Intel 253666-024US Manuel D’Utilisation

Vol. 2A 3-107

INSTRUCTION SET REFERENCE, A-M

CLD—Clear Direction Flag

CLD—Clear Direction Flag

Description

Clears the DF flag in the EFLAGS register. When the DF flag is set to 0, string opera-
tions increment the index registers (ESI and/or EDI). Operation is the same in all 
non-64-bit modes and 64-bit mode.

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.

Opcode

Instruction

64-Bit 

Mode

Compat/

Leg Mode

Description

FC

CLD

Valid

Valid

Clear DF flag.