source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/Boot/BootInfo.asm@ 244

Last change on this file since 244 was 241, checked in by gregli@…, 13 years ago

Space optimizations in the Boot Menu and BootInfo routines, taking advantage of nested %s. Optimization in the init of RamVars to avoid writing the signature twice. Preparing for addition of serial floppy support, starting to break the assumption that our drives are always 80h or higher.

File size: 2.8 KB
RevLine 
[88]1; Project name : XTIDE Universal BIOS
[3]2; Description : Functions for generating and accessing drive
3; information to be displayed on boot menu.
4
5; Section containing code
6SECTION .text
7
8;--------------------------------------------------------------------
9; Creates new BOOTNFO struct for detected hard disk.
10;
11; BootInfo_CreateForHardDisk
12; Parameters:
13; DL: Drive number
14; DS:DI: Ptr to Disk Parameter Table
15; ES:SI: Ptr to 512-byte ATA information read from the drive
16; Returns:
17; ES:BX: Ptr to BOOTNFO (if successful)
18; Corrupts registers:
[241]19; AX, BX, CX, DX, DI, SI
[3]20;--------------------------------------------------------------------
21BootInfo_CreateForHardDisk:
[241]22 call BootInfo_ConvertDPTtoBX ; ES:BX now points to new BOOTNFO
23 push bx ; Preserve for return
[3]24
[241]25 mov di, bx ; Starting pointer at beginning of structure
[3]26
[241]27;
28; Store Drive Name
29;
30 push ds ; Preserve RAMVARS
31 push si ; Preserve SI for call to GetTotalSectorCount...
[3]32
[241]33 push es ; ES copied to DS
[3]34 pop ds
[241]35
[100]36 add si, BYTE ATA1.strModel ; DS:SI now points drive name
37 lea di, [bx+BOOTNFO.szDrvName] ; ES:DI now points to name destination
[121]38 mov cx, LEN_BOOTNFO_DRV / 2 ; Max number of WORDs allowed
39.CopyNextWord:
40 lodsw
41 xchg al, ah ; Change endianness
42 stosw
43 loop .CopyNextWord
[128]44 xor ax, ax ; Zero AX and clear CF
[241]45 stosw ; Terminate with NULL
[3]46
47 pop si
48 pop ds
[241]49
50;
51; Store Sector Count
52;
53 call AtaID_GetTotalSectorCountToBXDXAXfromAtaInfoInESSI
54
55 stosw
56 xchg ax, dx
57 stosw
58 xchg ax, bx
59 stosw
60
61 pop bx
62
[3]63 ret
64
[241]65
[3]66;--------------------------------------------------------------------
[100]67; Finds BOOTNFO for drive and returns total sector count.
[3]68;
69; BootInfo_GetTotalSectorCount
70; Parameters:
[241]71; DS:DI: DPT Pointer
[3]72; Returns:
73; BX:DX:AX: 48-bit sector count
74; Corrupts registers:
75; Nothing
[128]76;--------------------------------------------------------------------
[3]77ALIGN JUMP_ALIGN
78BootInfo_GetTotalSectorCount:
79 push ds
[241]80 call BootInfo_ConvertDPTtoBX
[3]81 LOAD_BDA_SEGMENT_TO ds, ax
82 mov ax, [bx+BOOTNFO.twSectCnt]
83 mov dx, [bx+BOOTNFO.twSectCnt+2]
84 mov bx, [bx+BOOTNFO.twSectCnt+4]
85 pop ds
86 ret
[100]87
88
89;--------------------------------------------------------------------
[241]90; Returns offset to BOOTNFO based on DPT pointer.
[100]91;
[241]92; BootInfo_ConvertDPTtoBX
[100]93; Parameters:
[241]94; DS:DI: DPT Pointer
[100]95; Returns:
96; BX: Offset to BOOTNFO struct
97; Corrupts registers:
98; AX
99;--------------------------------------------------------------------
100ALIGN JUMP_ALIGN
[241]101BootInfo_ConvertDPTtoBX:
102 mov ax, di
103 sub ax, RAMVARS_size ; subtract off base of DPTs
104 mov bl, DPT_BOOTNFO_SIZE_MULTIPLIER ; BOOTNFO's are a whole number multiple of DPT size
105 mul bl
106 add ax, BOOTVARS.rgBootNfo ; add base of BOOTNFO
107 xchg ax, bx
108 ret
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