[90] | 1 | ; Project name : XTIDE Universal BIOS |
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[3] | 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 | ; Nothing |
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| 16 | ; Corrupts registers: |
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[90] | 17 | ; AX, CX, DI, DS |
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[3] | 18 | ;-------------------------------------------------------------------- |
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| 19 | ALIGN JUMP_ALIGN |
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| 20 | RamVars_Initialize: |
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[90] | 21 | push es |
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[33] | 22 | call .StealMemoryForRAMVARS ; Get RAMVARS segment to DS even if no stealing |
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| 23 | call .ClearRamvarsFromDS |
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[90] | 24 | pop es |
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[3] | 25 | jmp DriveXlate_Reset |
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| 26 | |
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| 27 | ;-------------------------------------------------------------------- |
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[33] | 28 | ; .StealMemoryForRAMVARS |
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[3] | 29 | ; Parameters: |
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| 30 | ; Nothing |
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| 31 | ; Returns: |
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| 32 | ; DS: RAMVARS segment |
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| 33 | ; Corrupts registers: |
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| 34 | ; AX |
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| 35 | ;-------------------------------------------------------------------- |
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| 36 | ALIGN JUMP_ALIGN |
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[33] | 37 | .StealMemoryForRAMVARS: |
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[3] | 38 | test BYTE [cs:ROMVARS.wFlags], FLG_ROMVARS_FULLMODE |
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[33] | 39 | jz SHORT RamVars_GetSegmentToDS |
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[3] | 40 | |
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[33] | 41 | LOAD_BDA_SEGMENT_TO ds, ax ; Zero AX |
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[3] | 42 | mov al, [cs:ROMVARS.bStealSize] |
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[33] | 43 | sub [BDA.wBaseMem], ax |
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| 44 | mov ax, [BDA.wBaseMem] |
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| 45 | eSHL_IM ax, 6 ; Segment to first stolen kB (*=40h) |
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| 46 | mov ds, ax |
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[3] | 47 | ret |
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| 48 | |
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[33] | 49 | ;-------------------------------------------------------------------- |
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| 50 | ; .ClearRamvarsFromDS |
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| 51 | ; Parameters: |
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| 52 | ; DS: RAMVARS segment |
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| 53 | ; Returns: |
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| 54 | ; Nothing |
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| 55 | ; Corrupts registers: |
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| 56 | ; AX, CX, DI, ES |
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| 57 | ;-------------------------------------------------------------------- |
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| 58 | ALIGN JUMP_ALIGN |
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| 59 | .ClearRamvarsFromDS: |
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| 60 | call FindDPT_PointToFirstDPT ; Get RAMVARS/FULLRAMVARS size to DI |
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| 61 | mov cx, di ; Copy byte count to CX |
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| 62 | push ds |
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| 63 | pop es |
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| 64 | xor di, di ; ES:DI now points to RAMVARS/FULLRAMVARS |
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| 65 | xor ax, ax ; Store zeroes |
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| 66 | rep stosb |
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| 67 | mov WORD [FULLRAMVARS.wSign], W_SIGN_FULLRAMVARS |
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| 68 | ret |
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[3] | 69 | |
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[33] | 70 | |
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[3] | 71 | ;-------------------------------------------------------------------- |
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| 72 | ; Returns segment to RAMVARS. |
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| 73 | ; RAMVARS might be located at the top of interrupt vectors (0030:0000h) |
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| 74 | ; or at the top of system base RAM. |
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| 75 | ; |
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| 76 | ; RamVars_GetSegmentToDS |
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| 77 | ; Parameters: |
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| 78 | ; Nothing |
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| 79 | ; Returns: |
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| 80 | ; DS: RAMVARS segment |
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| 81 | ; Corrupts registers: |
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| 82 | ; DI |
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| 83 | ;-------------------------------------------------------------------- |
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| 84 | ALIGN JUMP_ALIGN |
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| 85 | RamVars_GetSegmentToDS: |
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| 86 | test BYTE [cs:ROMVARS.wFlags], FLG_ROMVARS_FULLMODE |
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[33] | 87 | jnz SHORT .GetStolenSegmentToDS |
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[3] | 88 | mov di, SEGMENT_RAMVARS_TOP_OF_INTERRUPT_VECTORS |
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| 89 | mov ds, di |
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| 90 | ret |
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| 91 | |
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| 92 | ALIGN JUMP_ALIGN |
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[33] | 93 | .GetStolenSegmentToDS: |
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[3] | 94 | LOAD_BDA_SEGMENT_TO ds, di |
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| 95 | mov di, [BDA.wBaseMem] ; Load available base memory size in kB |
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[33] | 96 | eSHL_IM di, 6 ; Segment to first stolen kB (*=40h) |
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[3] | 97 | ALIGN JUMP_ALIGN |
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| 98 | .LoopStolenKBs: |
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| 99 | mov ds, di ; EBDA segment to DS |
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| 100 | add di, BYTE 64 ; DI to next stolen kB |
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| 101 | cmp WORD [FULLRAMVARS.wSign], W_SIGN_FULLRAMVARS |
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| 102 | jne SHORT .LoopStolenKBs ; Loop until sign found (always found eventually) |
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| 103 | ret |
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| 104 | |
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| 105 | |
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| 106 | ;-------------------------------------------------------------------- |
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| 107 | ; Checks if INT 13h function is handled by this BIOS. |
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| 108 | ; |
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| 109 | ; RamVars_IsFunctionHandledByThisBIOS |
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| 110 | ; Parameters: |
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| 111 | ; AH: INT 13h function number |
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| 112 | ; DL: Drive number |
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| 113 | ; DS: RAMVARS segment |
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| 114 | ; Returns: |
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| 115 | ; CF: Set if function is handled by this BIOS |
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| 116 | ; Cleared if function belongs to some other BIOS |
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| 117 | ; Corrupts registers: |
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| 118 | ; DI |
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| 119 | ;-------------------------------------------------------------------- |
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| 120 | ALIGN JUMP_ALIGN |
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| 121 | RamVars_IsFunctionHandledByThisBIOS: |
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| 122 | test ah, ah ; Reset for all floppy and hard disk drives? |
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[32] | 123 | jz SHORT .FunctionIsHandledByOurBIOS |
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| 124 | cmp ah, 08h ; Read Disk Drive Parameters? |
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| 125 | jne SHORT RamVars_IsDriveHandledByThisBIOS |
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| 126 | test dl, 80h ; We dot not handle floppy drives |
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| 127 | jz SHORT .FunctionIsNotHandledByOurBIOS |
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| 128 | ALIGN JUMP_ALIGN |
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| 129 | .FunctionIsHandledByOurBIOS: |
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[3] | 130 | stc |
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[32] | 131 | .FunctionIsNotHandledByOurBIOS: |
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[3] | 132 | ret |
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| 133 | |
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| 134 | ;-------------------------------------------------------------------- |
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| 135 | ; Checks if drive is handled by this BIOS. |
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| 136 | ; |
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| 137 | ; RamVars_IsDriveHandledByThisBIOS |
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| 138 | ; Parameters: |
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| 139 | ; DL: Drive number |
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| 140 | ; DS: RAMVARS segment |
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| 141 | ; Returns: |
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| 142 | ; CF: Set if drive is handled by this BIOS |
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| 143 | ; Cleared if drive belongs to some other BIOS |
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| 144 | ; Corrupts registers: |
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| 145 | ; DI |
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| 146 | ;-------------------------------------------------------------------- |
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| 147 | ALIGN JUMP_ALIGN |
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| 148 | RamVars_IsDriveHandledByThisBIOS: |
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| 149 | xchg di, ax ; Backup AX |
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| 150 | mov ax, [RAMVARS.wDrvCntAndFirst] ; Drive count to AL, First number to AH |
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| 151 | add al, ah ; One past last drive to AL |
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| 152 | cmp dl, al ; Above last supported? |
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| 153 | jae SHORT .DriveNotHandledByThisBIOS |
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| 154 | cmp dl, ah ; Below first supported? |
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| 155 | jb SHORT .DriveNotHandledByThisBIOS |
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| 156 | xchg ax, di |
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| 157 | stc |
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| 158 | ret |
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| 159 | ALIGN JUMP_ALIGN |
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| 160 | .DriveNotHandledByThisBIOS: |
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| 161 | xchg ax, di |
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| 162 | clc |
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| 163 | ret |
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| 164 | |
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| 165 | |
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| 166 | ;-------------------------------------------------------------------- |
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| 167 | ; Increments hard disk count to RAMVARS. |
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| 168 | ; |
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| 169 | ; RamVars_IncrementHardDiskCount |
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| 170 | ; Parameters: |
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| 171 | ; DL: Drive number for new drive |
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| 172 | ; DS: RAMVARS segment |
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| 173 | ; Returns: |
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| 174 | ; Nothing |
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| 175 | ; Corrupts registers: |
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| 176 | ; Nothing |
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| 177 | ;-------------------------------------------------------------------- |
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| 178 | ALIGN JUMP_ALIGN |
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| 179 | RamVars_IncrementHardDiskCount: |
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| 180 | inc BYTE [RAMVARS.bDrvCnt] ; Increment drive count to RAMVARS |
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| 181 | cmp BYTE [RAMVARS.bFirstDrv], 0 ; First drive set? |
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| 182 | ja SHORT .Return ; If so, return |
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| 183 | mov [RAMVARS.bFirstDrv], dl ; Store first drive number |
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| 184 | ALIGN JUMP_ALIGN |
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| 185 | .Return: |
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| 186 | ret |
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| 187 | |
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| 188 | |
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| 189 | ;-------------------------------------------------------------------- |
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[32] | 190 | ; RamVars_GetHardDiskCountFromBDAtoCX |
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[3] | 191 | ; Parameters: |
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| 192 | ; DS: RAMVARS segment |
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| 193 | ; Returns: |
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[32] | 194 | ; CX: Total hard disk count |
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[3] | 195 | ; Corrupts registers: |
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[32] | 196 | ; Nothing |
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| 197 | ;-------------------------------------------------------------------- |
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[3] | 198 | ALIGN JUMP_ALIGN |
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[32] | 199 | RamVars_GetHardDiskCountFromBDAtoCX: |
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[3] | 200 | push es |
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[32] | 201 | push dx |
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| 202 | |
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[3] | 203 | LOAD_BDA_SEGMENT_TO es, cx ; Zero CX |
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[32] | 204 | call RamVars_GetCountOfKnownDrivesToDL |
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| 205 | MAX_U dl, [es:BDA.bHDCount] |
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| 206 | mov cl, dl |
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| 207 | |
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| 208 | pop dx |
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[3] | 209 | pop es |
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| 210 | ret |
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[32] | 211 | |
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| 212 | ;-------------------------------------------------------------------- |
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| 213 | ; RamVars_GetCountOfKnownDrivesToDL |
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| 214 | ; Parameters: |
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| 215 | ; DS: RAMVARS segment |
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| 216 | ; Returns: |
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| 217 | ; DL: Total hard disk count |
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| 218 | ; Corrupts registers: |
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| 219 | ; Nothing |
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| 220 | ;-------------------------------------------------------------------- |
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| 221 | ALIGN JUMP_ALIGN |
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| 222 | RamVars_GetCountOfKnownDrivesToDL: |
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| 223 | mov dl, [RAMVARS.bFirstDrv] ; Number for our first drive |
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| 224 | add dl, [RAMVARS.bDrvCnt] ; Our drives |
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| 225 | and dl, 7Fh ; Clear HD bit for drive count |
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| 226 | ret |
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[33] | 227 | |
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| 228 | |
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| 229 | ;-------------------------------------------------------------------- |
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| 230 | ; RamVars_GetIdeControllerCountToCX |
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| 231 | ; Parameters: |
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| 232 | ; Nothing |
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| 233 | ; Returns: |
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| 234 | ; CX: Number of IDE controllers to handle |
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| 235 | ; Corrupts registers: |
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| 236 | ; Nothing |
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| 237 | ;-------------------------------------------------------------------- |
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| 238 | ALIGN JUMP_ALIGN |
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| 239 | RamVars_GetIdeControllerCountToCX: |
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| 240 | mov cx, 1 ; Assume lite mode (one controller) |
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| 241 | test BYTE [cs:ROMVARS.wFlags], FLG_ROMVARS_FULLMODE |
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| 242 | jz SHORT .Return |
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| 243 | mov cl, [cs:ROMVARS.bIdeCnt] |
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| 244 | ALIGN JUMP_ALIGN, ret |
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| 245 | .Return: |
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| 246 | ret |
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