X86-assembly/Instructions/cdq

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X86-assembly

Instructions

cdq

Description

The CDQ (Convert Doubleword to Quadword) instruction extends the sign bit of EAX into the EDX register.

Syntax

cdq

Examples

mov   eax, 0x5   ; eax = 0x5, SF = 0
cdq              ; edx = 0x00000000

mov   eax, 0x5   ; eax = 0x5
neg   eax        ; eax = 0xFFFFFFFB, SF = 1
cdq              ; edx = 0xFFFFFFFF