[88] | 1 | ; Project name : XTIDE Universal BIOS |
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[3] | 2 | ; Description : Defines for BOOTVARS struct used by boot menu |
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| 3 | ; and drive initialization. |
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| 4 | %ifndef BOOTVARS_INC |
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| 5 | %define BOOTVARS_INC |
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| 6 | |
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| 7 | |
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[96] | 8 | BOOT_READ_RETRY_TIMES EQU 3 |
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| 9 | |
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| 10 | |
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[3] | 11 | ; Boot Menu Information Table. These are generated for all XTIDE Universal |
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| 12 | ; BIOS drives. Available only until boot is successfull. |
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| 13 | LEN_BOOTNFO_DRV EQU 26 ; Bytes reserved for drive name |
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| 14 | struc BOOTNFO |
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| 15 | .twSectCnt resb 6 ; Total user addressable sectors |
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| 16 | .szDrvName resb LEN_BOOTNFO_DRV+1 ; Drive name |
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| 17 | resb 1 ; Alignment |
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| 18 | endstruc |
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| 19 | |
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| 20 | |
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| 21 | ; Pre-boot variables. These do not exist after successfull boot to OS. |
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| 22 | ; Segment is always 0000h, same as BDA segment |
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| 23 | struc BOOTVARS |
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| 24 | resb 800h |
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| 25 | .dwPostStack resb 4 ; 804h, POST stack when entering INT 19h |
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[90] | 26 | resb 8 |
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[3] | 27 | .rgBootNfo resb 73F4h ; 80Ch, Array containing BOOTNFO structs |
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| 28 | .rgbMnuStack: ; 7C00h and below, Boot Menu stack |
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| 29 | .rgbAtaInfo: ; 7C00h, ATA Information for drive detection |
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| 30 | .rgbBootSect resb 512 ; 7C00h, Boot sector |
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| 31 | endstruc |
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| 32 | |
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| 33 | |
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[121] | 34 | ;-------------------------------------------------------------------- |
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| 35 | ; Stores POST stack pointer to BOOTVARS. |
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| 36 | ; |
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| 37 | ; STORE_POST_STACK_POINTER |
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| 38 | ; Parameters: |
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| 39 | ; DS: BDA and Interrupt Vector segment (zero) |
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| 40 | ; Returns: |
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| 41 | ; Nothing |
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| 42 | ; Corrupts registers: |
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| 43 | ; Nothing |
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| 44 | ;-------------------------------------------------------------------- |
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| 45 | %macro STORE_POST_STACK_POINTER 0 |
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| 46 | mov [BOOTVARS.dwPostStack], sp |
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| 47 | mov [BOOTVARS.dwPostStack+2], ss |
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| 48 | %endmacro |
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| 49 | |
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| 50 | |
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| 51 | ;-------------------------------------------------------------------- |
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| 52 | ; Initializes stack for boot menu usage. |
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| 53 | ; POST stack is not large enough when DPTs are stored to 30:0h. |
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| 54 | ; |
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| 55 | ; Note regarding LOAD_BDA_SEGMENT_TO: If you force the use of SP |
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| 56 | ; then you also have to unconditionally enable the CLI/STI pair. |
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| 57 | ; The reason for this is that only some buggy 808x CPU:s need the |
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| 58 | ; CLI/STI instruction pair when changing stacks. Other CPU:s disable |
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| 59 | ; interrupts automatically when SS is modified for the duration of |
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| 60 | ; the immediately following instruction to give time to change SP. |
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| 61 | ; |
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| 62 | ; SWITCH_TO_BOOT_MENU_STACK |
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| 63 | ; Parameters: |
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| 64 | ; Nothing |
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| 65 | ; Returns: |
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| 66 | ; SS:SP: Pointer to top of Boot Menu stack |
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| 67 | ; Corrupts registers: |
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| 68 | ; Nothing |
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| 69 | ;-------------------------------------------------------------------- |
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| 70 | %macro SWITCH_TO_BOOT_MENU_STACK 0 |
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| 71 | %ifndef USE_186 |
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| 72 | cli ; Disable interrupts |
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| 73 | %endif |
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| 74 | LOAD_BDA_SEGMENT_TO ss, sp |
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| 75 | mov sp, BOOTVARS.rgbMnuStack ; Load offset to stack |
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| 76 | %ifndef USE_186 |
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| 77 | sti ; Enable interrupts |
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| 78 | %endif |
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| 79 | %endmacro |
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| 80 | |
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| 81 | |
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| 82 | ;-------------------------------------------------------------------- |
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| 83 | ; Restores SS and SP to initial boot loader values. |
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| 84 | ; |
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| 85 | ; Before doing any changes, see the note regarding |
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| 86 | ; LOAD_BDA_SEGMENT_TO in BootVars_SwitchToBootMenuStack |
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| 87 | ; |
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| 88 | ; SWITCH_BACK_TO_POST_STACK |
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| 89 | ; Parameters: |
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| 90 | ; Nothing |
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| 91 | ; Returns: |
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| 92 | ; SS:SP: Ptr to POST stack |
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| 93 | ; Corrupts registers: |
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| 94 | ; Nothing |
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| 95 | ;-------------------------------------------------------------------- |
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| 96 | %macro SWITCH_BACK_TO_POST_STACK 0 |
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| 97 | %ifndef USE_386 |
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| 98 | cli ; Disable interrupts |
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| 99 | LOAD_BDA_SEGMENT_TO ss, sp |
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| 100 | mov sp, [ss:BOOTVARS.dwPostStack] |
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| 101 | mov ss, [ss:BOOTVARS.dwPostStack+2] |
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| 102 | sti ; Enable interrupts |
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| 103 | %else |
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| 104 | LOAD_BDA_SEGMENT_TO ss, sp |
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| 105 | lss sp, [ss:BOOTVARS.dwPostStack] |
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| 106 | %endif |
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| 107 | %endmacro |
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| 108 | |
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| 109 | |
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[3] | 110 | %endif ; BOOTVARS_INC |
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