source: xtideuniversalbios/trunk/XTIDE_Universal_BIOS/Src/Boot/BootMenuInfo.asm @ 254

; Project name  :   XTIDE Universal BIOS
; Description   :   Functions for generating and accessing drive
;                   information to be displayed on boot menu.

; Section containing code
SECTION .text

;--------------------------------------------------------------------
; Creates new BOOTMENUINFO struct for detected hard disk.
;
; BootMenuInfo_CreateForHardDisk
;   Parameters:
;       DL:     Drive number
;       DS:DI:  Ptr to Disk Parameter Table
;       ES:SI:  Ptr to 512-byte ATA information read from the drive
;   Returns:
;       ES:BX:  Ptr to BOOTMENUINFO (if successful)
;   Corrupts registers:
;       AX, BX, CX, DX, DI
;--------------------------------------------------------------------
BootMenuInfo_CreateForHardDisk:
    call    BootMenuInfo_ConvertDPTtoBX         ; ES:BX now points to new BOOTMENUINFO
    push    bx                                  ; Preserve for return

    mov     di, bx                              ; Starting pointer at beginning of structure

    ; Store Drive Name
    push    ds                                  ; Preserve RAMVARS
    push    si

    push    es                                  ; ES copied to DS
    pop     ds

    add     si, BYTE ATA1.strModel              ; DS:SI now points drive name
    lea     di, [bx+BOOTMENUINFO.szDrvName]     ; ES:DI now points to name destination
    mov     cx, MAX_HARD_DISK_NAME_LENGTH / 2   ; Max number of WORDs allowed
.CopyNextWord:
    lodsw
    xchg    al, ah                              ; Change endianness
    stosw
    loop    .CopyNextWord
    xor     ax, ax                              ; Zero AX and clear CF
    stosw                                       ; Terminate with NULL

    pop     si
    pop     ds
    pop     bx
        
    ret


;--------------------------------------------------------------------
; BootMenuInfo_GetTotalSectorCount
;   Parameters:
;       DS:DI:      DPT Pointer
;   Returns:
;       BX:DX:AX:   48-bit sector count
;   Corrupts registers:
;       CX
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
BootMenuInfo_GetTotalSectorCount:
    test    BYTE [di+DPT.bFlagsLow], FLG_DRVNHEAD_LBA
    jnz     SHORT .ReturnFullCapacity
    jmp     AH15h_GetSectorCountToBXDXAX
.ReturnFullCapacity:
    jmp     AccessDPT_GetLbaSectorCountToBXDXAX


;--------------------------------------------------------------------
; Returns offset to BOOTMENUINFO based on DPT pointer.
;
; BootMenuInfo_ConvertDPTtoBX
;   Parameters:
;       DS:DI:  DPT Pointer
;   Returns:
;       BX:     Offset to BOOTMENUINFO struct
;   Corrupts registers:
;       AX
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
BootMenuInfo_ConvertDPTtoBX:
    mov     ax, di
    sub     ax, RAMVARS_size                        ; subtract off base of DPTs
    mov     bl, DPT_BOOTMENUINFO_SIZE_MULTIPLIER    ; BOOTMENUINFO's are a whole number multiple of DPT size
    mul     bl                              
    add     ax, BOOTVARS.rgBootNfo                  ; add base of BOOTMENUINFO
    xchg    ax, bx
    ret