subttl    emstack.asm - Emulator Stack Management Macros
    page
;***
;emstack.asm - Emulator Stack Management Area

;     Microsoft Confidential
;     Copyright (c) Microsoft Corporation 1991
;     All Rights Reserved

;Purpose:
;    Handles emulator stack.

;Revision History:

; []    09/05/91  TP    Initial 32-bit version.

;*******************************************************************************


;POPSTret:  pops the stack and returns.  Uses esi.

POPSTret        macro    reg
        local   stackwrap
IFB    <reg>
        mov     esi,EMSEG:[CURstk]
_popreg    equ    esi
ELSE
_popreg    equ    reg
ENDIF
    mov     EMSEG:[_popreg].bTag,bTAG_EMPTY
        NextStackElem   _popreg,stackwrap
        mov     EMSEG:[CURstk],_popreg
        ret

Wrap&stackwrap:
    mov    EMSEG:[CURstk],BEGstk
    ret
    endm

;NextStackElem:  Given pST(0) = [CURstk] in reg, returns pST(1)
;Requires NextStackWrap macro with same arguments

NextStackElem    macro    reg,stackwrap
    cmp    reg,INITstk            ;JWM
    jae    Wrap&stackwrap
    add    reg,Reg87Len
Cont&stackwrap:
    endm

NextStackWrap    macro    reg,stackwrap
Wrap&stackwrap:
    mov    reg,BEGstk            ;JWM
    jmp    Cont&stackwrap
    endm


;PrevStackElem:  Given pST(0) = [CURstk] in reg, returns new pST(0)
;after a push onto on the stack.
;Requires PrevStackWrap macro with same arguments

PrevStackElem    macro    reg,stackwrap
    cmp    reg,BEGstk            ;JWM
    jbe    Wrap&stackwrap
    sub    reg,Reg87Len
Cont&stackwrap:
    endm

PrevStackWrap    macro    reg,stackwrap
Wrap&stackwrap:
    mov    reg,INITstk            ;JWM
    jmp    Cont&stackwrap
    endm