Changeset 173 in xtideuniversalbios for trunk/XTIDE_Universal_BIOS/Src/Initialization


Ignore:
Timestamp:
Sep 18, 2011, 11:41:29 AM (13 years ago)
Author:
aitotat@…
google:author:
aitotat@gmail.com
Message:

Changes to XTIDE Universal BIOS:

  • L-CHS parameters are now generated differently for LBA enabled drives.
  • Booting to EBIOS partitions now seems to work (at least on one drive).
File:
1 edited

Legend:

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  • trunk/XTIDE_Universal_BIOS/Src/Initialization/AtaID.asm

    r169 r173  
    55; Section containing code
    66SECTION .text
     7
     8;--------------------------------------------------------------------
     9; LBA assist calculation:
     10; this is how to fit a big drive into INT13's skimpy size requirements,
     11; with a maximum of 8.4G available.
     12;
     13; total LBAs (as obtained by words 60+61)
     14; divided by 63 (sectors per track) (save as value A)
     15; Sub 1 from A
     16; divide A by 1024 + truncate.
     17; == total number of heads to use.
     18; add 1
     19; this value must be either 16, 32, 64, 128, or 256 (round up)
     20; then take the value A above and divide by # of heads
     21; to get the # of cylinders to use. 
     22;
     23;
     24; so a LBA28 drive will have 268,435,456 as maximum LBAs
     25;
     26; 10000000h / 63   = 410410h (total cylinders or tracks)
     27;   410410h / 1024 = 1041h, which is way more than 256 heads, but 256 is max.
     28;   410410h / 256  = 4104h cylinders
     29;
     30; there's a wealth of information at: http://www.mossywell.com/boot-sequence
     31; they show a slightly different approach to LBA assist calulations, but
     32; the method here provides compatibility with phoenix BIOS
     33;
     34; we're using the values from 60+61 here because we're topping out at 8.4G
     35; anyway, so there's no need to use the 48bit LBA values.
     36;
     37; AtaID_GetLbaAssistedCHStoAXBLBH:
     38;   Parameters:
     39;       BX:DX:AX:   Total number of sectors
     40;   Returns:
     41;       DX:AX:  Number of cylinders
     42;       BH:     Number of sectors per track (always 63)
     43;       BL:     Number of heads (16, 32, 64, 128 or 255)
     44;   Corrupts registers:
     45;       CX
     46;--------------------------------------------------------------------
     47AtaID_GetLbaAssistedCHStoDXAXBLBH:
     48    push    bp
     49    push    si
     50
     51    ; Value A = Total sector count / 63
     52    xor     cx, cx
     53    push    cx      ; Push zero for bits 48...63
     54    push    bx
     55    push    dx
     56    push    ax                      ; 64-bit sector count now in stack
     57    mov     cl, LBA_ASSIST_SPT
     58    mov     bp, sp                  ; SS:BP now points sector count
     59    call    Math_DivQWatSSBPbyCX    ; Temporary value A now in stack
     60
     61    ; BX = Number of heads =  A / 1024
     62    mov     ax, [bp]
     63    mov     dx, [bp+2]
     64    mov     bx, [bp+4]
     65    call    Size_DivideSizeInBXDXAXby1024andIncrementMagnitudeInCX
     66
     67    ; Heads must be 16, 32, 64, 128 or 256 (round up)
     68    mov     bx, 256                     ; Max number of heads
     69    test    dx, dx                      ; 65536 or more heads?
     70    jnz     SHORT .GetNumberOfCylinders
     71    mov     cx, 128                     ; Half BX for rounding up
     72.FindMostSignificantBitForHeadSize:
     73    cmp     ax, cx
     74    jae     SHORT .GetNumberOfCylinders
     75    shr     cx, 1
     76    shr     bx, 1                       ; Halve number of heads
     77    jmp     SHORT .FindMostSignificantBitForHeadSize
     78
     79    ; DX:AX = Number of cylinders = A / number of heads
     80.GetNumberOfCylinders:
     81    mov     cx, bx
     82    call    Math_DivQWatSSBPbyCX
     83    mov     ax, [bp]
     84    mov     dx, [bp+2]                  ; Cylinders now in DX:AX
     85
     86    ; Return LBA assisted CHS
     87    add     sp, BYTE 8                  ; Clean stack
     88    sub     bl, bh                      ; Limit heads to 255
     89    mov     bh, LBA_ASSIST_SPT
     90    pop     si
     91    pop     bp
     92    ret
     93
    794
    895;--------------------------------------------------------------------
    … …  
    34121;--------------------------------------------------------------------
    35122AtaID_GetTotalSectorCountToBXDXAXfromAtaInfoInESSI:
    36     push    ds
    37 
    38     push    es
    39     pop     ds
     123    call    Registers_ExchangeDSSIwithESDI  ; ATA info now in DSDI
    40124    xor     bx, bx
    41     test    WORD [si+ATA1.wCaps], A1_wCaps_LBA
     125    test    BYTE [di+ATA1.wCaps+1], A1_wCaps_LBA>>8
    42126    jz      SHORT .GetChsSectorCount
    43127    ; Fall to .GetLbaSectorCount
    … …  
    45129;--------------------------------------------------------------------
    46130; .GetLbaSectorCount
     131; .GetLba28SectorCount
     132; .GetChsSectorCount
    47133;   Parameters:
    48134;       BX:     Zero
    … …  
    54140;--------------------------------------------------------------------
    55141.GetLbaSectorCount:
    56     test    WORD [si+ATA6.wSetSup83], A6_wSetSup83_LBA48
     142    test    BYTE [di+ATA6.wSetSup83+1], A6_wSetSup83_LBA48>>8
    57143    jz      SHORT .GetLba28SectorCount
    58     mov     ax, [si+ATA6.qwLBACnt]
    59     mov     dx, [si+ATA6.qwLBACnt+2]
    60     mov     bx, [si+ATA6.qwLBACnt+4]
    61     pop     ds
    62     ret
     144    mov     ax, [di+ATA6.qwLBACnt]
     145    mov     dx, [di+ATA6.qwLBACnt+2]
     146    mov     bx, [di+ATA6.qwLBACnt+4]
     147    jmp     SHORT .ExchangePtrAndReturn
     148
    63149.GetLba28SectorCount:
    64     mov     ax, [si+ATA1.dwLBACnt]
    65     mov     dx, [si+ATA1.dwLBACnt+2]
    66     pop     ds
    67     ret
     150    mov     ax, [di+ATA1.dwLBACnt]
     151    mov     dx, [di+ATA1.dwLBACnt+2]
     152    jmp     SHORT .ExchangePtrAndReturn
    68153
    69 ;--------------------------------------------------------------------
    70 ; .GetChsSectorCount
    71 ;   Parameters:
    72 ;       DS:SI:  Ptr to 512-byte ATA information read from the drive
    73 ;   Returns:
    74 ;       DX:AX:  24-bit sector count
    75 ;   Corrupts registers:
    76 ;       Nothing
    77 ;--------------------------------------------------------------------
    78154.GetChsSectorCount:
    79     mov     al, [si+ATA1.wSPT]      ; AL=Sectors per track
    80     mul     BYTE [si+ATA1.wHeadCnt] ; AX=Sectors per track * number of heads
    81     mul     WORD [si+ATA1.wCylCnt]  ; DX:AX=Sectors per track * number of heads * number of cylinders
    82     pop     ds
    83     ret
     155    mov     al, [di+ATA1.wSPT]      ; AL=Sectors per track
     156    mul     BYTE [di+ATA1.wHeadCnt] ; AX=Sectors per track * number of heads
     157    mul     WORD [di+ATA1.wCylCnt]  ; DX:AX=Sectors per track * number of heads * number of cylinders
     158.ExchangePtrAndReturn:
     159    jmp     Registers_ExchangeDSSIwithESDI
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