[90] | 1 | ; Project name : XTIDE Universal BIOS |
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[3] | 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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[97] | 15 | ; DS: RAMVARS segment |
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[3] | 16 | ; Corrupts registers: |
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[97] | 17 | ; AX, CX, DI |
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[3] | 18 | ;-------------------------------------------------------------------- |
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| 19 | RamVars_Initialize: |
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[90] | 20 | push es |
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[97] | 21 | ; Fall to .StealMemoryForRAMVARS |
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[3] | 22 | |
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| 23 | ;-------------------------------------------------------------------- |
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[33] | 24 | ; .StealMemoryForRAMVARS |
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[3] | 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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[33] | 32 | .StealMemoryForRAMVARS: |
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[241] | 33 | mov ax, LITE_MODE_RAMVARS_SEGMENT |
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[3] | 34 | test BYTE [cs:ROMVARS.wFlags], FLG_ROMVARS_FULLMODE |
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[97] | 35 | jz SHORT .InitializeRamvars ; No need to steal RAM |
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[3] | 36 | |
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[116] | 37 | LOAD_BDA_SEGMENT_TO ds, ax, ! ; Zero AX |
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[3] | 38 | mov al, [cs:ROMVARS.bStealSize] |
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[33] | 39 | sub [BDA.wBaseMem], ax |
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| 40 | mov ax, [BDA.wBaseMem] |
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[97] | 41 | eSHL_IM ax, 6 ; Segment to first stolen kB (*=40h) |
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[150] | 42 | ; Fall to .InitializeRamvars |
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[3] | 43 | |
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[33] | 44 | ;-------------------------------------------------------------------- |
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[97] | 45 | ; .InitializeRamvars |
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[33] | 46 | ; Parameters: |
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[241] | 47 | ; AX: RAMVARS segment |
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[97] | 48 | ; Returns: |
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[33] | 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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[97] | 53 | .InitializeRamvars: |
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[241] | 54 | mov ds, ax |
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| 55 | mov es, ax |
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[97] | 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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[150] | 59 | mov WORD [RAMVARS.wSignature], RAMVARS_SIGNATURE |
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[97] | 60 | ; Fall to .InitializeDriveTranslationAndReturn |
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[3] | 61 | |
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[97] | 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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[33] | 74 | |
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[97] | 75 | |
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[3] | 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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[33] | 92 | jnz SHORT .GetStolenSegmentToDS |
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[181] | 93 | %ifndef USE_186 |
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[150] | 94 | mov di, LITE_MODE_RAMVARS_SEGMENT |
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[3] | 95 | mov ds, di |
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[181] | 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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[3] | 100 | ret |
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| 101 | |
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| 102 | ALIGN JUMP_ALIGN |
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[33] | 103 | .GetStolenSegmentToDS: |
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[3] | 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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[33] | 106 | eSHL_IM di, 6 ; Segment to first stolen kB (*=40h) |
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[3] | 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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[150] | 111 | cmp WORD [RAMVARS.wSignature], RAMVARS_SIGNATURE |
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[3] | 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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[258] | 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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[3] | 127 | ; Corrupts registers: |
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[155] | 128 | ; Nothing |
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[3] | 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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[258] | 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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[3] | 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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[258] | 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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[3] | 154 | ; Corrupts registers: |
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[148] | 155 | ; Nothing |
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[3] | 156 | ;-------------------------------------------------------------------- |
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| 157 | ALIGN JUMP_ALIGN |
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| 158 | RamVars_IsDriveHandledByThisBIOS: |
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[148] | 159 | push ax |
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[258] | 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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[148] | 185 | pop ax |
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[258] | 186 | .CFAlreadyClear_IsHandledByOurBIOS: |
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[3] | 187 | ret |
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| 188 | |
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[258] | 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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[3] | 199 | |
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| 200 | ;-------------------------------------------------------------------- |
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[258] | 201 | ; RamVars_GetHardDiskCountFromBDAtoAX |
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[3] | 202 | ; Parameters: |
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| 203 | ; DS: RAMVARS segment |
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| 204 | ; Returns: |
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[258] | 205 | ; AX: Total hard disk count |
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[3] | 206 | ; Corrupts registers: |
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[258] | 207 | ; CX |
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[116] | 208 | ;-------------------------------------------------------------------- |
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[3] | 209 | ALIGN JUMP_ALIGN |
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[258] | 210 | RamVars_GetHardDiskCountFromBDAtoAX: |
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[3] | 211 | push es |
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[32] | 212 | |
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[258] | 213 | LOAD_BDA_SEGMENT_TO es, ax |
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| 214 | call RamVars_GetCountOfKnownDrivesToAX |
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[181] | 215 | mov cl, [es:BDA.bHDCount] |
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[258] | 216 | MAX_U al, cl |
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| 217 | |
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[3] | 218 | pop es |
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| 219 | ret |
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[32] | 220 | |
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| 221 | ;-------------------------------------------------------------------- |
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[258] | 222 | ; RamVars_GetCountOfKnownDrivesToAX |
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[32] | 223 | ; Parameters: |
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| 224 | ; DS: RAMVARS segment |
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| 225 | ; Returns: |
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[258] | 226 | ; AX: Total hard disk count |
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[32] | 227 | ; Corrupts registers: |
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[258] | 228 | ; None |
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[116] | 229 | ;-------------------------------------------------------------------- |
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[32] | 230 | ALIGN JUMP_ALIGN |
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[258] | 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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[32] | 236 | ret |
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[258] | 237 | |
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[33] | 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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[116] | 246 | ;-------------------------------------------------------------------- |
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[258] | 247 | ALIGN JUMP_ALIGN |
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[33] | 248 | RamVars_GetIdeControllerCountToCX: |
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[99] | 249 | eMOVZX cx, BYTE [cs:ROMVARS.bIdeCnt] |
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[33] | 250 | ret |
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[258] | 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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