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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