286 lines
6 KiB
NASM
286 lines
6 KiB
NASM
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page ,132
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subttl emarith.asm - Arithmetic Operations
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;***
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;emarith.asm -
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;
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; Copyright (c) 1986-89, Microsoft Corporation
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;
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;Purpose:
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; Arithmetic Operations
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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: (Also see emulator.hst)
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;
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; 12/19/89 WAJ XORSIGN was not masking the sign bit correctly.
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;
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;*******************************************************************************
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;-----------------------------------------------;
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; ;
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; Double precision arithmetic ;
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; ;
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;-----------------------------------------------;
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; Inputs:
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; DI = (op1) NOS (Next on stack)
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; SI = (op2) TOS (Top of stack)
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;
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; Functions:
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; ADDRQQ - Addition RESULT <-- [DI] + [SI]
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; SUDRQQ - Subtract RESULT <-- [DI] - [SI]
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; MUDRQQ - Multiply RESULT <-- [DI] * [SI]
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; DIDRQQ - Division RESULT <-- [DI] / [SI]
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; SVDRQQ - Subtract Reversed RESULT <-- [SI] - [DI]
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; DRDRQQ - Division Reversed RESULT <-- [SI] / [DI]
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; Outputs:
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; Destination of result is in RESULT
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; Registers:
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; All except BP destroyed.
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; Understanding this code:
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;
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; Assign the symbol S to SI, assign the symbol D to DI.
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;
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; Upon entry: SI <-- S, DI <-- D , Performing D - S
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ProfBegin ARITH
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even
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lab SVDRQQ ; Reverse Subtract
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MOV DX,Sign*256 ; DH will be flag[SI], prepare to switch sign
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JMP short DOADD
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even
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lab SUDRQQ ; Normal Subtract
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MOV DX,Sign ; DL will be flag[DI], prepare to switch sign
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JMP short DOADD
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even
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lab MUDRQQ ; Multiplication
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xor idx,idx ; Do not change signs on entry
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MOV ibx,offset MULJMPTAB
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JMP short INITIL
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even
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lab DIDRQQ ; Normal Division
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xor idx,idx
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XCHG isi,idi ; Make SI - Numerator, DI - Denominator
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MOV ibx,offset DIVJMPTAB
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JMP short INITIL
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even
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lab DRDRQQ ; Reverse Division
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xor idx,idx
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MOV ibx,offset DIVJMPTAB
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JMP short INITIL
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even
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lab ADDRQQ ; Double Precision Add
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xor idx,idx ; No signs get switched
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lab DOADD
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MOV ibx,offset ADDJMPTAB
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lab INITIL
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MOV AL,Tag[idi] ; Get tags to determine special cases.
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SHL AL,1
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SHL AL,1
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OR AL,Tag[isi]
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CBI
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ifdef i386
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SHL iax,2
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else
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SHL iax,1
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endif
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ADD ibx,iax ; BX now points to address of proper routine.
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XOR DH,Flag[idi] ; Sign A
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XOR DL,Flag[isi] ; Sign B
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MOV CX,Expon[idi] ; Exponent of operand A
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MOV AX,Expon[isi] ; Exponent of operand B
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JMP cs:[ibx] ; Go to appropriate routine.
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page
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;-----------------------------------------------------------;
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; ;
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; Special Case Routines for Arithmetic Functions ;
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; ;
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;-----------------------------------------------------------;
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lab DDD
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mov isi,idi ;return DI with sign from Add/Subtract
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mov dl,dh
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lab SSS ;Return SI with sign from Add/Subtract
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call MOVresult
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MOV Flag[idi],dl ;Overstore correct Sign from Add/Subtract
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ret
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lab D0SSINV ;Return SI, set both Invalid and Zerodivide
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OR [CURerr],ZeroDivide
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JMP short SSINV
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lab DDINV ;Return DI and set Invalid exception
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MOV isi,idi
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lab SSINV ;Return SI and set INVALID exception
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OR [CURerr],Invalid
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jmp short MOVresult
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lab ZEROS ;Return 0 with xor of signs
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MOV isi,offset IEEEzero
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lab XORSIGN
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XOR DH,DL
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AND DH,80h ; Mask to just the sign.
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CALL csMOVresult
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OR Flag[idi],DH
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RET
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lab DIV0 ;Set exception, Return Infinity signed
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OR [CURerr],ZeroDivide
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lab INFS ;Return signed infinity
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MOV isi,offset IEEEinfinity
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JMP XORSIGN
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lab D0INDINV ;Set div 0 exception, Return Indefinate and Invalid
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OR [CURerr],ZeroDivide
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lab INDINV
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MOV isi,offset IEEEindefinite
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OR [CURerr],Invalid
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lab csMOVresult
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mov idi,[RESULT]
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lab csMOVRQQ ; as above for constants in CS
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ifdef i386
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MOVS dword ptr es:[idi],dword ptr cs:[isi]
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MOVS dword ptr es:[idi],dword ptr cs:[isi]
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MOVS dword ptr es:[idi],dword ptr cs:[isi]
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else
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MOVS word ptr es:[idi],word ptr cs:[isi]
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MOVS word ptr es:[idi],word ptr cs:[isi]
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MOVS word ptr es:[idi],word ptr cs:[isi]
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MOVS word ptr es:[idi],word ptr cs:[isi]
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MOVS word ptr es:[idi],word ptr cs:[isi]
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MOVS word ptr es:[idi],word ptr cs:[isi]
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endif
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SUB idi,Reg87Len
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SUB isi,Reg87Len
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RET
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lab MOVresult
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mov idi,[RESULT] ; move to result
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cmp isi,idi
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je short MOVret ; unless the same
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lab MOVRQQ
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ifdef i386
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MOVS dword ptr es:[idi],dword ptr ds:[isi]
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MOVS dword ptr es:[idi],dword ptr ds:[isi]
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MOVS dword ptr es:[idi],dword ptr ds:[isi]
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else
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MOVS word ptr es:[idi],word ptr ds:[isi]
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MOVS word ptr es:[idi],word ptr ds:[isi]
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MOVS word ptr es:[idi],word ptr ds:[isi]
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MOVS word ptr es:[idi],word ptr ds:[isi]
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MOVS word ptr es:[idi],word ptr ds:[isi]
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MOVS word ptr es:[idi],word ptr ds:[isi]
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endif
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SUB idi,Reg87Len
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SUB isi,Reg87Len
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lab MOVret
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RET
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lab INFINF ; Addition of two infinities was attempted
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TEST [CWcntl],InfinityControl ; Invalid if projective closure
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JSZ INDINV
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XOR DL,DH ; Invalid if signs are different
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JSS INDINV
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JMP DDD ; Otherwise Inf is the answer, already at DI
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lab BIGNAN ; Return the NAN with the Bigger mantissa
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mov iax, isi
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mov ibx, idi
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add isi, MantissaByteCnt-2 ; UNDONE387: Convert SNAN to QNAN
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add idi, MantissaByteCnt-2
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mov icx, MantissaByteCnt/2
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std
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repe cmps word ptr ds:[isi], word ptr es:[idi]
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cld
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JSB DDNAN
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mov isi, iax ; Greater NAN was in si
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jmp SSINV
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lab DDNAN
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mov isi, ibx ; Greater NAN was in di
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jmp SSINV
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page
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if fastSP
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ifdef i386
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BUG ; fastsp and i386 do not work together
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endif
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;Assumes DL = Flag[SI], DH = Flag[DI]. Will convert the mantissa on
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;stack to double if necessary by appending zeros.
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;Must not change AX, DX, SI, DI.
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lab CoerceToDouble
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MOV BX,DX ; get to work reg
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AND BX,Single + 256*Single ; mask to single flags only
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JSNZ CheckDI
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lab CoerceToDoubleReturn
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RET
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lab CheckDI
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XOR BX,BX ; Prepare to zero out mantissa
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XCHG AX,BX
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TEST DH,Single
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JSZ CheckSI
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STOSW ; Zero out lower five bytes
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STOSW
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STOSB
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SUB DI,5 ; Reset DI
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lab CheckSI
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TEST DL,Single
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JZ short ExitCoerceToDouble
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XCHG DI,SI
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STOSW ; Zero out lower five bytes
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STOSW
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STOSB
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SUB DI,5 ; Reset DI
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XCHG DI,SI
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lab ExitCoerceToDouble
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XCHG AX,BX ; Reset AX
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XOR BX,BX ; Set zero flag to indicate results now double
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RET
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endif ;fastSP
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ProfEnd ARITH
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