| 1 | ; Project name : XTIDE Universal BIOS
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| 2 | ; Description : Functions for accessings RAMVARS.
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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 | ; Initializes RAMVARS.
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| 9 | ; Drive detection can be started after this function returns.
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| 10 | ;
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| 11 | ; RamVars_Initialize
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| 12 | ; Parameters:
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| 13 | ; Nothing
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| 14 | ; Returns:
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| 15 | ; DS: RAMVARS segment
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| 16 | ; Corrupts registers:
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| 17 | ; AX, CX, DI
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| 18 | ;--------------------------------------------------------------------
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| 19 | RamVars_Initialize:
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| 20 | push es
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| 21 | ; Fall to .StealMemoryForRAMVARS
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| 22 |
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| 23 | ;--------------------------------------------------------------------
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| 24 | ; .StealMemoryForRAMVARS
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| 25 | ; Parameters:
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| 26 | ; Nothing
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| 27 | ; Returns:
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| 28 | ; DS: RAMVARS segment
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| 29 | ; Corrupts registers:
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| 30 | ; AX
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| 31 | ;--------------------------------------------------------------------
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| 32 | .StealMemoryForRAMVARS:
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| 33 | test BYTE [cs:ROMVARS.wFlags], FLG_ROMVARS_FULLMODE
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| 34 | jz SHORT .InitializeRamvars ; No need to steal RAM
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| 35 |
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| 36 | LOAD_BDA_SEGMENT_TO ds, ax ; Zero AX
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| 37 | mov al, [cs:ROMVARS.bStealSize]
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| 38 | sub [BDA.wBaseMem], ax
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| 39 | mov ax, [BDA.wBaseMem]
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| 40 | eSHL_IM ax, 6 ; Segment to first stolen kB (*=40h)
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| 41 | mov ds, ax
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| 42 | mov WORD [FULLRAMVARS.wSign], W_SIGN_FULLRAMVARS
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| 43 | ; Fall to .InitializeRamvarsFromDS
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| 44 |
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| 45 | ;--------------------------------------------------------------------
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| 46 | ; .InitializeRamvars
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| 47 | ; Parameters:
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| 48 | ; Nothing
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| 49 | ; Returns:
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| 50 | ; DS: RAMVARS segment
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| 51 | ; Corrupts registers:
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| 52 | ; AX, CX, DI, ES
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| 53 | ;--------------------------------------------------------------------
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| 54 | .InitializeRamvars:
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| 55 | call RamVars_GetSegmentToDS
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| 56 | mov cx, RAMVARS_size
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| 57 | xor di, di
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| 58 | push ds
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| 59 | pop es
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| 60 | call Memory_ZeroESDIwithSizeInCX
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| 61 | ; Fall to .InitializeDriveTranslationAndReturn
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| 62 |
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| 63 | ;--------------------------------------------------------------------
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| 64 | ; .InitializeDriveTranslationAndReturn
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| 65 | ; Parameters:
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| 66 | ; DS: RAMVARS segment
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| 67 | ; Returns:
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| 68 | ; Nothing
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| 69 | ; Corrupts registers:
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| 70 | ; AX
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| 71 | ;--------------------------------------------------------------------
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| 72 | .InitializeDriveTranslationAndReturn:
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| 73 | pop es
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| 74 | jmp DriveXlate_Reset
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| 75 |
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| 76 |
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| 77 | ;--------------------------------------------------------------------
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| 78 | ; Returns segment to RAMVARS.
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| 79 | ; RAMVARS might be located at the top of interrupt vectors (0030:0000h)
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| 80 | ; or at the top of system base RAM.
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| 81 | ;
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| 82 | ; RamVars_GetSegmentToDS
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| 83 | ; Parameters:
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| 84 | ; Nothing
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| 85 | ; Returns:
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| 86 | ; DS: RAMVARS segment
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| 87 | ; Corrupts registers:
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| 88 | ; DI
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| 89 | ;--------------------------------------------------------------------
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| 90 | ALIGN JUMP_ALIGN
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| 91 | RamVars_GetSegmentToDS:
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| 92 | test BYTE [cs:ROMVARS.wFlags], FLG_ROMVARS_FULLMODE
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| 93 | jnz SHORT .GetStolenSegmentToDS
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| 94 | mov di, SEGMENT_RAMVARS_TOP_OF_INTERRUPT_VECTORS
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| 95 | mov ds, di
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| 96 | ret
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| 97 |
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| 98 | ALIGN JUMP_ALIGN
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| 99 | .GetStolenSegmentToDS:
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| 100 | LOAD_BDA_SEGMENT_TO ds, di
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| 101 | mov di, [BDA.wBaseMem] ; Load available base memory size in kB
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| 102 | eSHL_IM di, 6 ; Segment to first stolen kB (*=40h)
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| 103 | ALIGN JUMP_ALIGN
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| 104 | .LoopStolenKBs:
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| 105 | mov ds, di ; EBDA segment to DS
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| 106 | add di, BYTE 64 ; DI to next stolen kB
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| 107 | cmp WORD [FULLRAMVARS.wSign], W_SIGN_FULLRAMVARS
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| 108 | jne SHORT .LoopStolenKBs ; Loop until sign found (always found eventually)
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| 109 | ret
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| 110 |
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| 111 |
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| 112 | ;--------------------------------------------------------------------
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| 113 | ; Checks if INT 13h function is handled by this BIOS.
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| 114 | ;
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| 115 | ; RamVars_IsFunctionHandledByThisBIOS
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| 116 | ; Parameters:
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| 117 | ; AH: INT 13h function number
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| 118 | ; DL: Drive number
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| 119 | ; DS: RAMVARS segment
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| 120 | ; Returns:
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| 121 | ; CF: Set if function is handled by this BIOS
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| 122 | ; Cleared if function belongs to some other BIOS
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| 123 | ; Corrupts registers:
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| 124 | ; DI
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| 125 | ;--------------------------------------------------------------------
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| 126 | ALIGN JUMP_ALIGN
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| 127 | RamVars_IsFunctionHandledByThisBIOS:
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| 128 | test ah, ah ; Reset for all floppy and hard disk drives?
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| 129 | jz SHORT .FunctionIsHandledByOurBIOS
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| 130 | cmp ah, 08h ; Read Disk Drive Parameters?
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| 131 | jne SHORT RamVars_IsDriveHandledByThisBIOS
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| 132 | test dl, 80h ; We dot not handle floppy drives
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| 133 | jz SHORT .FunctionIsNotHandledByOurBIOS
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| 134 | ALIGN JUMP_ALIGN
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| 135 | .FunctionIsHandledByOurBIOS:
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| 136 | stc
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| 137 | .FunctionIsNotHandledByOurBIOS:
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| 138 | ret
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| 139 |
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| 140 | ;--------------------------------------------------------------------
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| 141 | ; Checks if drive is handled by this BIOS.
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| 142 | ;
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| 143 | ; RamVars_IsDriveHandledByThisBIOS
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| 144 | ; Parameters:
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| 145 | ; DL: Drive number
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| 146 | ; DS: RAMVARS segment
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| 147 | ; Returns:
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| 148 | ; CF: Set if drive is handled by this BIOS
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| 149 | ; Cleared if drive belongs to some other BIOS
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| 150 | ; Corrupts registers:
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| 151 | ; DI
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| 152 | ;--------------------------------------------------------------------
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| 153 | ALIGN JUMP_ALIGN
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| 154 | RamVars_IsDriveHandledByThisBIOS:
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| 155 | xchg di, ax ; Backup AX
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| 156 | mov ax, [RAMVARS.wDrvCntAndFirst] ; Drive count to AL, First number to AH
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| 157 | add al, ah ; One past last drive to AL
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| 158 | cmp dl, al ; Above last supported?
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| 159 | jae SHORT .DriveNotHandledByThisBIOS
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| 160 | cmp dl, ah ; Below first supported?
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| 161 | jb SHORT .DriveNotHandledByThisBIOS
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| 162 | xchg ax, di
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| 163 | stc
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| 164 | ret
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| 165 | ALIGN JUMP_ALIGN
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| 166 | .DriveNotHandledByThisBIOS:
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| 167 | xchg ax, di
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| 168 | clc
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| 169 | ret
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| 170 |
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| 171 |
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| 172 | ;--------------------------------------------------------------------
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| 173 | ; RamVars_IncrementHardDiskCount
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| 174 | ; Parameters:
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| 175 | ; DL: Drive number for new drive
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| 176 | ; DS: RAMVARS segment
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| 177 | ; Returns:
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| 178 | ; Nothing
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| 179 | ; Corrupts registers:
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| 180 | ; Nothing
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| 181 | ;--------------------------------------------------------------------
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| 182 | RamVars_IncrementHardDiskCount:
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| 183 | inc BYTE [RAMVARS.bDrvCnt] ; Increment drive count to RAMVARS
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| 184 | cmp BYTE [RAMVARS.bFirstDrv], 0 ; First drive set?
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| 185 | ja SHORT .Return ; If so, return
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| 186 | mov [RAMVARS.bFirstDrv], dl ; Store first drive number
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| 187 | .Return:
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| 188 | ret
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| 189 |
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| 190 |
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| 191 | ;--------------------------------------------------------------------
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| 192 | ; RamVars_GetHardDiskCountFromBDAtoCX
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| 193 | ; Parameters:
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| 194 | ; DS: RAMVARS segment
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| 195 | ; Returns:
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| 196 | ; CX: Total hard disk count
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| 197 | ; Corrupts registers:
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| 198 | ; Nothing
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| 199 | ;--------------------------------------------------------------------
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| 200 | ALIGN JUMP_ALIGN
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| 201 | RamVars_GetHardDiskCountFromBDAtoCX:
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| 202 | push es
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| 203 | push dx
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| 204 |
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| 205 | LOAD_BDA_SEGMENT_TO es, cx ; Zero CX
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| 206 | call RamVars_GetCountOfKnownDrivesToDL
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| 207 | MAX_U dl, [es:BDA.bHDCount]
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| 208 | mov cl, dl
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| 209 |
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| 210 | pop dx
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| 211 | pop es
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| 212 | ret
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| 213 |
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| 214 | ;--------------------------------------------------------------------
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| 215 | ; RamVars_GetCountOfKnownDrivesToDL
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| 216 | ; Parameters:
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| 217 | ; DS: RAMVARS segment
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| 218 | ; Returns:
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| 219 | ; DL: Total hard disk count
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| 220 | ; Corrupts registers:
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| 221 | ; Nothing
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| 222 | ;--------------------------------------------------------------------
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| 223 | ALIGN JUMP_ALIGN
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| 224 | RamVars_GetCountOfKnownDrivesToDL:
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| 225 | mov dl, [RAMVARS.bFirstDrv] ; Number for our first drive
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| 226 | add dl, [RAMVARS.bDrvCnt] ; Our drives
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| 227 | and dl, 7Fh ; Clear HD bit for drive count
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| 228 | ret
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| 229 |
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| 230 |
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| 231 | ;--------------------------------------------------------------------
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| 232 | ; RamVars_GetIdeControllerCountToCX
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| 233 | ; Parameters:
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| 234 | ; Nothing
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| 235 | ; Returns:
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| 236 | ; CX: Number of IDE controllers to handle
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| 237 | ; Corrupts registers:
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| 238 | ; Nothing
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| 239 | ;--------------------------------------------------------------------
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| 240 | RamVars_GetIdeControllerCountToCX:
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| 241 | eMOVZX cx, BYTE [cs:ROMVARS.bIdeCnt]
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| 242 | ret
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