cld

Clear Direction Flag

CLD

Sets DF to 0 (String operations increment).

Pseudocode Operation

DF ← 0

Encoding

Binary Layout

FC

+0

 

Format Legacy

Opcode FC

Extension Base

Operands

Related

More in Base

Reference

View in Intel® 64 and IA-32 Architectures SDM ↗ Intel® SDM

Instruction Forms

Opcode	Instruction	Op/En	64/32-bit Mode	CPUID	Description
FC	CLD	ZO	Valid Valid		Clear DF flag.

Description

Clears the DF flag in the EFLAGS register. When the DF flag is set to 0, string operations increment the index registers (ESI and/or EDI). Operation is the same in all modes.

Operation

DF := 0;

Flags Affected

The DF flag is set to 0. The CF, OF, ZF, SF, AF, and PF flags are unaffected. Exceptions (All Operating Modes) #UD If the LOCK prefix is used. CLD-Clear Direction Flag Vol. 2A 3-141