| 1 | ; Project name : XTIDE Universal BIOS
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| 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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| 8 | ; Finds pointer to first unused Disk Parameter Table.
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| 9 | ;
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| 10 | ; FindDPT_ForNewDriveToDSDI
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| 11 | ; Parameters:
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| 12 | ; DS: RAMVARS segment
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| 13 | ; Returns:
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| 14 | ; DS:DI: Ptr to first unused DPT
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| 15 | ; Corrupts registers:
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| 16 | ; DL
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| 17 | ;--------------------------------------------------------------------
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| 18 | ALIGN JUMP_ALIGN
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| 19 | FindDPT_ForNewDriveToDSDI:
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| 20 | mov dl, [RAMVARS.bFirstDrv]
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| 21 | add dl, [RAMVARS.bDrvCnt]
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| 22 | ; Fall to FindDPT_ForDriveNumber
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| 23 |
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| 24 |
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| 25 | ;--------------------------------------------------------------------
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| 26 | ; Finds Disk Parameter Table for drive number.
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| 27 | ; IDE Base Port address will be stored to RAMVARS if correct DPT is found.
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| 28 | ;
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| 29 | ; FindDPT_ForDriveNumber
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| 30 | ; Parameters:
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| 31 | ; DL: Drive number
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| 32 | ; DS: RAMVARS segment
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| 33 | ; Returns:
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| 34 | ; DS:DI: Ptr to DPT
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| 35 | ; Corrupts registers:
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| 36 | ; Nothing
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| 37 | ;--------------------------------------------------------------------
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| 38 | ALIGN JUMP_ALIGN
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| 39 | FindDPT_ForDriveNumber:
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| 40 | push dx
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| 41 | push ax
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| 42 |
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| 43 | mov al, LARGEST_DPT_SIZE
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| 44 | sub dl, [RAMVARS.bFirstDrv]
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| 45 | mul dl
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| 46 | add ax, BYTE RAMVARS_size
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| 47 | xchg di, ax
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| 48 |
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| 49 | pop ax
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| 50 | pop dx
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| 51 | ret
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| 52 |
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| 53 |
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| 54 | ;--------------------------------------------------------------------
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| 55 | ; Finds Disk Parameter Table for
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| 56 | ; Master or Slave drive at wanted port.
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| 57 | ;
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| 58 | ; FindDPT_ToDSDIForIdeMasterAtPortDX
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| 59 | ; FindDPT_ToDSDIForIdeSlaveAtPortDX
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| 60 | ; Parameters:
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| 61 | ; DX: IDE Base Port address
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| 62 | ; DS: RAMVARS segment
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| 63 | ; Returns:
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| 64 | ; DL: Drive number (if DPT found)
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| 65 | ; DS:DI: Ptr to DPT
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| 66 | ; CF: Set if wanted DPT found
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| 67 | ; Cleared if DPT not found
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| 68 | ; Corrupts registers:
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| 69 | ; SI
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| 70 | ;--------------------------------------------------------------------
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| 71 | ALIGN JUMP_ALIGN
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| 72 | FindDPT_ToDSDIForIdeMasterAtPortDX:
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| 73 | mov si, FindDPT_IterateToMasterAtPortCallback
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| 74 | jmp SHORT IterateAllDPTs
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| 75 |
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| 76 | ALIGN JUMP_ALIGN
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| 77 | FindDPT_ToDSDIForIdeSlaveAtPortDX:
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| 78 | mov si, FindDPT_IterateToSlaveAtPortCallback
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| 79 | jmp SHORT IterateAllDPTs
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| 80 |
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| 81 | ;--------------------------------------------------------------------
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| 82 | ; Iteration callback for finding DPT using
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| 83 | ; IDE base port for Master or Slave drive.
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| 84 | ;
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| 85 | ; FindDPT_IterateToSlaveAtPortCallback
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| 86 | ; FindDPT_IterateToMasterAtPortCallback
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| 87 | ; Parameters:
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| 88 | ; CH: Drive number
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| 89 | ; DX: IDE Base Port address
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| 90 | ; DS:DI: Ptr to DPT to examine
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| 91 | ; Returns:
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| 92 | ; DL: Drive number if correct DPT
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| 93 | ; CF: Set if wanted DPT found
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| 94 | ; Cleared if wrong DPT
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| 95 | ; Corrupts registers:
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| 96 | ; Nothing
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| 97 | ;--------------------------------------------------------------------
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| 98 | ALIGN JUMP_ALIGN
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| 99 | FindDPT_IterateToSlaveAtPortCallback:
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| 100 | test BYTE [di+DPT.wFlags], FLG_DPT_SLAVE ; Clears CF
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| 101 | jnz SHORT CompareBasePortAddress
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| 102 | ret ; Wrong DPT
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| 103 |
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| 104 | ALIGN JUMP_ALIGN
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| 105 | FindDPT_IterateToMasterAtPortCallback:
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| 106 | test BYTE [di+DPT.wFlags], FLG_DPT_SLAVE
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| 107 | jnz SHORT ReturnWrongDPT ; Return if slave drive
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| 108 |
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| 109 | CompareBasePortAddress:
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| 110 | push bx
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| 111 | eMOVZX bx, BYTE [di+DPT.bIdevarsOffset] ; CS:BX now points to IDEVARS
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| 112 | cmp dx, [cs:bx+IDEVARS.wPort] ; Wanted port?
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| 113 | pop bx
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| 114 | jne SHORT ReturnWrongDPT
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| 115 | mov dl, ch ; Return drive number in DL
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| 116 | stc ; Set CF since wanted DPT
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| 117 | ret
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| 118 | ReturnWrongDPT:
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| 119 | clc ; Clear CF since wrong DPT
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| 120 | ret
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| 121 |
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| 122 |
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| 123 | ;--------------------------------------------------------------------
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| 124 | ; Iterates all Disk Parameter Tables.
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| 125 | ;
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| 126 | ; IterateAllDPTs
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| 127 | ; Parameters:
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| 128 | ; BX,DX: Parameters to callback function
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| 129 | ; CS:SI: Ptr to callback function
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| 130 | ; DS: RAMVARS segment
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| 131 | ; Returns:
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| 132 | ; DS:DI: Ptr to wanted DPT (if found)
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| 133 | ; CF: Set if wanted DPT found
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| 134 | ; Cleared if DPT not found
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| 135 | ; Corrupts registers:
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| 136 | ; Nothing unless corrupted by callback function
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| 137 | ;--------------------------------------------------------------------
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| 138 | ALIGN JUMP_ALIGN
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| 139 | IterateAllDPTs:
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| 140 | push cx
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| 141 | mov cx, [RAMVARS.wDrvCntAndFirst]
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| 142 | jcxz .AllDptsIterated ; Return if no drives
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| 143 | call FindDPT_PointToFirstDPT ; Point DS:DI to first DPT
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| 144 | ALIGN JUMP_ALIGN
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| 145 | .LoopWhileDPTsLeft:
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| 146 | call si ; Is wanted DPT?
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| 147 | jc SHORT .AllDptsIterated ; If so, return
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| 148 | inc ch ; Increment drive number
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| 149 | add di, BYTE LARGEST_DPT_SIZE ; Point to next DPT
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| 150 | dec cl ; Decrement drives left
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| 151 | jnz SHORT .LoopWhileDPTsLeft
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| 152 | clc ; Clear CF since DPT not found
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| 153 | ALIGN JUMP_ALIGN
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| 154 | .AllDptsIterated:
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| 155 | pop cx
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| 156 | ret
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| 157 |
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| 158 |
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| 159 | ;--------------------------------------------------------------------
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| 160 | ; Sets DI to point to first Disk Parameter Table.
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| 161 | ;
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| 162 | ; FindDPT_PointToFirstDPT
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| 163 | ; Parameters:
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| 164 | ; Nothing
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| 165 | ; Returns:
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| 166 | ; DI: Offset to first DPT (even if unused)
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| 167 | ; Corrupts registers:
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| 168 | ; Nothing
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| 169 | ;--------------------------------------------------------------------
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| 170 | ALIGN JUMP_ALIGN
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| 171 | FindDPT_PointToFirstDPT:
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| 172 | mov di, RAMVARS_size
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| 173 | ret
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