source: xtideuniversalbios/trunk/Assembly_Library/Src/Util/Registers.asm@ 61

; File name     :   Registers.asm
; Project name  :   Assembly Library
; Created date  :   24.10.2010
; Last update   :   24.10.2010
; Author        :   Tomi Tilli
; Description   :   Functions for register operations.

; Section containing code
SECTION .text

;--------------------------------------------------------------------
; Registers_ExchangeDSSIwithESDI
;   Parameters
;       Nothing
;   Returns:
;       DS:SI and ES:DI are exchanged.
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
Registers_ExchangeDSSIwithESDI:
    push    ds
    push    es
    pop     ds
    pop     es
    xchg    si, di
    ret


;--------------------------------------------------------------------
; Registers_CopySSBPtoESDI
; Registers_CopySSBPtoDSSI
; Registers_CopyDSSItoESDI
; Registers_CopyESDItoDSSI
;   Parameters
;       Nothing
;   Returns:
;       Copies farm pointer to different segment/pointer register pair
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
Registers_CopySSBPtoESDI:
    push    ss
    pop     es
    mov     di, bp
    ret

ALIGN JUMP_ALIGN
Registers_CopySSBPtoDSSI:
    push    ss
    pop     ds
    mov     si, bp
    ret

ALIGN JUMP_ALIGN
Registers_CopyDSSItoESDI:
    push    ds
    pop     es
    mov     di, si
    ret

ALIGN JUMP_ALIGN
Registers_CopyESDItoDSSI:
    push    es
    pop     ds
    mov     si, di
    ret


;--------------------------------------------------------------------
; Registers_SetZFifNullPointerInDSSI
;   Parameters
;       DS:SI:  Far pointer
;   Returns:
;       ZF:     Set if NULL pointer in DS:SI
;   Corrupts registers:
;       Nothing
;--------------------------------------------------------------------
ALIGN JUMP_ALIGN
Registers_SetZFifNullPointerInDSSI:
    push    ax
    mov     ax, ds
    or      ax, si
    pop     ax
    ret