x86 Instruction Set Reference
SAHF
Store AH into Flags
Opcode | Mnemonic | Description |
---|---|---|
9E |
SAHF |
Load SF, ZF, AF, PF, and CF from AH into EFLAGS register. |
Description |
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Loads the SF, ZF, AF, PF, and CF flags of the EFLAGS register with values from the corresponding bits in the AH register (bits 7, 6, 4, 2, and 0, respectively). Bits 1, 3, and 5 of register AH are ignored; the corresponding reserved bits (1, 3, and 5) in the EFLAGS register remain as shown in the "Operation" section below. |
Operation |
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EFLAGS(SF:ZF:0:AF:0:PF:1:CF) = AH; |
Flags affected |
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The SF, ZF, AF, PF, and CF flags are loaded with values from the AH register. Bits 1, 3, and 5 of the EFLAGS register are unaffected, with the values remaining 1, 0, and 0, respectively. |
Instruction | Latency | Throughput | Execution Unit |
---|---|---|---|
CPUID | 0F3n/0F2n | 0F3n/0F2n | 0F2n |
SAHF | 1/0.5 | 0.5/0.5 | ALU |