| 1 | ; Project name : XTIDE Universal BIOS
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| 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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| 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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| 36 | test BYTE [di+DPT.bFlagsLow], FLGL_DPT_ENABLE_IRQ
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| 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_GetLCHStoAXBLBH
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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 | ; AX: Number of L-CHS cylinders
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| 49 | ; BL: Number of L-CHS heads
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| 50 | ; BH: Number of L-CHS sectors per track
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| 51 | ; Corrupts registers:
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| 52 | ; CX, DX
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| 53 | ;--------------------------------------------------------------------
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| 54 | AccessDPT_GetLCHStoAXBLBH:
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| 55 | ; Return LBA-assisted CHS if LBA addressing used
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| 56 | test BYTE [di+DPT.bFlagsLow], FLG_DRVNHEAD_LBA
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| 57 | jz SHORT .ConvertPchsToLchs
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| 58 |
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| 59 | call AccessDPT_GetLbaSectorCountToBXDXAX
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| 60 | call AtaID_GetLbaAssistedCHStoDXAXBLBH
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| 61 | test dx, dx
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| 62 | jnz SHORT .LimitAXtoMaxLCHScylinders
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| 63 | cmp ax, MAX_LCHS_CYLINDERS
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| 64 | jb SHORT .returnLCHS
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| 65 | .LimitAXtoMaxLCHScylinders:
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| 66 | mov ax, MAX_LCHS_CYLINDERS
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| 67 | .returnLCHS:
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| 68 | ret
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| 69 |
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| 70 | .ConvertPchsToLchs:
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| 71 | mov ax, [di+DPT.wPchsCylinders]
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| 72 | mov bx, [di+DPT.wPchsHeadsAndSectors]
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| 73 | ; Fall to AccessDPT_ShiftPCHinAXBLtoLCH
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| 74 |
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| 75 |
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| 76 | ;--------------------------------------------------------------------
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| 77 | ; AccessDPT_ShiftPCHinAXBLtoLCH
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| 78 | ; Parameters:
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| 79 | ; AX: P-CHS cylinders (1...16383)
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| 80 | ; BL: P-CHS heads (1...16)
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| 81 | ; Returns:
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| 82 | ; AX: Number of L-CHS cylinders (1...1024)
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| 83 | ; BL: Number of L-CHS heads (1...255)
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| 84 | ; CX: Number of bits shifted (4 at most)
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| 85 | ; Corrupts registers:
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| 86 | ; Nothing
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| 87 | ;--------------------------------------------------------------------
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| 88 | AccessDPT_ShiftPCHinAXBLtoLCH:
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| 89 | xor cx, cx
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| 90 | .ShiftLoop:
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| 91 | cmp ax, MAX_LCHS_CYLINDERS ; Need to shift?
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| 92 | jbe SHORT .Return ; If not, return
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| 93 | inc cx ; Increment shift count
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| 94 | shr ax, 1 ; Halve cylinders
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| 95 | shl bl, 1 ; Double heads
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| 96 | jnz SHORT .ShiftLoop ; Falls through only on the last (4th) iteration and only if BL was 16 on entry
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| 97 | dec bl ; DOS doesn't support drives with 256 heads so we limit heads to 255
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| 98 | ; We can save a byte here by using DEC BX if we don't care about BH
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| 99 | .Return:
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| 100 | ret
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| 101 |
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| 102 |
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| 103 | ;--------------------------------------------------------------------
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| 104 | ; AccessDPT_GetLbaSectorCountToBXDXAX
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| 105 | ; Parameters:
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| 106 | ; DS:DI: Ptr to Disk Parameter Table
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| 107 | ; Returns:
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| 108 | ; BX:DX:AX: 48-bit sector count
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| 109 | ; Corrupts registers:
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| 110 | ; Nothing
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| 111 | ;--------------------------------------------------------------------
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| 112 | AccessDPT_GetLbaSectorCountToBXDXAX:
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| 113 | mov ax, [di+DPT.twLbaSectors]
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| 114 | mov dx, [di+DPT.twLbaSectors+2]
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| 115 | mov bx, [di+DPT.twLbaSectors+4]
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| 116 | ret
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| 117 |
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| 118 |
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| 119 | ;--------------------------------------------------------------------
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| 120 | ; Returns pointer to DRVPARAMS for master or slave drive.
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| 121 | ;
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| 122 | ; AccessDPT_GetPointerToDRVPARAMStoCSBX
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| 123 | ; Parameters:
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| 124 | ; DS:DI: Ptr to Disk Parameter Table
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| 125 | ; Returns:
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| 126 | ; CS:BX: Ptr to DRVPARAMS
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| 127 | ; Corrupts registers:
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| 128 | ; Nothing
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| 129 | ;--------------------------------------------------------------------
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| 130 | ALIGN JUMP_ALIGN
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| 131 | AccessDPT_GetPointerToDRVPARAMStoCSBX:
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| 132 | eMOVZX bx, [di+DPT.bIdevarsOffset] ; CS:BX points to IDEVARS
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| 133 | add bx, BYTE IDEVARS.drvParamsMaster ; CS:BX points to Master Drive DRVPARAMS
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| 134 | test BYTE [di+DPT.bFlagsLow], FLGL_DPT_SLAVE
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| 135 | jz SHORT .ReturnPointerToDRVPARAMS
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| 136 | add bx, BYTE DRVPARAMS_size ; CS:BX points to Slave Drive DRVPARAMS
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| 137 | .ReturnPointerToDRVPARAMS:
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| 138 | ret
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| 139 |
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| 140 | ;--------------------------------------------------------------------
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| 141 | ; AccessDPT_GetUnshiftedAddressModeToALZF
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| 142 | ; Parameters:
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| 143 | ; DS:DI: Ptr to Disk Parameter Table
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| 144 | ; Returns:
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| 145 | ; AL: Addressing Mode (L-CHS, P-CHS, LBA28, LBA48)
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| 146 | ; unshifted (still shifted where it is in bFlagsLow)
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| 147 | ; ZF: Set based on value in AL
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| 148 | ; Corrupts registers:
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| 149 | ; AL
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| 150 | ;--------------------------------------------------------------------
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| 151 | ;
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| 152 | ; Converted to a macro since only called in two places, and the call/ret overhead
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| 153 | ; is not worth it for these two instructions (4 bytes total)
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| 154 | ;
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| 155 | %macro AccessDPT_GetUnshiftedAddressModeToALZF 0
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| 156 | mov al, [di+DPT.bFlagsLow]
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| 157 | and al, MASKL_DPT_ADDRESSING_MODE
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| 158 | %endmacro
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