193 lines
4.6 KiB
NASM
193 lines
4.6 KiB
NASM
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page ,132
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subttl emspec.asm - Special emulator functions for speed
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;***
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;emspec.asm - Special emulator functions for speed
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;
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; Copyright (c) 1987-89, Microsoft Corporation
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;
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;Purpose:
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; Special emulator functions for speed
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;
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; This Module contains Proprietary Information of Microsoft
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; Corporation and should be treated as Confidential.
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;
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;Revision History:
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; See emulator.hst
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;
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;*******************************************************************************
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ProfBegin SPEC
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pub loadcontrolword
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ifdef QB3
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or al,2 ; mask denormal exceptions
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endif ;QB3
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mov [UserControlWord],ax ; save user's version
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and ax,0FF3CH ; Turn off reserved, IEM, Denormal
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; & invalid exception mask bits
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ifndef frontend
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ifndef only87
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cmp [Have8087],0 ; Non-0 if 8087 present
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je EmulateFLDCW
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endif ;only87
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mov [REMLSW],ax ; use this cell (not busy)
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fnop ; fix for intel erratum #8
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fldcw [REMLSW] ; 8087 gets new control word
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endif ;frontend
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pub EmulateFLDCW
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mov [ControlWord],ax ; save internal control word
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ret
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;-----------------------------------------------------------------------------
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ifndef QB3 ; rest not needed if QB 3
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pub storecontrolword
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mov ax,[UserControlWord] ; get user's version
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ret
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pub storestatusword
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xor ax,ax
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ifndef frontend
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cmp al,[Have8087]
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je no87status
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fstsw [NewStatusWord]
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fwait
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mov al,byte ptr [NewStatusWord] ; get exception summary
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and al,03Fh ; only low 6 bits are wanted
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endif ;frontend
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pub no87status
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or ax,[UserStatusWord] ; or with full status
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and ax,UStatMask ; mask down to actual status bits
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mov [UserStatusWord],ax ; update full status word
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ret
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page
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; Procedure to truncate TOS to integer TOS
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; ax = new rounding control
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pub truncateTOS
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and ax,RoundControl shl 8 ; mask to new rounding control
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ifndef frontend
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ifndef only87
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cmp [Have8087],0
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je Emulatetruncate
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endif ;only87
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FSTCW [ControlWord] ; get control word
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FWAIT ; synchronize
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MOV CX,[ControlWord] ; round mode saved
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and ch,not RoundControl ; clear rounding control bits
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OR ax,cx ; set new rounding
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MOV [REMLSW],AX ; back to memory
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FLDCW [REMLSW] ; reset rounding
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FRNDINT ; "round" top of stack
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FLDCW [ControlWord] ; restore rounding
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RET ; simple return
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endif ;frontend
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ifndef only87
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pub Emulatetruncate
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mov cx,[ControlWord]
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push cx ; remember what control word was
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and ch,not RoundControl ; clear rounding control bits
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OR ah,ch ; set new rounding
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MOV [CWcntl],ah ; flag new rounding mode
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PUSH BP ; save BP
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CALL eFRNDINT
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POP BP ; restore BP
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POP [ControlWord] ; set back to the way it was
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call checktrunc ; check for truncation error
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RET ; finished
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endif ;only87
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page
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; Procedure to truncate TOS to integer in DX:AX
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; ax = new rounding control
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pub truncateTOSto32int
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and ax,RoundControl shl 8
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ifndef frontend
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ifndef only87
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cmp [Have8087],0
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je Emulatetruncateto32int
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endif ;only87
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FSTCW [ControlWord] ; get control word
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FWAIT ; synchronize
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MOV CX,[ControlWord] ; round mode saved
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and ch,not RoundControl ; clear rounding control bits
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OR ax,cx ; set new rounding
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MOV [REMLSW],AX ; back to memory
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FLDCW [REMLSW] ; reset rounding
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FISTP dword ptr [REMLSW] ; "round" top of stack
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FLDCW [ControlWord] ; restore rounding
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mov ax,[REMLSW]
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mov dx,[REMLSW+2]
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RET ; simple return
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endif ;frontend
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ifndef only87
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pub Emulatetruncateto32int
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mov cx,[ControlWord]
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push cx ; remember what control word was
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and ch,not RoundControl ; clear rounding control bits
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OR ah,ch ; set new rounding
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MOV [CWcntl],ah ; flag new rounding mode
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PUSH BP ; save BP
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CALL TOSto32int ; convert to 32-bit int in BX:DX
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POP BP ; restore BP
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mov ax,dx
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mov dx,bx
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call checktrunc ; check for truncation error
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POPST ; pop of current stack entry
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POP [ControlWord] ; set back to the way it was
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pub truncerrOK ; (reuse RET for routine below)
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RET ; finished
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; check for errors
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pub checktrunc ; !!! check emmain for same code
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MOV cx,[CURerr] ; fetch errors
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or [UserStatusWord],cx ; OR into user status word
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OR [SWerr],cl ; set errors in sticky error flag
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NOT cl ; make a zero mean an error
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MOV ch,byte ptr [UserControlWord] ; get user's IEEE control word
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OR ch,0C2H ; mask reserved, IEM and denormal bits
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AND ch,03FH ; unmask invalid instruction,
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; stack overflow.
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OR cl,ch ; mask for IEEE exceptions
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NOT cl ; make a one mean an error
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MOV ch,byte ptr (CURerr+1) ; get stack over/underflow flags
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TEST cx,0FFFFh-MemoryOperand ; test for errors to report
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jz truncerrOK ; error is masked
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xchg ax,cx ; ax = exception
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jmp CommonExceptions ; handle error (??? unclean stack)
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endif ;only87
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endif ;QB3
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ProfEnd SPEC
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