source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Inc/BootVars.inc @ 363

Last change on this file since 363 was 363, checked in by aitotat@…, 12 years ago

Changes to XTIDE Universal BIOS:

  • Added Advanced ATA Module (MODULE_ADVANCED_ATA) with native support for QDI Vision QD6500 and QD6580 VLB IDE Controllers.
  • Hopefully optimized IDE transfer functions for 8088 (replaced some memory accesses from WORD to BYTE).
  • XT build does not fit in 8k at the moment!!!
File size: 3.0 KB
Line 
1; Project name  :   XTIDE Universal BIOS
2; Description   :   Defines for BOOTVARS struct used by boot menu
3;                   and drive initialization.
4%ifndef BOOTVARS_INC
5%define BOOTVARS_INC
6
7
8BOOT_READ_RETRY_TIMES       EQU     3
9
10
11
12; Pre-boot variables. These do not exist after successful boot to OS.
13; Segment is always 0000h, same as BDA segment
14struc BOOTVARS
15                    resb    7C00h
16    .rgbAtaInfo:                    ; 7C00h, ATA Information for drive detection
17    .rgbBootSect    resb    512     ; 7C00h, Boot sector
18                    resb    256     ; Boot Menu stack
19    .rgbMnuStack:
20    .dwPostStack    resb    4       ; POST stack pointer when entering INT 19h
21    .wMagicWord     resb    2       ; I wish we didn't need this
22    .rgBootNfo:                     ; Array containing BOOTNFO structs
23endstruc
24
25; Magic WORD to detect when BOOTVARS is available.
26BOOTVARS_MAGIC_WORD         EQU     1110011001100111b
27
28
29
30;--------------------------------------------------------------------
31; Stores POST stack pointer to BOOTVARS.
32;
33; STORE_POST_STACK_POINTER
34;   Parameters:
35;       ES:     BDA and Interrupt Vector segment (zero)
36;   Returns:
37;       Nothing
38;   Corrupts registers:
39;       Nothing
40;--------------------------------------------------------------------
41%macro STORE_POST_STACK_POINTER 0
42    mov     [es:BOOTVARS.dwPostStack], sp
43    mov     [es:BOOTVARS.dwPostStack+2], ss
44%endmacro
45
46
47;--------------------------------------------------------------------
48; Initializes stack for boot menu usage.
49; POST stack is not large enough when DPTs are stored to 30:0h.
50;
51; Note regarding LOAD_BDA_SEGMENT_TO: If you force the use of SP
52; then you also have to unconditionally enable the CLI/STI pair.
53; The reason for this is that only some buggy 808x CPU:s need the
54; CLI/STI instruction pair when changing stacks. Other CPU:s disable
55; interrupts automatically when SS is modified for the duration of
56; the immediately following instruction to give time to change SP.
57;
58; SWITCH_TO_BOOT_MENU_STACK
59;   Parameters:
60;       Nothing
61;   Returns:
62;       SS:SP:  Pointer to top of Boot Menu stack
63;   Corrupts registers:
64;       Nothing
65;--------------------------------------------------------------------
66%macro SWITCH_TO_BOOT_MENU_STACK 0
67%ifndef USE_186
68    cli                                 ; Disable interrupts
69%endif
70    LOAD_BDA_SEGMENT_TO ss, sp
71    mov     sp, BOOTVARS.rgbMnuStack    ; Load offset to stack
72%ifndef USE_186
73    sti                                 ; Enable interrupts
74%endif
75%endmacro
76
77
78;--------------------------------------------------------------------
79; Restores SS and SP to initial boot loader values.
80;
81; Note! Must return with AX=0 and CF preserved.
82; See Int19hMenu_JumpToBootSector_or_RomBoot.
83;
84; SWITCH_BACK_TO_POST_STACK
85;   Parameters:
86;       AX:     BDA and Interrupt Vector segment (zero)
87;   Returns:
88;       SS:SP:  Ptr to POST stack
89;   Corrupts registers:
90;       Nothing (not even FLAGS)
91;--------------------------------------------------------------------
92%macro SWITCH_BACK_TO_POST_STACK 0
93%ifndef USE_386
94    cli
95    mov     ss, ax
96    mov     sp, [ss:BOOTVARS.dwPostStack]
97    mov     ss, [ss:BOOTVARS.dwPostStack+2]
98    sti
99%else
100    mov     ss, ax
101    lss     sp, [ss:BOOTVARS.dwPostStack]
102%endif
103%endmacro
104
105
106%endif ; BOOTVARS_INC
Note: See TracBrowser for help on using the repository browser.