[99] | 1 | ; Project name : XTIDE Universal BIOS |
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[3] | 2 | ; Description : Functions for accessing DPT data. |
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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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[150] | 8 | ; AccessDPT_GetDriveSelectByteToAL |
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| 9 | ; Parameters: |
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| 10 | ; DS:DI: Ptr to Disk Parameter Table |
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| 11 | ; Returns: |
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| 12 | ; AL: Drive Select Byte |
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| 13 | ; Corrupts registers: |
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| 14 | ; Nothing |
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| 15 | ;-------------------------------------------------------------------- |
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| 16 | ALIGN JUMP_ALIGN |
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| 17 | AccessDPT_GetDriveSelectByteToAL: |
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| 18 | mov al, [di+DPT.wFlags] |
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| 19 | and al, FLG_DRVNHEAD_LBA | FLG_DRVNHEAD_DRV |
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| 20 | or al, MASK_DRVNHEAD_SET ; Bits set to 1 for old drives |
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| 21 | ret |
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| 22 | |
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| 23 | |
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| 24 | ;-------------------------------------------------------------------- |
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| 25 | ; AccessDPT_GetDeviceControlByteToAL |
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| 26 | ; Parameters: |
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| 27 | ; DS:DI: Ptr to Disk Parameter Table |
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| 28 | ; Returns: |
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| 29 | ; AL: Device Control Byte |
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| 30 | ; Corrupts registers: |
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| 31 | ; Nothing |
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| 32 | ;-------------------------------------------------------------------- |
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| 33 | ALIGN JUMP_ALIGN |
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| 34 | AccessDPT_GetDeviceControlByteToAL: |
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| 35 | xor al, al |
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[158] | 36 | test BYTE [di+DPT.bFlagsLow], FLGL_DPT_ENABLE_IRQ |
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[150] | 37 | jnz SHORT .EnableDeviceIrq |
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| 38 | or al, FLG_DEVCONTROL_nIEN ; Disable IRQ |
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| 39 | .EnableDeviceIrq: |
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| 40 | ret |
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| 41 | |
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| 42 | |
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| 43 | ;-------------------------------------------------------------------- |
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| 44 | ; AccessDPT_GetAddressingModeForWordLookToBX |
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| 45 | ; Parameters: |
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| 46 | ; DS:DI: Ptr to Disk Parameter Table |
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| 47 | ; Returns: |
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| 48 | ; BX: Addressing Mode (L-CHS, P-CHS, LBA28, LBA48) shifted for WORD lookup |
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| 49 | ; Corrupts registers: |
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| 50 | ; Nothing |
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| 51 | ;-------------------------------------------------------------------- |
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| 52 | ALIGN JUMP_ALIGN |
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| 53 | AccessDPT_GetAddressingModeForWordLookToBX: |
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[158] | 54 | mov bl, [di+DPT.bFlagsLow] |
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| 55 | and bx, BYTE MASKL_DPT_ADDRESSING_MODE |
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[150] | 56 | eSHR_IM bx, ADDRESSING_MODE_FIELD_POSITION-1 |
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| 57 | ret |
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| 58 | |
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| 59 | |
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| 60 | ;-------------------------------------------------------------------- |
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[173] | 61 | ; AccessDPT_GetLCHS |
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[3] | 62 | ; Parameters: |
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| 63 | ; DS:DI: Ptr to Disk Parameter Table |
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| 64 | ; Returns: |
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| 65 | ; AX: Number of L-CHS sectors per track |
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| 66 | ; BX: Number of L-CHS cylinders |
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| 67 | ; DX: Number of L-CHS heads |
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| 68 | ; Corrupts registers: |
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[173] | 69 | ; CX |
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[3] | 70 | ;-------------------------------------------------------------------- |
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[173] | 71 | AccessDPT_GetLCHS: |
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| 72 | ; Load CHS from DPT |
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| 73 | eMOVZX ax, BYTE [di+DPT.bSectors] |
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| 74 | mov bx, [di+DPT.dwCylinders] |
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[161] | 75 | cwd |
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[173] | 76 | mov dl, [di+DPT.bHeads] |
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| 77 | |
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| 78 | ; Only need to limit sectors for LBA assist |
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| 79 | test BYTE [di+DPT.bFlagsLow], FLG_DRVNHEAD_LBA |
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| 80 | jnz SHORT .ReturnLbaAssistedLCHS |
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| 81 | |
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| 82 | ; P-CHS to L-CHS translation when necessary |
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| 83 | jmp SHORT AccessDPT_ShiftPCHinBXDXtoLCH |
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| 84 | |
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| 85 | .ReturnLbaAssistedLCHS: |
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| 86 | cmp WORD [di+DPT.dwCylinders+2], BYTE 0 |
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| 87 | jz SHORT .LimitCylindersTo1024 |
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| 88 | mov bx, MAX_LCHS_CYLINDERS |
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| 89 | .LimitCylindersTo1024: |
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| 90 | MIN_U bx, MAX_LCHS_CYLINDERS |
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[3] | 91 | ret |
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| 92 | |
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| 93 | |
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| 94 | ;-------------------------------------------------------------------- |
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[173] | 95 | ; AccessDPT_ShiftPCHinBXDXtoLCH |
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| 96 | ; Parameters: |
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| 97 | ; BX: P-CHS cylinders (1...16383) |
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| 98 | ; DX: P-CHS heads (1...16) |
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| 99 | ; Returns: |
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| 100 | ; BX: Number of L-CHS cylinders (1...1024) |
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| 101 | ; DX: Number of L-CHS heads (1...255) |
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| 102 | ; CX: Number of bits shifted |
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| 103 | ; Corrupts registers: |
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| 104 | ; Nothing |
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| 105 | ;-------------------------------------------------------------------- |
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| 106 | AccessDPT_ShiftPCHinBXDXtoLCH: |
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| 107 | xor cx, cx |
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| 108 | .ShiftLoop: |
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| 109 | cmp bx, MAX_LCHS_CYLINDERS ; Need to shift? |
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| 110 | jbe SHORT .LimitHeadsTo255 ; If not, return |
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| 111 | inc cx ; Increment shift count |
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| 112 | shr bx, 1 ; Halve cylinders |
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| 113 | shl dx, 1 ; Double heads |
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| 114 | jmp SHORT .ShiftLoop |
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| 115 | .LimitHeadsTo255: ; DOS does not support drives with 256 heads |
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| 116 | sub dl, dh ; BH set only when 256 logical heads |
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| 117 | xor dh, dh |
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| 118 | ret |
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| 119 | |
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| 120 | |
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| 121 | ;-------------------------------------------------------------------- |
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[3] | 122 | ; AccessDPT_TestIdeVarsFlagsForMasterOrSlaveDrive |
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| 123 | ; Parameters: |
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| 124 | ; AX: Bitmask to test DRVPARAMS.wFlags |
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| 125 | ; DS:DI: Ptr to Disk Parameter Table |
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| 126 | ; Returns: |
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| 127 | ; ZF: Set if tested bit was zero |
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| 128 | ; Cleared if tested bit was non-zero |
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| 129 | ; CF: 0 |
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| 130 | ; Corrupts registers: |
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| 131 | ; BX |
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| 132 | ;-------------------------------------------------------------------- |
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| 133 | ALIGN JUMP_ALIGN |
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| 134 | AccessDPT_TestIdeVarsFlagsForMasterOrSlaveDrive: |
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| 135 | call AccessDPT_GetPointerToDRVPARAMStoCSBX |
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| 136 | test [cs:bx+DRVPARAMS.wFlags], ax |
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| 137 | ret |
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| 138 | |
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| 139 | ;-------------------------------------------------------------------- |
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| 140 | ; Returns pointer to DRVPARAMS for master or slave drive. |
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| 141 | ; |
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| 142 | ; AccessDPT_GetPointerToDRVPARAMStoCSBX |
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| 143 | ; Parameters: |
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| 144 | ; DS:DI: Ptr to Disk Parameter Table |
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| 145 | ; Returns: |
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| 146 | ; CS:BX: Ptr to DRVPARAMS |
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| 147 | ; Corrupts registers: |
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| 148 | ; Nothing |
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| 149 | ;-------------------------------------------------------------------- |
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| 150 | ALIGN JUMP_ALIGN |
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| 151 | AccessDPT_GetPointerToDRVPARAMStoCSBX: |
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[150] | 152 | eMOVZX bx, [di+DPT.bIdevarsOffset] ; CS:BX points to IDEVARS |
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| 153 | add bx, BYTE IDEVARS.drvParamsMaster ; CS:BX points to Master Drive DRVPARAMS |
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[158] | 154 | test BYTE [di+DPT.bFlagsLow], FLGL_DPT_SLAVE |
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[150] | 155 | jz SHORT .ReturnPointerToDRVPARAMS |
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| 156 | add bx, BYTE DRVPARAMS_size ; CS:BX points to Slave Drive DRVPARAMS |
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| 157 | .ReturnPointerToDRVPARAMS: |
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[3] | 158 | ret |
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