source: xtideuniversalbios/trunk/Assembly_Library/Src/Util/Size.asm@ 605

; Project name  :   Assembly Library
; Description   :   Functions for size calculations.

;
; XTIDE Universal BIOS and Associated Tools
; Copyright (C) 2009-2010 by Tomi Tilli, 2011-2013 by XTIDE Universal BIOS Team.
;
; This program is free software; you can redistribute it and/or modify
; it under the terms of the GNU General Public License as published by
; the Free Software Foundation; either version 2 of the License, or
; (at your option) any later version.
;
; This program is distributed in the hope that it will be useful,
; but WITHOUT ANY WARRANTY; without even the implied warranty of
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
; GNU General Public License for more details.
; Visit http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
;

%ifdef INCLUDE_MENU_LIBRARY
struc BYTE_MULTIPLES
    .B          resb    1
    .kiB        resb    1
    .MiB        resb    1
    .GiB        resb    1
    .TiB        resb    1
endstruc

; Section containing code
SECTION .text

;--------------------------------------------------------------------
; Size_GetSizeToAXAndCharToDLfromBXDXAXwithMagnitudeInCX
;   Parameters:
;       BX:DX:AX:   Size in magnitude
;       CX:         Magnitude in BYTE_MULTIPLES
;   Returns:
;       AX:         Size in magnitude
;       CX:         Tenths
;       DL:         Magnitude character:
;                       'k' = *1024   B = kiB
;                       'M' = *1024 kiB = MiB
;                       'G' = *1024 MiB = GiB
;                       'T' = *1024 GiB = TiB
;                       'P' = *1024 TiB = PiB
;   Corrupts registers:
;       BX, DH
;--------------------------------------------------------------------
ALIGN UTIL_SIZE_JUMP_ALIGN
Size_GetSizeToAXAndCharToDLfromBXDXAXwithMagnitudeInCX:
%ifndef USE_186     ; If 8086/8088
    push    di
%endif
    push    si

ALIGN UTIL_SIZE_JUMP_ALIGN
.MagnitudeConversionLoop:
    ePUSH_T di, .MagnitudeConversionLoop; DI corrupted only on 8086/8088 build
%ifdef USE_186
    test    bx, bx                      ; Bits 32...47 in use?
    jnz     SHORT Size_DivideSizeInBXDXAXby1024andIncrementMagnitudeInCX
    test    dx, dx                      ; Bits 16...31 in use?
    jnz     SHORT Size_DivideSizeInBXDXAXby1024andIncrementMagnitudeInCX
%else ; 808x
    mov     di, bx
    or      di, dx
    jnz     SHORT Size_DivideSizeInBXDXAXby1024andIncrementMagnitudeInCX
%endif
    cmp     ax, 10000                   ; 5 digits needed?
    jae     SHORT Size_DivideSizeInBXDXAXby1024andIncrementMagnitudeInCX
    add     sp, BYTE 2                  ; Clean return address from stack

    ; Convert remainder to tenths
    mov     bx, 640
    xchg    bx, ax                      ; BX = Size, AX = (10 / 1024) * 65536
    mul     si                          ; DX = Remainder * (10 / 1024)
    xchg    dx, ax
    xchg    cx, ax                      ; CX = Tenths, AX = Magnitude
    xchg    bx, ax                      ; AX = Size, BX = Magnitude

    ; Convert magnitude to character
    mov     dl, [cs:bx+.rgbMagnitudeToChar]

    pop     si
%ifndef USE_186
    pop     di
%endif
    ret
.rgbMagnitudeToChar:    db  " kMGTP"

;--------------------------------------------------------------------
; Size_DivideSizeInBXDXAXby1024andIncrementMagnitudeInCX
;   Parameters:
;       BX:DX:AX:   Size
;       CX:         Magnitude in BYTE_MULTIPLES (must be 254 or less)
;   Returns:
;       BX:DX:AX:   Size in magnitude
;       SI:         Remainder (0...1023)
;       CX:         Magnitude in BYTE_MULTIPLES
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
ALIGN UTIL_SIZE_JUMP_ALIGN
Size_DivideSizeInBXDXAXby1024andIncrementMagnitudeInCX:
    inc     cx                      ; Increment magnitude
    mov     si, 1023
    and     si, ax                  ; Remainder now in SI
    ; Fall to Size_DivideSizeInBXDXAXby1024
%endif ; INCLUDE_MENU_LIBRARY

;--------------------------------------------------------------------
; Size_DivideSizeInBXDXAXby1024
;   Parameters:
;       BX:DX:AX:   Size
;       CX:         Must be 255 or less
;   Returns:
;       BX:DX:AX:   Size divided by 1024
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
ALIGN UTIL_SIZE_JUMP_ALIGN
Size_DivideSizeInBXDXAXby1024:
%ifdef USE_386
    shrd    ax, dx, 10
    shrd    dx, bx, 10
    shr     bx, 10
%else
    push    cx
    mov     cl, 10
ALIGN UTIL_SIZE_JUMP_ALIGN
.ShiftLoop:
    call    Size_DivideBXDXAXbyTwo
    loop    .ShiftLoop
    pop     cx
%endif
    ret

;--------------------------------------------------------------------
; Size_ConvertSectorCountInBXDXAXtoKiB
; Size_DivideBXDXAXbyTwo
;   Parameters:
;       BX:DX:AX:   Total sector count
;   Returns:
;       BX:DX:AX:   Total size in kiB
;       CF:         Remainder from division
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
%ifdef EXCLUDE_FROM_XUB
    %ifdef USE_386
        %define EXCLUDE
    %endif
    %ifdef MODULE_BOOT_MENU
        %undef EXCLUDE
    %endif
%endif

%ifndef EXCLUDE
ALIGN UTIL_SIZE_JUMP_ALIGN
Size_ConvertSectorCountInBXDXAXtoKiB:   ; unused entrypoint ok
Size_DivideBXDXAXbyTwo:                 ; unused entrypoint ok
    shr     bx, 1                   ; Divide sector count by 2...
    rcr     dx, 1                   ; ...to get disk size in...
    rcr     ax, 1                   ; ...kiB
    ret
%endif
%undef EXCLUDE