| 1 | ; Project name : XTIDE Universal BIOS
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| 2 | ; Description : Functions for accessings RAMVARS.
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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 | ; Initializes RAMVARS.
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| 9 | ; Drive detection can be started after this function returns.
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| 10 | ;
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| 11 | ; RamVars_Initialize
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| 12 | ; Parameters:
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| 13 | ; Nothing
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| 14 | ; Returns:
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| 15 | ; DS: RAMVARS segment
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| 16 | ; Corrupts registers:
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| 17 | ; AX, CX, DI
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| 18 | ;--------------------------------------------------------------------
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| 19 | RamVars_Initialize:
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| 20 | push es
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| 21 | ; Fall to .StealMemoryForRAMVARS
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| 22 |
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| 23 | ;--------------------------------------------------------------------
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| 24 | ; .StealMemoryForRAMVARS
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| 25 | ; Parameters:
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| 26 | ; Nothing
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| 27 | ; Returns:
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| 28 | ; DS: RAMVARS segment
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| 29 | ; Corrupts registers:
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| 30 | ; AX
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| 31 | ;--------------------------------------------------------------------
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| 32 | .StealMemoryForRAMVARS:
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| 33 | mov ax, LITE_MODE_RAMVARS_SEGMENT
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| 34 | test BYTE [cs:ROMVARS.wFlags], FLG_ROMVARS_FULLMODE
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| 35 | jz SHORT .InitializeRamvars ; No need to steal RAM
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| 36 |
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| 37 | LOAD_BDA_SEGMENT_TO ds, ax, ! ; Zero AX
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| 38 | mov al, [cs:ROMVARS.bStealSize]
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| 39 | sub [BDA.wBaseMem], ax
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| 40 | mov ax, [BDA.wBaseMem]
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| 41 | eSHL_IM ax, 6 ; Segment to first stolen kB (*=40h)
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| 42 | ; Fall to .InitializeRamvars
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| 43 |
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| 44 | ;--------------------------------------------------------------------
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| 45 | ; .InitializeRamvars
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| 46 | ; Parameters:
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| 47 | ; AX: RAMVARS segment
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| 48 | ; Returns:
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| 49 | ; DS: RAMVARS segment
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| 50 | ; Corrupts registers:
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| 51 | ; AX, CX, DI, ES
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| 52 | ;--------------------------------------------------------------------
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| 53 | .InitializeRamvars:
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| 54 | mov ds, ax
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| 55 | mov es, ax
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| 56 | mov cx, RAMVARS_size
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| 57 | xor di, di
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| 58 | call Memory_ZeroESDIwithSizeInCX
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| 59 | mov WORD [RAMVARS.wSignature], RAMVARS_SIGNATURE
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| 60 | ; Fall to .InitializeDriveTranslationAndReturn
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| 61 |
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| 62 | ;--------------------------------------------------------------------
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| 63 | ; .InitializeDriveTranslationAndReturn
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| 64 | ; Parameters:
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| 65 | ; DS: RAMVARS segment
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| 66 | ; Returns:
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| 67 | ; Nothing
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| 68 | ; Corrupts registers:
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| 69 | ; AX
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| 70 | ;--------------------------------------------------------------------
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| 71 | .InitializeDriveTranslationAndReturn:
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| 72 | pop es
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| 73 | jmp DriveXlate_Reset
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| 74 |
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| 75 |
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| 76 | ;--------------------------------------------------------------------
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| 77 | ; Returns segment to RAMVARS.
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| 78 | ; RAMVARS might be located at the top of interrupt vectors (0030:0000h)
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| 79 | ; or at the top of system base RAM.
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| 80 | ;
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| 81 | ; RamVars_GetSegmentToDS
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| 82 | ; Parameters:
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| 83 | ; Nothing
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| 84 | ; Returns:
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| 85 | ; DS: RAMVARS segment
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| 86 | ; Corrupts registers:
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| 87 | ; DI
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| 88 | ;--------------------------------------------------------------------
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| 89 | ALIGN JUMP_ALIGN
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| 90 | RamVars_GetSegmentToDS:
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| 91 | test BYTE [cs:ROMVARS.wFlags], FLG_ROMVARS_FULLMODE
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| 92 | jnz SHORT .GetStolenSegmentToDS
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| 93 | %ifndef USE_186
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| 94 | mov di, LITE_MODE_RAMVARS_SEGMENT
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| 95 | mov ds, di
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| 96 | %else
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| 97 | push LITE_MODE_RAMVARS_SEGMENT
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| 98 | pop ds
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| 99 | %endif
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| 100 | ret
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| 101 |
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| 102 | ALIGN JUMP_ALIGN
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| 103 | .GetStolenSegmentToDS:
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| 104 | LOAD_BDA_SEGMENT_TO ds, di
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| 105 | mov di, [BDA.wBaseMem] ; Load available base memory size in kB
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| 106 | eSHL_IM di, 6 ; Segment to first stolen kB (*=40h)
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| 107 | ALIGN JUMP_ALIGN
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| 108 | .LoopStolenKBs:
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| 109 | mov ds, di ; EBDA segment to DS
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| 110 | add di, BYTE 64 ; DI to next stolen kB
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| 111 | cmp WORD [RAMVARS.wSignature], RAMVARS_SIGNATURE
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| 112 | jne SHORT .LoopStolenKBs ; Loop until sign found (always found eventually)
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| 113 | ret
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| 114 |
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| 115 |
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| 116 | ;--------------------------------------------------------------------
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| 117 | ; Checks if INT 13h function is handled by this BIOS.
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| 118 | ;
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| 119 | ; RamVars_IsFunctionHandledByThisBIOS
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| 120 | ; Parameters:
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| 121 | ; AH: INT 13h function number
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| 122 | ; DL: Drive number
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| 123 | ; DS: RAMVARS segment
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| 124 | ; Returns:
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| 125 | ; CF: Cleared if function is handled by this BIOS
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| 126 | ; Set if function belongs to some other BIOS
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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 | RamVars_IsFunctionHandledByThisBIOS:
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| 132 | test ah, ah ; Reset for all floppy and hard disk drives?
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| 133 | jz SHORT RamVars_IsDriveHandledByThisBIOS.CFAlreadyClear_IsHandledByOurBIOS
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| 134 | cmp ah, 08h
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| 135 | %ifdef MODULE_SERIAL_FLOPPY
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| 136 | ; we handle all traffic for function 08h, as we need to wrap both hard disk and floppy drive counts
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| 137 | je SHORT RamVars_IsDriveHandledByThisBIOS.CFAlreadyClear_IsHandledByOurBIOS
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| 138 | %else
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| 139 | ; we handle all *hard disk* traffic for function 08h, as we need to wrap the hard disk drive count
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| 140 | je SHORT RamVars_IsDriveHandledByThisBIOS.IsDriveAHardDisk
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| 141 | %endif
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| 142 | ;;; fall-through
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| 143 |
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| 144 | ;--------------------------------------------------------------------
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| 145 | ; Checks if drive is handled by this BIOS.
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| 146 | ;
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| 147 | ; RamVars_IsDriveHandledByThisBIOS
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| 148 | ; Parameters:
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| 149 | ; DL: Drive number
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| 150 | ; DS: RAMVARS segment
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| 151 | ; Returns:
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| 152 | ; CF: Cleared if drive is handled by this BIOS
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| 153 | ; Set if drive belongs to some other BIOS
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| 154 | ; Corrupts registers:
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| 155 | ; Nothing
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| 156 | ;--------------------------------------------------------------------
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| 157 | ALIGN JUMP_ALIGN
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| 158 | RamVars_IsDriveHandledByThisBIOS:
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| 159 | push ax
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| 160 |
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| 161 | mov ax, [RAMVARS.wDrvCntAndFirst] ; Drive count to AH, First number to AL
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| 162 | add ah, al ; One past last drive to AH
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| 163 | cmp dl, ah ; Above last supported?
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| 164 | jae SHORT .HardDiskIsNotHandledByThisBIOS
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| 165 | .TestLowLimit:
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| 166 | cmp dl, al ; Below first supported?
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| 167 | jae SHORT .CFAlreadyClear_IsHandledByOurBIOS_PopAX ; note that CF is clear if the branch is taken
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| 168 |
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| 169 | .HardDiskIsNotHandledByThisBIOS:
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| 170 | %ifdef MODULE_SERIAL_FLOPPY
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| 171 | call RamVars_UnpackFlopCntAndFirstToAL
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| 172 | cbw ; normally 0h, could be ffh if no drives present
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| 173 | adc ah, al ; if no drives present, still ffh (ffh + ffh + 1 = ffh)
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| 174 | js SHORT .DiskIsNotHandledByThisBIOS
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| 175 | cmp ah, dl
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| 176 | jz SHORT .CFAlreadyClear_IsHandledByOurBIOS_PopAX
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| 177 | cmp al, dl
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| 178 | jz SHORT .CFAlreadyClear_IsHandledByOurBIOS_PopAX
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| 179 | .DiskIsNotHandledByThisBIOS:
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| 180 | %endif
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| 181 |
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| 182 | stc ; Is not supported by our BIOS
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| 183 |
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| 184 | .CFAlreadyClear_IsHandledByOurBIOS_PopAX:
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| 185 | pop ax
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| 186 | .CFAlreadyClear_IsHandledByOurBIOS:
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| 187 | ret
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| 188 |
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| 189 | %ifndef MODULE_SERIAL_FLOPPY
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| 190 | ;
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| 191 | ; Note that we could have just checked for the high order bit in dl, but with the needed STC and jumps,
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| 192 | ; leveraging the code above resulted in space savings.
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| 193 | ;
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| 194 | .IsDriveAHardDisk:
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| 195 | push ax ; match stack at the top of routine
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| 196 | mov al, 80h ; to catch all hard disks, lower limit is 80h vs. bFirstDrv
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| 197 | jmp .TestLowLimit ; and there is no need to test a high limit
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| 198 | %endif
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| 199 |
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| 200 | ;--------------------------------------------------------------------
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| 201 | ; RamVars_GetHardDiskCountFromBDAtoAX
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| 202 | ; Parameters:
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| 203 | ; DS: RAMVARS segment
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| 204 | ; Returns:
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| 205 | ; AX: Total hard disk count
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| 206 | ; Corrupts registers:
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| 207 | ; CX
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| 208 | ;--------------------------------------------------------------------
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| 209 | ALIGN JUMP_ALIGN
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| 210 | RamVars_GetHardDiskCountFromBDAtoAX:
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| 211 | push es
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| 212 |
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| 213 | LOAD_BDA_SEGMENT_TO es, ax
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| 214 | call RamVars_GetCountOfKnownDrivesToAX
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| 215 | mov cl, [es:BDA.bHDCount]
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| 216 | MAX_U al, cl
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| 217 |
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| 218 | pop es
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| 219 | ret
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| 220 |
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| 221 | ;--------------------------------------------------------------------
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| 222 | ; RamVars_GetCountOfKnownDrivesToAX
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| 223 | ; Parameters:
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| 224 | ; DS: RAMVARS segment
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| 225 | ; Returns:
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| 226 | ; AX: Total hard disk count
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| 227 | ; Corrupts registers:
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| 228 | ; None
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| 229 | ;--------------------------------------------------------------------
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| 230 | ALIGN JUMP_ALIGN
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| 231 | RamVars_GetCountOfKnownDrivesToAX:
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| 232 | mov ax, [RAMVARS.wDrvCntAndFirst]
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| 233 | add al, ah
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| 234 | and al, 7fh
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| 235 | cbw
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| 236 | ret
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| 237 |
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| 238 | ;--------------------------------------------------------------------
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| 239 | ; RamVars_GetIdeControllerCountToCX
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| 240 | ; Parameters:
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| 241 | ; Nothing
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| 242 | ; Returns:
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| 243 | ; CX: Number of IDE controllers to handle
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| 244 | ; Corrupts registers:
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| 245 | ; Nothing
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| 246 | ;--------------------------------------------------------------------
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| 247 | ALIGN JUMP_ALIGN
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| 248 | RamVars_GetIdeControllerCountToCX:
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| 249 | eMOVZX cx, BYTE [cs:ROMVARS.bIdeCnt]
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| 250 | ret
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| 251 |
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| 252 | %ifdef MODULE_SERIAL_FLOPPY
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| 253 | ;--------------------------------------------------------------------
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| 254 | ; RamVars_UnpackFlopCntAndFirstToAL
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| 255 | ; Parameters:
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| 256 | ; Nothing
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| 257 | ; Returns:
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| 258 | ; AL: First floppy drive number supported
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| 259 | ; CF: Number of floppy drives supported (clear = 1, set = 2)
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| 260 | ; Corrupts registers:
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| 261 | ; Nothing
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| 262 | ;--------------------------------------------------------------------
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| 263 | ALIGN JUMP_ALIGN
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| 264 | RamVars_UnpackFlopCntAndFirstToAL:
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| 265 | mov al, [RAMVARS.xlateVars+XLATEVARS.bFlopCntAndFirst]
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| 266 | sar al, 1
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| 267 | ret
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| 268 | %endif
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