[150] | 1 | ; Project name : XTIDE Universal BIOS |
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[3] | 2 | ; Description : Functions for finding Disk Parameter Table. |
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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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[262] | 8 | ; Checks if drive is handled by this BIOS, and return DPT pointer. |
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[3] | 9 | ; |
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[262] | 10 | ; FindDPT_ForDriveNumberInDL |
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[3] | 11 | ; Parameters: |
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[262] | 12 | ; DL: Drive number |
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[3] | 13 | ; DS: RAMVARS segment |
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| 14 | ; Returns: |
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[262] | 15 | ; CF: Cleared if drive is handled by this BIOS |
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| 16 | ; Set if drive belongs to some other BIOS |
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| 17 | ; DI: DPT Pointer if drive is handled by this BIOS |
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| 18 | ; Zero if drive belongs to some other BIOS |
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[3] | 19 | ; Corrupts registers: |
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[262] | 20 | ; Nothing |
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[150] | 21 | ;-------------------------------------------------------------------- |
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| 22 | ALIGN JUMP_ALIGN |
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[262] | 23 | FindDPT_ForDriveNumberInDL: |
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| 24 | xchg di, ax ; Save the contents of AX in DI |
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| 25 | |
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| 26 | ; |
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| 27 | ; Check Our Hard Disks |
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| 28 | ; |
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| 29 | mov ax, [RAMVARS.wDrvCntAndFirst] ; Drive count to AH, First number to AL |
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| 30 | add ah, al ; One past last drive to AH |
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| 31 | |
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[258] | 32 | %ifdef MODULE_SERIAL_FLOPPY |
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[262] | 33 | cmp dl, ah ; Above last supported? |
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| 34 | jae SHORT .HardDiskNotHandledByThisBIOS |
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| 35 | |
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| 36 | cmp dl, al ; Below first supported? |
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| 37 | jae SHORT .CalcDPTForDriveNumber |
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| 38 | |
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| 39 | ALIGN JUMP_ALIGN |
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| 40 | .HardDiskNotHandledByThisBIOS: |
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| 41 | ; |
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| 42 | ; Check Our Floppy Disks |
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| 43 | ; |
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| 44 | call RamVars_UnpackFlopCntAndFirstToAL |
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| 45 | cbw ; normally 0h, could be ffh if no drives present |
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| 46 | adc ah, al ; if no drives present, still ffh (ffh + ffh + 1 = ffh) |
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| 47 | js SHORT .DiskIsNotHandledByThisBIOS |
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| 48 | cmp ah, dl ; Check second drive if two, first drive if only one |
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| 49 | jz SHORT .CalcDPTForDriveNumber |
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| 50 | cmp al, dl ; Check first drive in all cases, redundant but OK to repeat |
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| 51 | jnz SHORT .DiskIsNotHandledByThisBIOS |
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| 52 | %else |
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| 53 | cmp dl, ah ; Above last supported? |
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| 54 | jae SHORT .DiskIsNotHandledByThisBIOS |
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| 55 | |
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| 56 | cmp dl, al ; Below first supported? |
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| 57 | jb SHORT .DiskIsNotHandledByThisBIOS |
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[258] | 58 | %endif |
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[262] | 59 | ; fall-through to CalcDPTForDriveNumber |
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[150] | 60 | |
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| 61 | ;-------------------------------------------------------------------- |
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| 62 | ; Finds Disk Parameter Table for drive number. |
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[262] | 63 | ; Note intended to be called except by FindDPT_ForDriveNumber |
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[150] | 64 | ; |
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[262] | 65 | ; CalcDPTForDriveNumber |
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[150] | 66 | ; Parameters: |
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| 67 | ; DL: Drive number |
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| 68 | ; DS: RAMVARS segment |
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[262] | 69 | ; DI: Saved copy of AX from entry at FindDPT_ForDriveNumber |
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[150] | 70 | ; Returns: |
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| 71 | ; DS:DI: Ptr to DPT |
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[262] | 72 | ; CF: Clear |
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[150] | 73 | ; Corrupts registers: |
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[3] | 74 | ; Nothing |
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| 75 | ;-------------------------------------------------------------------- |
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| 76 | ALIGN JUMP_ALIGN |
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[262] | 77 | .CalcDPTForDriveNumber: |
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[150] | 78 | push dx |
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[3] | 79 | |
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[258] | 80 | %ifdef MODULE_SERIAL_FLOPPY |
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| 81 | mov ax, [RAMVARS.wDrvCntAndFirst] |
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| 82 | |
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| 83 | test dl, dl |
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| 84 | js .harddisk |
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| 85 | |
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| 86 | call RamVars_UnpackFlopCntAndFirstToAL |
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| 87 | add dl, ah ; add in end of hard disk DPT list, floppies start immediately after |
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[262] | 88 | |
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| 89 | ALIGN JUMP_ALIGN |
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[258] | 90 | .harddisk: |
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| 91 | sub dl, al ; subtract off beginning of either hard disk or floppy list (as appropriate) |
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| 92 | %else |
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| 93 | sub dl, [RAMVARS.bFirstDrv] ; subtract off beginning of hard disk list |
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| 94 | %endif |
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[262] | 95 | |
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| 96 | .CalcDPTForNewDrive: |
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[150] | 97 | mov al, LARGEST_DPT_SIZE |
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[258] | 98 | |
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[150] | 99 | mul dl |
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[262] | 100 | add ax, BYTE RAMVARS_size ; Clears CF (will not oveflow) |
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[3] | 101 | |
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[150] | 102 | pop dx |
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[262] | 103 | |
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| 104 | xchg di, ax ; Restore AX from entry at FindDPT_ForDriveNumber, put DPT pointer in DI |
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[150] | 105 | ret |
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| 106 | |
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[262] | 107 | ALIGN JUMP_ALIGN |
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| 108 | .DiskIsNotHandledByThisBIOS: |
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[259] | 109 | ; |
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[262] | 110 | ; Drive not found... |
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| 111 | ; |
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| 112 | xor ax, ax ; Clear DPT pointer |
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| 113 | stc ; Is not supported by our BIOS |
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| 114 | |
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| 115 | xchg di, ax ; Restore AX from save at top |
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[259] | 116 | ret |
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| 117 | |
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| 118 | ;-------------------------------------------------------------------- |
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[262] | 119 | ; Finds pointer to first unused Disk Parameter Table. |
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| 120 | ; Should only be used before DetectDrives is complete (not valid after this time). |
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[3] | 121 | ; |
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[262] | 122 | ; FindDPT_ForNewDriveToDSDI |
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[3] | 123 | ; Parameters: |
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| 124 | ; DS: RAMVARS segment |
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| 125 | ; Returns: |
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[262] | 126 | ; DS:DI: Ptr to first unused DPT |
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[3] | 127 | ; Corrupts registers: |
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[262] | 128 | ; AX |
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[3] | 129 | ;-------------------------------------------------------------------- |
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[262] | 130 | ALIGN JUMP_ALIGN |
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| 131 | FindDPT_ForNewDriveToDSDI: |
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| 132 | push dx |
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[200] | 133 | |
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[262] | 134 | %ifdef MODULE_SERIAL_FLOPPY |
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| 135 | mov dx, [RAMVARS.wDrvCntAndFlopCnt] |
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| 136 | add dl, dh |
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| 137 | %else |
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| 138 | mov dl, [RAMVARS.bDrvCnt] |
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| 139 | %endif |
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| 140 | |
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| 141 | jmp short FindDPT_ForDriveNumberInDL.CalcDPTForNewDrive |
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[3] | 142 | |
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[152] | 143 | ;-------------------------------------------------------------------- |
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[233] | 144 | ; IterateToDptWithFlagsHighInBL |
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[152] | 145 | ; Parameters: |
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| 146 | ; DS:DI: Ptr to DPT to examine |
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[233] | 147 | ; BL: Bit(s) to test in DPT.bFlagsHigh |
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[152] | 148 | ; Returns: |
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[262] | 149 | ; CF: Clear if wanted DPT found |
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| 150 | ; Set if wrong DPT |
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[152] | 151 | ; Corrupts registers: |
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| 152 | ; Nothing |
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| 153 | ;-------------------------------------------------------------------- |
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| 154 | ALIGN JUMP_ALIGN |
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[233] | 155 | IterateToDptWithFlagsHighInBL: |
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[262] | 156 | test BYTE [di+DPT.bFlagsHigh], bl ; Clears CF |
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| 157 | jnz SHORT .ReturnRightDPT |
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| 158 | stc |
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| 159 | .ReturnRightDPT: |
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[3] | 160 | ret |
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| 161 | |
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| 162 | ;-------------------------------------------------------------------- |
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[233] | 163 | ; FindDPT_ToDSDIforSerialDevice |
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[161] | 164 | ; Parameters: |
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| 165 | ; DS: RAMVARS segment |
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| 166 | ; Returns: |
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| 167 | ; DS:DI: Ptr to DPT |
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| 168 | ; CF: Set if wanted DPT found |
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| 169 | ; Cleared if DPT not found |
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| 170 | ; Corrupts registers: |
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[203] | 171 | ; SI |
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[161] | 172 | ;-------------------------------------------------------------------- |
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[265] | 173 | %ifdef MODULE_SERIAL |
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[233] | 174 | ALIGN JUMP_ALIGN |
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| 175 | FindDPT_ToDSDIforSerialDevice: |
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| 176 | mov bl, FLGH_DPT_SERIAL_DEVICE |
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| 177 | ; fall-through |
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[265] | 178 | %endif |
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[233] | 179 | |
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| 180 | ;-------------------------------------------------------------------- |
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| 181 | ; FindDPT_ToDSDIforFlagsHigh |
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| 182 | ; Parameters: |
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| 183 | ; DS: RAMVARS segment |
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| 184 | ; BL: Bit(s) to test in DPT.bFlagsHigh |
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| 185 | ; Returns: |
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| 186 | ; DS:DI: Ptr to DPT |
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| 187 | ; CF: Set if wanted DPT found |
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| 188 | ; Cleared if DPT not found |
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| 189 | ; Corrupts registers: |
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| 190 | ; SI |
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| 191 | ;-------------------------------------------------------------------- |
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[161] | 192 | ALIGN JUMP_ALIGN |
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[233] | 193 | FindDPT_ToDSDIforFlagsHighInBL: |
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| 194 | mov si, IterateToDptWithFlagsHighInBL |
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[161] | 195 | ; Fall to IterateAllDPTs |
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| 196 | |
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| 197 | ;-------------------------------------------------------------------- |
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[3] | 198 | ; Iterates all Disk Parameter Tables. |
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| 199 | ; |
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[150] | 200 | ; IterateAllDPTs |
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[3] | 201 | ; Parameters: |
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[152] | 202 | ; AX,BX,DX: Parameters to callback function |
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| 203 | ; CS:SI: Ptr to callback function |
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[262] | 204 | ; Callback routine should return CF=clear if found |
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[152] | 205 | ; DS: RAMVARS segment |
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[3] | 206 | ; Returns: |
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[152] | 207 | ; DS:DI: Ptr to wanted DPT (if found) |
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[258] | 208 | ; If not found, points to first empty DPT |
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[262] | 209 | ; CF: Clear if wanted DPT found |
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| 210 | ; Set if DPT not found, or no DPTs present |
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[3] | 211 | ; Corrupts registers: |
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[150] | 212 | ; Nothing unless corrupted by callback function |
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[3] | 213 | ;-------------------------------------------------------------------- |
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| 214 | ALIGN JUMP_ALIGN |
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[150] | 215 | IterateAllDPTs: |
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[3] | 216 | push cx |
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[258] | 217 | |
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| 218 | mov di, RAMVARS_size ; Point DS:DI to first DPT |
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| 219 | |
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[259] | 220 | mov cl, [RAMVARS.bDrvCnt] |
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| 221 | xor ch, ch ; Clears CF |
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[258] | 222 | |
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[262] | 223 | jcxz .NotFound ; Return if no drives |
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[259] | 224 | |
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[3] | 225 | ALIGN JUMP_ALIGN |
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| 226 | .LoopWhileDPTsLeft: |
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| 227 | call si ; Is wanted DPT? |
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[262] | 228 | jnc SHORT .Found ; If so, return |
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| 229 | add di, BYTE LARGEST_DPT_SIZE ; Point to next DPT |
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[258] | 230 | loop .LoopWhileDPTsLeft |
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[262] | 231 | |
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[3] | 232 | ALIGN JUMP_ALIGN |
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[262] | 233 | .NotFound: |
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| 234 | stc |
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| 235 | |
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| 236 | ALIGN JUMP_ALIGN |
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| 237 | .Found: |
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[3] | 238 | pop cx |
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| 239 | ret |
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[259] | 240 | |
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