[41] | 1 | ; Project name : Assembly Library |
---|
| 2 | ; Description : Functions for accessing drives. |
---|
| 3 | |
---|
[376] | 4 | ; |
---|
[526] | 5 | ; XTIDE Universal BIOS and Associated Tools |
---|
| 6 | ; Copyright (C) 2009-2010 by Tomi Tilli, 2011-2013 by XTIDE Universal BIOS Team. |
---|
[376] | 7 | ; |
---|
| 8 | ; This program is free software; you can redistribute it and/or modify |
---|
| 9 | ; it under the terms of the GNU General Public License as published by |
---|
| 10 | ; the Free Software Foundation; either version 2 of the License, or |
---|
| 11 | ; (at your option) any later version. |
---|
[526] | 12 | ; |
---|
[376] | 13 | ; This program is distributed in the hope that it will be useful, |
---|
| 14 | ; but WITHOUT ANY WARRANTY; without even the implied warranty of |
---|
| 15 | ; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
---|
[526] | 16 | ; GNU General Public License for more details. |
---|
[376] | 17 | ; Visit http://www.gnu.org/licenses/old-licenses/gpl-2.0.html |
---|
| 18 | ; |
---|
[41] | 19 | |
---|
| 20 | ; Section containing code |
---|
| 21 | SECTION .text |
---|
| 22 | |
---|
| 23 | ;-------------------------------------------------------------------- |
---|
| 24 | ; Drive_GetNumberOfAvailableDrivesToAX |
---|
| 25 | ; Parameters: |
---|
| 26 | ; Nothing |
---|
| 27 | ; Returns: |
---|
| 28 | ; AX: Number of available drives |
---|
| 29 | ; Corrupts registers: |
---|
| 30 | ; Nothing |
---|
| 31 | ;-------------------------------------------------------------------- |
---|
| 32 | ALIGN JUMP_ALIGN |
---|
| 33 | Drive_GetNumberOfAvailableDrivesToAX: |
---|
| 34 | push dx |
---|
| 35 | push cx |
---|
| 36 | |
---|
| 37 | call Drive_GetFlagsForAvailableDrivesToDXAX |
---|
| 38 | call Bit_GetSetCountToCXfromDXAX |
---|
| 39 | xchg ax, cx |
---|
| 40 | |
---|
| 41 | pop cx |
---|
| 42 | pop dx |
---|
| 43 | ret |
---|
| 44 | |
---|
| 45 | |
---|
| 46 | ;-------------------------------------------------------------------- |
---|
| 47 | ; Drive_GetFlagsForAvailableDrivesToDXAX |
---|
| 48 | ; Parameters: |
---|
| 49 | ; Nothing |
---|
| 50 | ; Returns: |
---|
| 51 | ; DX:AX: Flags containing valid drives (bit 0 = drive A, bit 1 = drive B ...) |
---|
| 52 | ; Corrupts registers: |
---|
| 53 | ; Nothing |
---|
| 54 | ;-------------------------------------------------------------------- |
---|
| 55 | ALIGN JUMP_ALIGN |
---|
| 56 | Drive_GetFlagsForAvailableDrivesToDXAX: |
---|
| 57 | push cx |
---|
| 58 | push bx |
---|
| 59 | mov dx, DosCritical_HandlerToIgnoreAllErrors |
---|
| 60 | call DosCritical_InstallNewHandlerFromCSDX |
---|
| 61 | |
---|
| 62 | call .GetNumberOfPotentiallyValidDriveLettersToCX |
---|
| 63 | xor bx, bx |
---|
| 64 | xor ax, ax ; Temporary use BX:AX for flags |
---|
[133] | 65 | cwd ; Start from drive 0 |
---|
[41] | 66 | call .CheckDriveValidityUntilCXisZero |
---|
| 67 | mov dx, bx ; Flags now in DX:AX |
---|
| 68 | |
---|
| 69 | call DosCritical_RestoreDosHandler |
---|
| 70 | pop bx |
---|
| 71 | pop cx |
---|
| 72 | ret |
---|
| 73 | |
---|
| 74 | ;-------------------------------------------------------------------- |
---|
| 75 | ; .GetNumberOfPotentiallyValidDriveLettersToCX |
---|
| 76 | ; Parameters: |
---|
| 77 | ; Nothing |
---|
| 78 | ; Returns: |
---|
| 79 | ; CX: Number of potentially valid drive letters available |
---|
| 80 | ; Corrupts registers: |
---|
| 81 | ; AX, DX |
---|
| 82 | ;-------------------------------------------------------------------- |
---|
| 83 | ALIGN JUMP_ALIGN |
---|
| 84 | .GetNumberOfPotentiallyValidDriveLettersToCX: |
---|
| 85 | call Drive_GetDefaultToAL |
---|
| 86 | xchg dx, ax ; Default drive to DL |
---|
| 87 | call Drive_SetDefaultFromDL |
---|
| 88 | eMOVZX cx, al ; Number of potentially valid drive letters available |
---|
[181] | 89 | cmp cl, 32 |
---|
| 90 | jb SHORT .Return |
---|
| 91 | mov cl, 32 |
---|
| 92 | ALIGN JUMP_ALIGN, ret |
---|
| 93 | .Return: |
---|
[41] | 94 | ret |
---|
| 95 | |
---|
| 96 | ;-------------------------------------------------------------------- |
---|
| 97 | ; .CheckDriveValidityUntilCXisZero |
---|
| 98 | ; Parameters: |
---|
| 99 | ; CX: Number of potentially valid drive letters left |
---|
| 100 | ; DL: Drive number (00h=A:, 01h=B: ...) |
---|
| 101 | ; BX:AX: Flags for drive numbers |
---|
| 102 | ; Returns: |
---|
| 103 | ; BX:AX: Flags for valid drive numbers |
---|
| 104 | ; Corrupts registers: |
---|
| 105 | ; CX, DX |
---|
| 106 | ;-------------------------------------------------------------------- |
---|
| 107 | ALIGN JUMP_ALIGN |
---|
| 108 | .CheckDriveValidityUntilCXisZero: |
---|
| 109 | call .IsValidDriveNumberInDL |
---|
| 110 | jnz SHORT .PrepareToCheckNextDrive |
---|
| 111 | call .SetFlagToBXAXfromDriveInDL |
---|
| 112 | ALIGN JUMP_ALIGN |
---|
| 113 | .PrepareToCheckNextDrive: |
---|
| 114 | inc dx |
---|
| 115 | loop .CheckDriveValidityUntilCXisZero |
---|
| 116 | ret |
---|
| 117 | |
---|
| 118 | ;-------------------------------------------------------------------- |
---|
| 119 | ; .IsValidDriveNumberInDL |
---|
| 120 | ; Parameters: |
---|
| 121 | ; DL: Drive number (00h=A:, 01h=B: ...) |
---|
| 122 | ; Returns: |
---|
| 123 | ; ZF: Set if drive number is valid |
---|
| 124 | ; Cleared if drive number is invalid |
---|
| 125 | ; Corrupts registers: |
---|
| 126 | ; Nothing |
---|
| 127 | ;-------------------------------------------------------------------- |
---|
| 128 | ALIGN JUMP_ALIGN |
---|
| 129 | .IsValidDriveNumberInDL: |
---|
| 130 | push ds |
---|
| 131 | push bx |
---|
| 132 | push ax |
---|
| 133 | |
---|
| 134 | inc dx ; Default drive is 00h and first drive is 01h |
---|
| 135 | mov ah, GET_DOS_DRIVE_PARAMETER_BLOCK_FOR_SPECIFIC_DRIVE |
---|
| 136 | int DOS_INTERRUPT_21h |
---|
| 137 | dec dx |
---|
| 138 | test al, al |
---|
| 139 | |
---|
| 140 | pop ax |
---|
| 141 | pop bx |
---|
| 142 | pop ds |
---|
| 143 | ret |
---|
| 144 | |
---|
| 145 | ;-------------------------------------------------------------------- |
---|
| 146 | ; .SetFlagToBXAXfromDriveInDL |
---|
| 147 | ; Parameters: |
---|
| 148 | ; DL: Drive number (0...31) |
---|
| 149 | ; BX:AX: Flags containing drive numbers |
---|
| 150 | ; Returns: |
---|
| 151 | ; BX:AX: Flags with wanted drive bit set |
---|
| 152 | ; Corrupts registers: |
---|
| 153 | ; Nothing |
---|
| 154 | ;-------------------------------------------------------------------- |
---|
| 155 | ALIGN JUMP_ALIGN |
---|
| 156 | .SetFlagToBXAXfromDriveInDL: |
---|
| 157 | push cx |
---|
| 158 | |
---|
| 159 | mov cl, dl |
---|
| 160 | xchg dx, bx |
---|
| 161 | call Bit_SetToDXAXfromIndexInCL |
---|
| 162 | xchg bx, dx |
---|
| 163 | |
---|
| 164 | pop cx |
---|
| 165 | ret |
---|
| 166 | |
---|
| 167 | |
---|
| 168 | ;-------------------------------------------------------------------- |
---|
| 169 | ; Drive_GetDefaultToAL |
---|
| 170 | ; Parameters: |
---|
| 171 | ; Nothing |
---|
| 172 | ; Returns: |
---|
| 173 | ; AL: Current default drive (00h=A:, 01h=B: ...) |
---|
| 174 | ; Corrupts registers: |
---|
| 175 | ; AH |
---|
| 176 | ;-------------------------------------------------------------------- |
---|
| 177 | ALIGN JUMP_ALIGN |
---|
| 178 | Drive_GetDefaultToAL: |
---|
| 179 | mov ah, GET_CURRENT_DEFAULT_DRIVE |
---|
[133] | 180 | SKIP2B f ; cmp ax, <next instruction> |
---|
| 181 | ; Fall to Drive_SetDefaultFromDL |
---|
[41] | 182 | |
---|
| 183 | |
---|
| 184 | ;-------------------------------------------------------------------- |
---|
| 185 | ; Drive_SetDefaultFromDL |
---|
| 186 | ; Parameters: |
---|
| 187 | ; DL: New default drive (00h=A:, 01h=B: ...) |
---|
| 188 | ; Returns: |
---|
| 189 | ; AL: Number of potentially valid drive letters available |
---|
| 190 | ; Corrupts registers: |
---|
| 191 | ; AH |
---|
| 192 | ;-------------------------------------------------------------------- |
---|
| 193 | Drive_SetDefaultFromDL: |
---|
| 194 | mov ah, SELECT_DEFAULT_DRIVE |
---|
| 195 | int DOS_INTERRUPT_21h |
---|
| 196 | ret |
---|