[41] | 1 | ; Project name : Assembly Library |
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| 2 | ; Description : Functions for accessing drives. |
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| 3 | |
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[376] | 4 | ; |
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[526] | 5 | ; XTIDE Universal BIOS and Associated Tools |
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| 6 | ; Copyright (C) 2009-2010 by Tomi Tilli, 2011-2013 by XTIDE Universal BIOS Team. |
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[376] | 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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[526] | 12 | ; |
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[376] | 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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[526] | 16 | ; GNU General Public License for more details. |
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[376] | 17 | ; Visit http://www.gnu.org/licenses/old-licenses/gpl-2.0.html |
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| 18 | ; |
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[41] | 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 | ; Drive_GetNumberOfAvailableDrivesToAX |
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| 25 | ; Parameters: |
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| 26 | ; Nothing |
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| 27 | ; Returns: |
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| 28 | ; AX: Number of available drives |
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| 29 | ; Corrupts registers: |
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| 30 | ; Nothing |
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| 31 | ;-------------------------------------------------------------------- |
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[592] | 32 | %ifndef EXCLUDE_FROM_XTIDECFG |
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[41] | 33 | ALIGN JUMP_ALIGN |
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| 34 | Drive_GetNumberOfAvailableDrivesToAX: |
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| 35 | push dx |
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| 36 | push cx |
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| 37 | |
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| 38 | call Drive_GetFlagsForAvailableDrivesToDXAX |
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| 39 | call Bit_GetSetCountToCXfromDXAX |
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| 40 | xchg ax, cx |
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| 41 | |
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| 42 | pop cx |
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| 43 | pop dx |
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| 44 | ret |
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[592] | 45 | %endif |
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[41] | 46 | |
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| 47 | |
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| 48 | ;-------------------------------------------------------------------- |
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| 49 | ; Drive_GetFlagsForAvailableDrivesToDXAX |
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| 50 | ; Parameters: |
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| 51 | ; Nothing |
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| 52 | ; Returns: |
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| 53 | ; DX:AX: Flags containing valid drives (bit 0 = drive A, bit 1 = drive B ...) |
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| 54 | ; Corrupts registers: |
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| 55 | ; Nothing |
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| 56 | ;-------------------------------------------------------------------- |
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| 57 | ALIGN JUMP_ALIGN |
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| 58 | Drive_GetFlagsForAvailableDrivesToDXAX: |
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| 59 | push cx |
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| 60 | push bx |
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| 61 | mov dx, DosCritical_HandlerToIgnoreAllErrors |
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| 62 | call DosCritical_InstallNewHandlerFromCSDX |
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| 63 | |
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| 64 | call .GetNumberOfPotentiallyValidDriveLettersToCX |
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| 65 | xor bx, bx |
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| 66 | xor ax, ax ; Temporary use BX:AX for flags |
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[133] | 67 | cwd ; Start from drive 0 |
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[41] | 68 | call .CheckDriveValidityUntilCXisZero |
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| 69 | mov dx, bx ; Flags now in DX:AX |
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| 70 | |
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| 71 | call DosCritical_RestoreDosHandler |
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| 72 | pop bx |
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| 73 | pop cx |
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| 74 | ret |
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| 75 | |
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| 76 | ;-------------------------------------------------------------------- |
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| 77 | ; .GetNumberOfPotentiallyValidDriveLettersToCX |
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| 78 | ; Parameters: |
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| 79 | ; Nothing |
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| 80 | ; Returns: |
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| 81 | ; CX: Number of potentially valid drive letters available |
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| 82 | ; Corrupts registers: |
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| 83 | ; AX, DX |
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| 84 | ;-------------------------------------------------------------------- |
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| 85 | ALIGN JUMP_ALIGN |
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| 86 | .GetNumberOfPotentiallyValidDriveLettersToCX: |
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| 87 | call Drive_GetDefaultToAL |
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| 88 | xchg dx, ax ; Default drive to DL |
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| 89 | call Drive_SetDefaultFromDL |
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[589] | 90 | cmp al, 32 ; Number of potentially valid drive letters available |
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| 91 | jb SHORT .Below32 |
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| 92 | mov al, 32 |
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| 93 | .Below32: |
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| 94 | cbw |
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| 95 | xchg cx, ax |
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[41] | 96 | ret |
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| 97 | |
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| 98 | ;-------------------------------------------------------------------- |
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| 99 | ; .CheckDriveValidityUntilCXisZero |
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| 100 | ; Parameters: |
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| 101 | ; CX: Number of potentially valid drive letters left |
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| 102 | ; DL: Drive number (00h=A:, 01h=B: ...) |
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| 103 | ; BX:AX: Flags for drive numbers |
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| 104 | ; Returns: |
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| 105 | ; BX:AX: Flags for valid drive numbers |
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| 106 | ; Corrupts registers: |
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| 107 | ; CX, DX |
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| 108 | ;-------------------------------------------------------------------- |
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| 109 | ALIGN JUMP_ALIGN |
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| 110 | .CheckDriveValidityUntilCXisZero: |
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| 111 | call .IsValidDriveNumberInDL |
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| 112 | jnz SHORT .PrepareToCheckNextDrive |
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| 113 | call .SetFlagToBXAXfromDriveInDL |
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| 114 | ALIGN JUMP_ALIGN |
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| 115 | .PrepareToCheckNextDrive: |
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| 116 | inc dx |
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| 117 | loop .CheckDriveValidityUntilCXisZero |
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| 118 | ret |
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| 119 | |
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| 120 | ;-------------------------------------------------------------------- |
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| 121 | ; .IsValidDriveNumberInDL |
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| 122 | ; Parameters: |
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| 123 | ; DL: Drive number (00h=A:, 01h=B: ...) |
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| 124 | ; Returns: |
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| 125 | ; ZF: Set if drive number is valid |
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| 126 | ; Cleared if drive number is invalid |
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| 127 | ; Corrupts registers: |
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| 128 | ; Nothing |
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| 129 | ;-------------------------------------------------------------------- |
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| 130 | ALIGN JUMP_ALIGN |
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| 131 | .IsValidDriveNumberInDL: |
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| 132 | push ds |
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| 133 | push ax |
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[593] | 134 | cmp dl, 1 |
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| 135 | jbe SHORT .FloppyDrive |
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[41] | 136 | |
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[593] | 137 | .MessageSuppressedByInt2FhHandler: |
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| 138 | .MoreThanOneFloppyDrive: |
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| 139 | .NoFloppyDrive: |
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| 140 | push bx |
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| 141 | |
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[41] | 142 | inc dx ; Default drive is 00h and first drive is 01h |
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[589] | 143 | mov ax, CHECK_IF_BLOCK_DEVICE_REMOTE ; Needs DOS 3.1+ |
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| 144 | mov bx, dx |
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| 145 | push dx |
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| 146 | int DOS_INTERRUPT_21h |
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| 147 | pop dx |
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| 148 | jnc SHORT .DriveIsValid |
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| 149 | cmp ax, ERR_DOS_INVALID_DRIVE |
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| 150 | je SHORT .DriveIsNotValid |
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| 151 | ; Fall back to old method if ERR_DOS_FUNCTION_NUMBER_INVALID |
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| 152 | |
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[41] | 153 | mov ah, GET_DOS_DRIVE_PARAMETER_BLOCK_FOR_SPECIFIC_DRIVE |
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| 154 | int DOS_INTERRUPT_21h |
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[589] | 155 | .DriveIsValid: |
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| 156 | .DriveIsNotValid: |
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[41] | 157 | dec dx |
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| 158 | test al, al |
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| 159 | |
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[593] | 160 | pop bx |
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| 161 | .ReturnFromFloppyDriveFiltering: |
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[41] | 162 | pop ax |
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| 163 | pop ds |
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| 164 | ret |
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| 165 | |
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[593] | 166 | .FloppyDrive: |
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| 167 | ; On single-floppy-drive systems, both A: and B: will point to the same physical drive. The problem is that DOS will print a message telling the user |
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| 168 | ; to "insert a disk and press any key to continue" when swapping from one logical drive to the other. To avoid this mess we hook interrupt 2Fh/AX=4A00h |
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| 169 | ; to signal to DOS that we will handle this ourselves. However, this only works on DOS 5+ so on older DOS versions we instead try to filter out |
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| 170 | ; the "other" logical drive (the one that isn't the current drive) during drive enumeration so the user can't select the "phantom" drive to begin with. |
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| 171 | ; This will have the somewhat strange effect of having a drive B: but no drive A: if B: happens to be the current logical floppy drive. |
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| 172 | |
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| 173 | cmp BYTE [bDosVersionMajor], 5 ; bDosVersionMajor must be provided by the application as it's not part of the library |
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| 174 | jae SHORT .MessageSuppressedByInt2FhHandler |
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| 175 | LOAD_BDA_SEGMENT_TO ds, ax |
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| 176 | mov al, [BDA.wEquipment] |
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| 177 | test al, 0C0h |
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| 178 | jnz SHORT .MoreThanOneFloppyDrive ; No phantom drive so no need for any filtering |
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| 179 | test al, 1 ; Any floppy drive at all? |
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| 180 | jz SHORT .NoFloppyDrive ; A pre-DOS 5 machine with no FDD is indeed a strange beast. However, don't trust the BIOS - let DOS decide |
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| 181 | cmp dl, [504h] ; MS-DOS - LOGICAL DRIVE FOR SINGLE-FLOPPY SYSTEM (A: / B:) |
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| 182 | jmp SHORT .ReturnFromFloppyDriveFiltering |
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| 183 | |
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[41] | 184 | ;-------------------------------------------------------------------- |
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| 185 | ; .SetFlagToBXAXfromDriveInDL |
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| 186 | ; Parameters: |
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| 187 | ; DL: Drive number (0...31) |
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| 188 | ; BX:AX: Flags containing drive numbers |
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| 189 | ; Returns: |
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| 190 | ; BX:AX: Flags with wanted drive bit set |
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| 191 | ; Corrupts registers: |
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| 192 | ; Nothing |
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| 193 | ;-------------------------------------------------------------------- |
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| 194 | ALIGN JUMP_ALIGN |
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| 195 | .SetFlagToBXAXfromDriveInDL: |
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| 196 | push cx |
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| 197 | |
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| 198 | mov cl, dl |
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| 199 | xchg dx, bx |
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| 200 | call Bit_SetToDXAXfromIndexInCL |
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| 201 | xchg bx, dx |
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| 202 | |
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| 203 | pop cx |
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| 204 | ret |
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| 205 | |
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| 206 | |
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| 207 | ;-------------------------------------------------------------------- |
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| 208 | ; Drive_GetDefaultToAL |
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| 209 | ; Parameters: |
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| 210 | ; Nothing |
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| 211 | ; Returns: |
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| 212 | ; AL: Current default drive (00h=A:, 01h=B: ...) |
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| 213 | ; Corrupts registers: |
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| 214 | ; AH |
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| 215 | ;-------------------------------------------------------------------- |
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| 216 | ALIGN JUMP_ALIGN |
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| 217 | Drive_GetDefaultToAL: |
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| 218 | mov ah, GET_CURRENT_DEFAULT_DRIVE |
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[133] | 219 | SKIP2B f ; cmp ax, <next instruction> |
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| 220 | ; Fall to Drive_SetDefaultFromDL |
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[41] | 221 | |
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| 222 | |
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| 223 | ;-------------------------------------------------------------------- |
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| 224 | ; Drive_SetDefaultFromDL |
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| 225 | ; Parameters: |
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| 226 | ; DL: New default drive (00h=A:, 01h=B: ...) |
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| 227 | ; Returns: |
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| 228 | ; AL: Number of potentially valid drive letters available |
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| 229 | ; Corrupts registers: |
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| 230 | ; AH |
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| 231 | ;-------------------------------------------------------------------- |
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| 232 | Drive_SetDefaultFromDL: |
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| 233 | mov ah, SELECT_DEFAULT_DRIVE |
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| 234 | int DOS_INTERRUPT_21h |
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| 235 | ret |
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