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subttl emfmisc.asm - FABS, FCHS, FFREE, FXCH
page
;*******************************************************************************
;emfmisc.asm - FABS, FCHS, FFREE, FXCH
;
; Microsoft Confidential
;
; Copyright (c) Microsoft Corporation 1991
; All Rights Reserved
;
;Purpose:
; FABS, FCHS, FFREE, FXCH instructions
;Inputs:
; edi = [CURstk]
; esi = pointer to st(i) from instruction field
;
;Revision History:
;
; [] 09/05/91 TP Initial 32-bit version.
;
;*******************************************************************************
;******
EM_ENTRY eFABS
eFABS:
;******
cmp EMSEG:[edi].bTag,bTAG_EMPTY
jz StackError ;in emarith.asm
mov EMSEG:[edi].bSgn,0 ;Turn sign bit off
ret
;******
EM_ENTRY eFCHS
eFCHS:
;******
cmp EMSEG:[edi].bTag,bTAG_EMPTY
jz StackError ;in emarith.asm
not EMSEG:[edi].bSgn ;Flip the sign
ret
;******
EM_ENTRY eFFREE
eFFREE:
;******
mov EMSEG:[esi].bTag,bTAG_EMPTY
ret
;******
EM_ENTRY eFXCH
eFXCH:
;******
cmp EMSEG:[esi].bTag,bTAG_EMPTY
jz XchDestEmpty
XchgChkSrc:
cmp EMSEG:[edi].bTag,bTAG_EMPTY
jz XchSrcEmpty
DoSwap:
;Swap [esi] with [edi]
mov eax,EMSEG:[edi]
xchg eax,EMSEG:[esi]
mov EMSEG:[edi],eax
mov eax,EMSEG:[edi+4]
xchg eax,EMSEG:[esi+4]
mov EMSEG:[edi+4],eax
mov eax,EMSEG:[edi+8]
xchg eax,EMSEG:[esi+8]
mov EMSEG:[edi+8],eax
ret
XchDestEmpty:
call ReturnIndefinite ;in emarith.asm - ZF set if unmasked
jnz XchgChkSrc ;Continue if masked
ret
XchSrcEmpty:
xchg edi,esi ;pass pointer in esi
call ReturnIndefinite ;in emarith.asm - ZF set if unmasked
xchg edi,esi
jnz DoSwap ;Continue if masked
ret
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