| 1 | ; File name : AccessDPT.asm |
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| 2 | ; Project name : IDE BIOS |
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| 3 | ; Created date : 16.3.2010 |
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| 4 | ; Last update : 26.4.2010 |
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| 5 | ; Author : Tomi Tilli |
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| 6 | ; Description : Functions for accessing DPT data. |
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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 | ; Returns L-CHS values from DPT. |
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| 13 | ; |
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| 14 | ; AccessDPT_GetLCHSfromPCHS |
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| 15 | ; Parameters: |
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| 16 | ; DS:DI: Ptr to Disk Parameter Table |
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| 17 | ; Returns: |
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| 18 | ; AX: Number of L-CHS sectors per track |
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| 19 | ; BX: Number of L-CHS cylinders |
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| 20 | ; DX: Number of L-CHS heads |
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| 21 | ; Corrupts registers: |
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| 22 | ; Nothing |
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| 23 | ;-------------------------------------------------------------------- |
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| 24 | ALIGN JUMP_ALIGN |
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| 25 | AccessDPT_GetLCHSfromPCHS: |
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| 26 | xchg ax, cx |
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| 27 | mov cl, [di+DPT.bShLtoP] ; Load shift count |
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| 28 | mov bx, [di+DPT.wPCyls] ; Load P-CHS cylinders |
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| 29 | shr bx, cl ; Shift to L-CHS cylinders |
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| 30 | xchg cx, ax |
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| 31 | mov dx, [di+DPT.wLHeads] ; Load L-CHS heads |
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| 32 | eMOVZX ax, BYTE [di+DPT.bPSect] ; Load Sectors per track |
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| 33 | ret |
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| 34 | |
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| 35 | |
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| 36 | ;-------------------------------------------------------------------- |
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| 37 | ; Tests IDEVARS flags for master or slave drive. |
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| 38 | ; |
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| 39 | ; AccessDPT_TestIdeVarsFlagsForMasterOrSlaveDrive |
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| 40 | ; Parameters: |
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| 41 | ; AX: Bitmask to test DRVPARAMS.wFlags |
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| 42 | ; DS:DI: Ptr to Disk Parameter Table |
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| 43 | ; Returns: |
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| 44 | ; ZF: Set if tested bit was zero |
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| 45 | ; Cleared if tested bit was non-zero |
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| 46 | ; CF: 0 |
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| 47 | ; Corrupts registers: |
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| 48 | ; BX |
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| 49 | ;-------------------------------------------------------------------- |
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| 50 | ALIGN JUMP_ALIGN |
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| 51 | AccessDPT_TestIdeVarsFlagsForMasterOrSlaveDrive: |
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| 52 | call AccessDPT_GetPointerToDRVPARAMStoCSBX |
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| 53 | test [cs:bx+DRVPARAMS.wFlags], ax |
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| 54 | ret |
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| 55 | |
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| 56 | ;-------------------------------------------------------------------- |
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| 57 | ; Returns pointer to DRVPARAMS for master or slave drive. |
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| 58 | ; |
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| 59 | ; AccessDPT_GetPointerToDRVPARAMStoCSBX |
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| 60 | ; Parameters: |
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| 61 | ; DS:DI: Ptr to Disk Parameter Table |
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| 62 | ; Returns: |
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| 63 | ; CS:BX: Ptr to DRVPARAMS |
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| 64 | ; Corrupts registers: |
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| 65 | ; Nothing |
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| 66 | ;-------------------------------------------------------------------- |
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| 67 | ALIGN JUMP_ALIGN |
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| 68 | AccessDPT_GetPointerToDRVPARAMStoCSBX: |
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| 69 | eMOVZX bx, [di+DPT.bIdeOff] ; CS:BX points to IDEVARS |
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| 70 | test BYTE [di+DPT.bDrvSel], FLG_IDE_DRVHD_DRV |
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| 71 | jnz SHORT .ReturnPointerToSlaveDRVPARAMS |
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| 72 | add bx, BYTE IDEVARS.drvParamsMaster |
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| 73 | ret |
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| 74 | ALIGN JUMP_ALIGN |
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| 75 | .ReturnPointerToSlaveDRVPARAMS: |
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| 76 | add bx, BYTE IDEVARS.drvParamsSlave |
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| 77 | ret |
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