| 1 | ; Project name : XTIDE Universal BIOS
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| 2 | ; Description : Functions for swapping drive letters.
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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 | ; DriveXlate_ToOrBack
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| 9 | ; Parameters:
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| 10 | ; DL: Drive number to be possibly translated
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| 11 | ; DS: RAMVARS segment
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| 12 | ; Returns:
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| 13 | ; DL: Translated drive number
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| 14 | ; Corrupts registers:
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| 15 | ; DI
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| 16 | ;--------------------------------------------------------------------
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| 17 | ALIGN JUMP_ALIGN
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| 18 | DriveXlate_ToOrBack:
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| 19 | test BYTE [cs:ROMVARS.wFlags], FLG_ROMVARS_DRVXLAT
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| 20 | jz SHORT .Return ; Return if translation disabled
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| 21 | xchg di, ax ; Backup AX
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| 22 | call SwapFloppyDriveOrHardDisk
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| 23 | xchg ax, di
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| 24 | .Return:
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| 25 | ret
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| 26 |
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| 27 |
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| 28 | ;--------------------------------------------------------------------
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| 29 | ; SwapFloppyDriveOrHardDisk
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| 30 | ; Parameters:
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| 31 | ; DL: Drive number to be possibly swapped
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| 32 | ; DS: RAMVARS segment
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| 33 | ; Returns:
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| 34 | ; DL: Translated drive number
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| 35 | ; Corrupts registers:
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| 36 | ; AX
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| 37 | ;--------------------------------------------------------------------
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| 38 | ALIGN JUMP_ALIGN
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| 39 | SwapFloppyDriveOrHardDisk:
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| 40 | mov ah, 80h ; Assume hard disk
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| 41 | mov al, BYTE [RAMVARS.xlateVars+XLATEVARS.bHDSwap]
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| 42 | test dl, ah ; Hard disk?
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| 43 | jnz SHORT SwapDrive ; If so, jump to swap
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| 44 | mov al, BYTE [RAMVARS.xlateVars+XLATEVARS.bFDSwap]
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| 45 | cbw
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| 46 | ; Fall to SwapDrive
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| 47 |
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| 48 | ;--------------------------------------------------------------------
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| 49 | ; SwapDrive
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| 50 | ; Parameters:
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| 51 | ; AL: Drive number to swap to 00h/80h
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| 52 | ; AH: 00h/80h to be swapped to stored drive number
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| 53 | ; DL: Drive number to be possibly swapped
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| 54 | ; Returns:
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| 55 | ; DL: Translated drive number
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| 56 | ; Corrupts registers:
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| 57 | ; Nothing
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| 58 | ;--------------------------------------------------------------------
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| 59 | ALIGN JUMP_ALIGN
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| 60 | SwapDrive:
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| 61 | cmp ah, dl ; Swap DL from 00h/80h to xxh?
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| 62 | je SHORT .SwapToXXhInAL
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| 63 | cmp al, dl ; Swap DL from xxh to 00h/80h?
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| 64 | je SHORT .SwapTo00hOr80hInAH
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| 65 | ret
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| 66 | ALIGN JUMP_ALIGN
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| 67 | .SwapTo00hOr80hInAH:
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| 68 | mov dl, ah
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| 69 | ret
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| 70 | ALIGN JUMP_ALIGN
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| 71 | .SwapToXXhInAL:
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| 72 | mov dl, al
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| 73 | ret
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| 74 |
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| 75 |
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| 76 | ;--------------------------------------------------------------------
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| 77 | ; Resets drive swapping variables to defaults (no swapping).
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| 78 | ;
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| 79 | ; DriveXlate_Reset
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| 80 | ; Parameters:
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| 81 | ; DS: RAMVARS segment
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| 82 | ; Returns:
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| 83 | ; Nothing
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| 84 | ; Corrupts registers:
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| 85 | ; AX
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| 86 | ;--------------------------------------------------------------------
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| 87 | ALIGN JUMP_ALIGN
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| 88 | DriveXlate_Reset:
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| 89 | mov WORD [RAMVARS.xlateVars], 8000h ; .bFDSwap and .bHDSwap
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| 90 | ret
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| 91 |
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| 92 |
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| 93 | ;--------------------------------------------------------------------
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| 94 | ; Stores drive to be swapped.
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| 95 | ;
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| 96 | ; DriveXlate_SetDriveToSwap
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| 97 | ; Parameters:
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| 98 | ; DL: Drive to swap to 00h or 80h
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| 99 | ; DS: RAMVARS segment
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| 100 | ; Returns:
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| 101 | ; Nothing
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| 102 | ; Corrupts registers:
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| 103 | ; Nothing
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| 104 | ;--------------------------------------------------------------------
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| 105 | ALIGN JUMP_ALIGN
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| 106 | DriveXlate_SetDriveToSwap:
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| 107 | test dl, dl ; Floppy drive?
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| 108 | js SHORT .SetHardDiskToSwap
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| 109 | .SetFloppyDriveToSwap:
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| 110 | mov [RAMVARS.xlateVars+XLATEVARS.bFDSwap], dl
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| 111 | ret
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| 112 | ALIGN JUMP_ALIGN
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| 113 | .SetHardDiskToSwap:
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| 114 | mov [RAMVARS.xlateVars+XLATEVARS.bHDSwap], dl
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| 115 | ret
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