| [90] | 1 | ; Project name : XTIDE Universal BIOS |
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| [3] | 2 | ; Description : Int 19h BIOS functions for Boot Menu. |
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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 | ; Initial Boot Menu Loader. |
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| 9 | ; Prepares BOOTVARS for displaying Boot Menu and accepting |
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| 10 | ; callbacks from INT 18h and 19h. |
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| 11 | ; |
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| 12 | ; Int19hMenu_BootLoader |
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| 13 | ; Parameters: |
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| 14 | ; Nothing |
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| 15 | ; Returns: |
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| 16 | ; Jumps to Int19hMenu_Display, then never returns |
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| 17 | ;-------------------------------------------------------------------- |
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| 18 | ALIGN JUMP_ALIGN |
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| 19 | Int19hMenu_BootLoader: |
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| 20 | LOAD_BDA_SEGMENT_TO ds, ax |
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| 21 | call BootVars_StorePostStackPointer |
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| 22 | |
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| 23 | ; Install new INT 19h handler now that BOOTVARS has been initialized |
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| [96] | 24 | mov WORD [INTV_BOOTSTRAP*4], DisplayBootMenu |
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| [3] | 25 | mov WORD [INTV_BOOTSTRAP*4+2], cs |
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| [96] | 26 | ; Fall to DisplayBootMenu |
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| [3] | 27 | |
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| 28 | ;-------------------------------------------------------------------- |
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| [96] | 29 | ; DisplayBootMenu |
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| [3] | 30 | ; Parameters: |
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| 31 | ; Nothing |
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| 32 | ; Returns: |
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| 33 | ; Never returns |
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| 34 | ;-------------------------------------------------------------------- |
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| 35 | ALIGN JUMP_ALIGN |
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| [96] | 36 | DisplayBootMenu: |
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| [3] | 37 | call BootVars_SwitchToBootMenuStack |
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| 38 | call RamVars_GetSegmentToDS |
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| [96] | 39 | ; Fall to .ProcessMenuSelectionsUntilBootable |
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| [3] | 40 | |
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| 41 | ;-------------------------------------------------------------------- |
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| [96] | 42 | ; .ProcessMenuSelectionsUntilBootable |
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| [3] | 43 | ; Parameters: |
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| 44 | ; DS: RAMVARS segment |
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| 45 | ; Returns: |
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| 46 | ; Never returns |
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| 47 | ;-------------------------------------------------------------------- |
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| 48 | ALIGN JUMP_ALIGN |
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| [96] | 49 | .ProcessMenuSelectionsUntilBootable: |
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| [95] | 50 | call BootMenu_DisplayAndReturnSelection |
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| 51 | call DriveXlate_ToOrBack ; Translate drive number |
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| [96] | 52 | call BootSector_TryToLoadFromDriveDL |
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| 53 | jnc SHORT .ProcessMenuSelectionsUntilBootable ; Boot failure, show menu again |
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| [3] | 54 | call BootVars_SwitchBackToPostStack |
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| [96] | 55 | ; Fall to JumpToBootSector |
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| [3] | 56 | |
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| [96] | 57 | ;-------------------------------------------------------------------- |
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| 58 | ; JumpToBootSector |
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| 59 | ; Parameters: |
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| 60 | ; DL: Drive to boot from (translated, 00h or 80h) |
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| 61 | ; ES:BX: Ptr to boot sector |
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| 62 | ; Returns: |
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| 63 | ; Never returns |
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| 64 | ;-------------------------------------------------------------------- |
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| 65 | ALIGN JUMP_ALIGN |
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| 66 | JumpToBootSector: |
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| 67 | push es ; Push boot sector segment |
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| 68 | push bx ; Push boot sector offset |
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| 69 | call ClearSegmentsForBoot |
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| 70 | xor dh, dh ; Device supported by INT 13h |
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| 71 | retf |
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| [3] | 72 | |
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| [96] | 73 | |
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| [3] | 74 | ;-------------------------------------------------------------------- |
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| [95] | 75 | ; Int19hMenu_RomBoot |
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| [3] | 76 | ; Parameters: |
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| 77 | ; DS: RAMVARS segment |
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| 78 | ; Returns: |
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| [95] | 79 | ; Never returns |
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| [3] | 80 | ;-------------------------------------------------------------------- |
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| 81 | ALIGN JUMP_ALIGN |
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| [95] | 82 | Int19hMenu_RomBoot: |
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| [3] | 83 | call BootVars_SwitchBackToPostStack |
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| [96] | 84 | call ClearSegmentsForBoot |
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| [95] | 85 | int INTV_BOOT_FAILURE ; Never returns |
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| [96] | 86 | |
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| 87 | |
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| 88 | ;-------------------------------------------------------------------- |
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| 89 | ; ClearSegmentsForBoot |
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| 90 | ; Parameters: |
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| 91 | ; Nothing |
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| 92 | ; Returns: |
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| 93 | ; DS=ES: Zero |
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| 94 | ; Corrupts registers: |
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| 95 | ; AX |
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| 96 | ;-------------------------------------------------------------------- |
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| 97 | ALIGN JUMP_ALIGN |
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| 98 | ClearSegmentsForBoot: |
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| 99 | xor ax, ax |
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| 100 | mov ds, ax |
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| 101 | mov es, ax |
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| 102 | ret |
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