Volume 3: General-Purpose and System Instructions - Stanford ...

Volume 3: General-Purpose and System Instructions - Stanford ... Volume 3: General-Purpose and System Instructions - Stanford ...

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AMD64 Technology 24594 Rev. 3.10 February 2005CBWCWDECDQEConvert to Sign-extendedCopies the sign bit in the AL or eAX register to the upper bits of the rAX register. Theeffect of this instruction is to convert a signed byte, word, or doubleword in the AL oreAX register into a signed word, doubleword, or double quadword in the rAX register.This action helps avoid overflow problems in signed number arithmetic.The CDQE mnemonic is meaningful only in 64-bit mode.Mnemonic Opcode DescriptionCBW 98 Sign-extend AL into AX.CWDE 98 Sign-extend AX into EAX.CDQE 98 Sign-extend EAX into RAX.Related InstructionsCWD, CDQ, CQOrFLAGS AffectedNoneExceptionsNone96 CBW, CWDE, CDQE

24594 Rev. 3.10 February 2005 AMD64 TechnologyCWDCDQCQOConvert to Sign-extendedCopies the sign bit in the rAX register to all bits of the rDX register. The effect of thisinstruction is to convert a signed word, doubleword, or quadword in the rAX registerinto a signed doubleword, quadword, or double-quadword in the rDX:rAX registers.This action helps avoid overflow problems in signed number arithmetic.The CQO mnemonic is meaningful only in 64-bit mode.Mnemonic Opcode DescriptionCWD 99 Sign-extend AX into DX:AX.CDQ 99 Sign-extend EAX into EDX:EAX.CQO 99 Sign-extend RAX into RDX:RAX.Related InstructionsCBW, CWDE, CDQErFLAGS AffectedNoneExceptionsNoneCWD, CDQ, CQO 97

24594 Rev. 3.10 February 2005 AMD64 TechnologyCWDCDQCQOConvert to Sign-extendedCopies the sign bit in the rAX register to all bits of the rDX register. The effect of thisinstruction is to convert a signed word, doubleword, or quadword in the rAX registerinto a signed doubleword, quadword, or double-quadword in the rDX:rAX registers.This action helps avoid overflow problems in signed number arithmetic.The CQO mnemonic is meaningful only in 64-bit mode.Mnemonic Opcode DescriptionCWD 99 Sign-extend AX into DX:AX.CDQ 99 Sign-extend EAX into EDX:EAX.CQO 99 Sign-extend RAX into RDX:RAX.Related <strong>Instructions</strong>CBW, CWDE, CDQErFLAGS AffectedNoneExceptionsNoneCWD, CDQ, CQO 97

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