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Intel Pentium CPU Instruction Set Reference

CLD instruction - Clear Direction Flag

Code Mnemonic Description
FC CLD Clear DF flag


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).

Operands Bytes Clocks
  1 2 NP


ID unaffected DF cleared to 0
VIP unaffected IF unaffected
VIF unaffected TF unaffected
AC unaffected SF unaffected
VM unaffected ZF unaffected
RF unaffected AF unaffected
NT unaffected PF unaffected
IOPL unaffected CF unaffected
OF unaffected