1 | ; Project name : XTIDE Universal BIOS |
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2 | ; Description : Int 13h handler that is used by MODULE_MFM_COMPATIBILITY. |
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3 | ; It is placed between XUB Int 13h handler and system INT 13h handler |
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4 | ; to hide XUB from MFM controllers whose BIOS assumes they handle |
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5 | ; all hard drives on the system. |
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6 | |
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7 | ; |
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8 | ; XTIDE Universal BIOS and Associated Tools |
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9 | ; Copyright (C) 2009-2010 by Tomi Tilli, 2011-2013 by XTIDE Universal BIOS Team. |
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10 | ; |
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11 | ; This program is free software; you can redistribute it and/or modify |
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12 | ; it under the terms of the GNU General Public License as published by |
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13 | ; the Free Software Foundation; either version 2 of the License, or |
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14 | ; (at your option) any later version. |
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15 | ; |
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16 | ; This program is distributed in the hope that it will be useful, |
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17 | ; but WITHOUT ANY WARRANTY; without even the implied warranty of |
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18 | ; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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19 | ; GNU General Public License for more details. |
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20 | ; Visit http://www.gnu.org/licenses/old-licenses/gpl-2.0.html |
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21 | ; |
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22 | |
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23 | ; Section containing code |
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24 | SECTION .text |
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25 | |
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26 | |
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27 | ;-------------------------------------------------------------------- |
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28 | ; Int 13h software interrupt handler for MFM compatibility. |
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29 | ; |
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30 | ; Some MFM controllers require that BDA drive count is what they have set. |
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31 | ; The purpose for this handler is to restore BDA drive count to what MFM controller |
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32 | ; expects and then call MFM controller INT 13h. |
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33 | ; |
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34 | ; Int13hMFMcompatibilityHandler |
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35 | ; Parameters: |
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36 | ; Any INT 13h function and parameters |
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37 | ;-------------------------------------------------------------------- |
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38 | ALIGN JUMP_ALIGN |
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39 | Int13hMFMcompatibilityHandler: |
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40 | eENTER 6, 0 |
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41 | push es |
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42 | push ds |
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43 | push di |
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44 | |
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45 | LOAD_BDA_SEGMENT_TO es, di |
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46 | call RamVars_GetSegmentToDS |
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47 | |
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48 | ; Remove our drives from BDA drive count |
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49 | push ax |
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50 | mov al, [RAMVARS.bDrvCnt] |
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51 | mov [bp-2], al ; Store our drive count for later use |
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52 | sub [es:HDBDA.bHDCount], al |
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53 | pop ax |
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54 | |
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55 | ; Copy MFM controller INT 13h address to stack |
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56 | les di, [RAMVARS.fpMFMint13h] |
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57 | mov [bp-4], es |
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58 | mov [bp-6], di |
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59 | |
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60 | ; Restore registers so we can call MFM int 13h |
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61 | pop di |
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62 | pop ds |
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63 | pop es |
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64 | |
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65 | pushf ; Push flags to simulate INT |
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66 | call FAR [bp-6] |
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67 | |
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68 | ; Now we can restore BDA drive count |
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69 | push ds |
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70 | push ax |
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71 | lahf ; Get return flags to AH |
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72 | mov [bp-12], ah ; Store return flags to be popped by iret |
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73 | LOAD_BDA_SEGMENT_TO ds, ax |
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74 | mov al, [bp-2] |
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75 | add [HDBDA.bHDCount], al |
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76 | pop ax |
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77 | pop ds |
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78 | |
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79 | ; Return from this handler |
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80 | eLEAVE |
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81 | iret |
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