| 1 | ; Project name : XTIDE Universal BIOS
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| 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 | ; Boot Menu Loader.
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| 9 | ;
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| 10 | ; Int19hMenu_BootLoader
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| 11 | ; Parameters:
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| 12 | ; Nothing
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| 13 | ; Returns:
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| 14 | ; Jumps to Int19hMenu_Display, then never returns
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| 15 | ;--------------------------------------------------------------------
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| 16 | ALIGN JUMP_ALIGN
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| 17 | Int19hMenu_BootLoader:
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| 18 | ; Store POST stack pointer
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| 19 | LOAD_BDA_SEGMENT_TO ds, ax
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| 20 | STORE_POST_STACK_POINTER
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| 21 | SWITCH_TO_BOOT_MENU_STACK
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| 22 | call RamVars_GetSegmentToDS
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| 23 | ; Fall to .InitializeDisplayForBootMenu
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| 24 |
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| 25 | ;--------------------------------------------------------------------
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| 26 | ; .InitializeDisplayForBootMenu
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| 27 | ; Parameters:
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| 28 | ; Nothing
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| 29 | ; Returns:
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| 30 | ; Nothing
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| 31 | ; Corrupts registers:
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| 32 | ; AX, DI
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| 33 | ;--------------------------------------------------------------------
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| 34 | .InitializeDisplayForBootMenu:
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| 35 | ; Change display mode if necessary
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| 36 | mov ax, [cs:ROMVARS.wDisplayMode] ; AH 00h = Set Video Mode
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| 37 | cmp al, DEFAULT_TEXT_MODE
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| 38 | je SHORT .InitializeDisplayLibrary
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| 39 | int BIOS_VIDEO_INTERRUPT_10h
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| 40 | .InitializeDisplayLibrary:
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| 41 | call BootMenuPrint_InitializeDisplayContext
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| 42 | ; Fall to .ProcessMenuSelectionsUntilBootable
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| 43 |
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| 44 | ;--------------------------------------------------------------------
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| 45 | ; .ProcessMenuSelectionsUntilBootable
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| 46 | ; Parameters:
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| 47 | ; DS: RAMVARS segment
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| 48 | ; Returns:
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| 49 | ; Never returns
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| 50 | ;--------------------------------------------------------------------
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| 51 | ALIGN JUMP_ALIGN
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| 52 | .ProcessMenuSelectionsUntilBootable:
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| 53 | call BootMenu_DisplayAndReturnSelection
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| 54 | call DriveXlate_ToOrBack ; Translate drive number
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| 55 | call BootSector_TryToLoadFromDriveDL
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| 56 | jnc SHORT .ProcessMenuSelectionsUntilBootable ; Boot failure, show menu again
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| 57 | SWITCH_BACK_TO_POST_STACK
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| 58 | ; Fall to JumpToBootSector
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| 59 |
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| 60 | ;--------------------------------------------------------------------
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| 61 | ; JumpToBootSector
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| 62 | ; Parameters:
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| 63 | ; DL: Drive to boot from (translated, 00h or 80h)
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| 64 | ; ES:BX: Ptr to boot sector
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| 65 | ; Returns:
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| 66 | ; Never returns
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| 67 | ;--------------------------------------------------------------------
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| 68 | ALIGN JUMP_ALIGN
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| 69 | JumpToBootSector:
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| 70 | push es ; Push boot sector segment
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| 71 | push bx ; Push boot sector offset
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| 72 | call ClearSegmentsForBoot
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| 73 | retf
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| 74 |
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| 75 |
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| 76 | ;--------------------------------------------------------------------
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| 77 | ; Int19hMenu_RomBoot
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| 78 | ; Parameters:
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| 79 | ; DS: RAMVARS segment
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| 80 | ; Returns:
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| 81 | ; Never returns
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| 82 | ;--------------------------------------------------------------------
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| 83 | ALIGN JUMP_ALIGN
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| 84 | Int19hMenu_RomBoot:
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| 85 | SWITCH_BACK_TO_POST_STACK
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| 86 | call ClearSegmentsForBoot
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| 87 | int BIOS_BOOT_FAILURE_INTERRUPT_18h ; Never returns
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| 88 |
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| 89 |
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| 90 | ;--------------------------------------------------------------------
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| 91 | ; ClearSegmentsForBoot
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| 92 | ; Parameters:
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| 93 | ; Nothing
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| 94 | ; Returns:
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| 95 | ; DX: Zero
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| 96 | ; DS=ES: Zero
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| 97 | ; Corrupts registers:
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| 98 | ; Nothing
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| 99 | ;--------------------------------------------------------------------
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| 100 | ALIGN JUMP_ALIGN
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| 101 | ClearSegmentsForBoot:
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| 102 | xor dx, dx ; Device supported by INT 13h
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| 103 | mov ds, dx
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| 104 | mov es, dx
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| 105 | ret
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