| 72 | mov [bp-12], ah ; Store return flags to be popped by iret
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| 73 | LOAD_BDA_SEGMENT_TO ds, ax
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| 74 | mov al, [bp-2]
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| 75 | add [HDBDA.bHDCount], al
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| 76 | pop ax
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| 77 | pop ds
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| 78 |
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| 79 | ; Return from this handler
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| 80 | eLEAVE
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| 81 | iret
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