x86 Instruction Set Reference


Set Direction Flag

Opcode Mnemonic Description
FD STD Set DF flag.

Sets the DF flag in the EFLAGS register. When the DF flag is set to 1, string operations decrement the index registers (ESI and/or EDI).

DF = 1;
Flags affected

The DF flag is set. The CF, OF, ZF, SF, AF, and PF flags are unaffected.