[3] | 1 | ; File name : RamVars.asm |
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| 2 | ; Project name : IDE BIOS |
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| 3 | ; Created date : 14.3.2010 |
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| 4 | ; Last update : 2.5.2010 |
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| 5 | ; Author : Tomi Tilli |
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| 6 | ; Description : Functions for accessings RAMVARS. |
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| 7 | |
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| 8 | ; Section containing code |
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| 9 | SECTION .text |
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| 10 | |
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| 11 | ;-------------------------------------------------------------------- |
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| 12 | ; Initializes RAMVARS. |
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| 13 | ; Drive detection can be started after this function returns. |
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| 14 | ; |
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| 15 | ; RamVars_Initialize |
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| 16 | ; Parameters: |
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| 17 | ; Nothing |
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| 18 | ; Returns: |
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| 19 | ; Nothing |
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| 20 | ; Corrupts registers: |
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| 21 | ; AX, CX, DI, DS, ES |
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| 22 | ;-------------------------------------------------------------------- |
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| 23 | ALIGN JUMP_ALIGN |
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| 24 | RamVars_Initialize: |
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| 25 | call RamVars_StealBaseMemory ; Get RAMVARS segment to DS even if no stealing |
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| 26 | call RamVars_ClearToZero |
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| 27 | jmp DriveXlate_Reset |
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| 28 | |
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| 29 | |
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| 30 | ;-------------------------------------------------------------------- |
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| 31 | ; Steals base memory to be used for RAMVARS. |
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| 32 | ; |
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| 33 | ; RamVars_StealBaseMemory |
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| 34 | ; Parameters: |
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| 35 | ; Nothing |
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| 36 | ; Returns: |
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| 37 | ; DS: RAMVARS segment |
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| 38 | ; Corrupts registers: |
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| 39 | ; AX |
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| 40 | ;-------------------------------------------------------------------- |
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| 41 | ALIGN JUMP_ALIGN |
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| 42 | RamVars_StealBaseMemory: |
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| 43 | test BYTE [cs:ROMVARS.wFlags], FLG_ROMVARS_FULLMODE |
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| 44 | jz SHORT RamVars_GetSegmentToDS ; No need to steal |
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| 45 | |
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| 46 | LOAD_BDA_SEGMENT_TO ds, ax ; Zero AX |
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| 47 | mov al, [cs:ROMVARS.bStealSize] |
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| 48 | sub [BDA.wBaseMem], ax ; Steal one or more kilobytes |
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| 49 | mov ax, [BDA.wBaseMem] ; Load base memory left |
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| 50 | eSHL_IM ax, 6 ; Shift for segment address |
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| 51 | mov ds, ax ; Copy RAMVARS segment to DS |
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| 52 | ret |
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| 53 | |
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| 54 | |
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| 55 | ;-------------------------------------------------------------------- |
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| 56 | ; Returns segment to RAMVARS. |
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| 57 | ; RAMVARS might be located at the top of interrupt vectors (0030:0000h) |
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| 58 | ; or at the top of system base RAM. |
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| 59 | ; |
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| 60 | ; RamVars_GetSegmentToDS |
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| 61 | ; Parameters: |
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| 62 | ; Nothing |
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| 63 | ; Returns: |
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| 64 | ; DS: RAMVARS segment |
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| 65 | ; Corrupts registers: |
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| 66 | ; DI |
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| 67 | ;-------------------------------------------------------------------- |
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| 68 | ALIGN JUMP_ALIGN |
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| 69 | RamVars_GetSegmentToDS: |
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| 70 | test BYTE [cs:ROMVARS.wFlags], FLG_ROMVARS_FULLMODE |
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| 71 | jnz SHORT RamVars_GetStolenSegmentToDS |
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| 72 | mov di, SEGMENT_RAMVARS_TOP_OF_INTERRUPT_VECTORS |
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| 73 | mov ds, di |
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| 74 | ret |
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| 75 | |
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| 76 | ALIGN JUMP_ALIGN |
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| 77 | RamVars_GetStolenSegmentToDS: |
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| 78 | LOAD_BDA_SEGMENT_TO ds, di |
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| 79 | mov di, [BDA.wBaseMem] ; Load available base memory size in kB |
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| 80 | eSHL_IM di, 6 ; Segment to first stolen kB |
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| 81 | ALIGN JUMP_ALIGN |
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| 82 | .LoopStolenKBs: |
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| 83 | mov ds, di ; EBDA segment to DS |
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| 84 | add di, BYTE 64 ; DI to next stolen kB |
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| 85 | cmp WORD [FULLRAMVARS.wSign], W_SIGN_FULLRAMVARS |
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| 86 | jne SHORT .LoopStolenKBs ; Loop until sign found (always found eventually) |
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| 87 | ret |
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| 88 | |
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| 89 | |
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| 90 | ;-------------------------------------------------------------------- |
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| 91 | ; Clears RAMVARS variables to zero. |
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| 92 | ; FULLRAMVARS sign will be saved if available. |
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| 93 | ; |
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| 94 | ; RamVars_ClearToZero |
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| 95 | ; Parameters: |
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| 96 | ; DS: RAMVARS segment |
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| 97 | ; Returns: |
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| 98 | ; Nothing |
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| 99 | ; Corrupts registers: |
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| 100 | ; AX, CX, DI, ES |
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| 101 | ;-------------------------------------------------------------------- |
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| 102 | ALIGN JUMP_ALIGN |
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| 103 | RamVars_ClearToZero: |
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| 104 | call FindDPT_PointToFirstDPT ; Get RAMVARS/FULLRAMVARS size to DI |
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| 105 | mov cx, di ; Copy byte count to CX |
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| 106 | push ds |
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| 107 | pop es |
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| 108 | xor di, di ; ES:DI now points to RAMVARS/FULLRAMVARS |
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| 109 | xor ax, ax ; Store zeroes |
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| 110 | rep stosb |
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| 111 | mov WORD [FULLRAMVARS.wSign], W_SIGN_FULLRAMVARS |
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| 112 | ret |
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| 113 | |
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| 114 | |
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| 115 | ;-------------------------------------------------------------------- |
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| 116 | ; Checks if INT 13h function is handled by this BIOS. |
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| 117 | ; |
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| 118 | ; RamVars_IsFunctionHandledByThisBIOS |
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| 119 | ; Parameters: |
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| 120 | ; AH: INT 13h function number |
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| 121 | ; DL: Drive number |
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| 122 | ; DS: RAMVARS segment |
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| 123 | ; Returns: |
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| 124 | ; CF: Set if function is handled by this BIOS |
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| 125 | ; Cleared if function belongs to some other BIOS |
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| 126 | ; Corrupts registers: |
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| 127 | ; DI |
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| 128 | ;-------------------------------------------------------------------- |
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| 129 | ALIGN JUMP_ALIGN |
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| 130 | RamVars_IsFunctionHandledByThisBIOS: |
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| 131 | test ah, ah ; Reset for all floppy and hard disk drives? |
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| 132 | jnz SHORT RamVars_IsDriveHandledByThisBIOS |
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| 133 | stc |
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| 134 | ret |
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| 135 | |
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| 136 | ;-------------------------------------------------------------------- |
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| 137 | ; Checks if drive is handled by this BIOS. |
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| 138 | ; |
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| 139 | ; RamVars_IsDriveHandledByThisBIOS |
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| 140 | ; Parameters: |
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| 141 | ; DL: Drive number |
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| 142 | ; DS: RAMVARS segment |
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| 143 | ; Returns: |
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| 144 | ; CF: Set if drive is handled by this BIOS |
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| 145 | ; Cleared if drive belongs to some other BIOS |
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| 146 | ; Corrupts registers: |
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| 147 | ; DI |
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| 148 | ;-------------------------------------------------------------------- |
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| 149 | ALIGN JUMP_ALIGN |
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| 150 | RamVars_IsDriveHandledByThisBIOS: |
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| 151 | xchg di, ax ; Backup AX |
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| 152 | mov ax, [RAMVARS.wDrvCntAndFirst] ; Drive count to AL, First number to AH |
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| 153 | add al, ah ; One past last drive to AL |
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| 154 | cmp dl, al ; Above last supported? |
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| 155 | jae SHORT .DriveNotHandledByThisBIOS |
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| 156 | cmp dl, ah ; Below first supported? |
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| 157 | jb SHORT .DriveNotHandledByThisBIOS |
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| 158 | xchg ax, di |
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| 159 | stc |
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| 160 | ret |
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| 161 | ALIGN JUMP_ALIGN |
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| 162 | .DriveNotHandledByThisBIOS: |
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| 163 | xchg ax, di |
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| 164 | clc |
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| 165 | ret |
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| 166 | |
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| 167 | |
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| 168 | ;-------------------------------------------------------------------- |
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| 169 | ; Increments hard disk count to RAMVARS. |
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| 170 | ; |
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| 171 | ; RamVars_IncrementHardDiskCount |
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| 172 | ; Parameters: |
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| 173 | ; DL: Drive number for new drive |
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| 174 | ; DS: RAMVARS segment |
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| 175 | ; Returns: |
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| 176 | ; Nothing |
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| 177 | ; Corrupts registers: |
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| 178 | ; Nothing |
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| 179 | ;-------------------------------------------------------------------- |
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| 180 | ALIGN JUMP_ALIGN |
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| 181 | RamVars_IncrementHardDiskCount: |
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| 182 | inc BYTE [RAMVARS.bDrvCnt] ; Increment drive count to RAMVARS |
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| 183 | cmp BYTE [RAMVARS.bFirstDrv], 0 ; First drive set? |
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| 184 | ja SHORT .Return ; If so, return |
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| 185 | mov [RAMVARS.bFirstDrv], dl ; Store first drive number |
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| 186 | ALIGN JUMP_ALIGN |
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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 | ; Return number of Hard Disks in system. |
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| 193 | ; |
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| 194 | ; RamVars_GetDriveCounts |
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| 195 | ; Parameters: |
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| 196 | ; DS: RAMVARS segment |
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| 197 | ; Returns: |
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| 198 | ; AL: Number of hard disks handled by our BIOS |
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| 199 | ; CX: Total number of hard disks in system |
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| 200 | ; Corrupts registers: |
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| 201 | ; AH |
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| 202 | ;-------------------------------------------------------------------- |
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| 203 | ALIGN JUMP_ALIGN |
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| 204 | RamVars_GetDriveCounts: |
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| 205 | push es |
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| 206 | LOAD_BDA_SEGMENT_TO es, cx ; Zero CX |
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| 207 | mov cl, [es:BDA.bHDCount] ; Total hard drive count |
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| 208 | mov al, [RAMVARS.bDrvCnt] ; Our drive count |
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| 209 | pop es |
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| 210 | ret |
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