x86 Instruction Set Reference
STD
Set Direction Flag
| Opcode | Mnemonic | Description |
|---|---|---|
FD |
STD |
Set DF flag. |
| Description |
|---|
|
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). |
| Operation |
|---|
DF = 1; |
| Flags affected |
|---|
|
The DF flag is set. The CF, OF, ZF, SF, AF, and PF flags are unaffected. |