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Intel Pentium Instruction Set Reference

SAHF - Store AH into Flags

Code Mnemonic Description
9E SAHF Loads SF, ZF, AF, PF, and CF from AH into EFLAGS register

Description

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.

Operands Bytes Clocks
1 2 NP

Flags

ID unaffected DF unaffected
VIP unaffected IF unaffected
VIF unaffected TF unaffected
AC unaffected SF loaded with values from the AH register
VM unaffected ZF loaded with values from the AH register
RF unaffected AF loaded with values from the AH register
NT unaffected PF loaded with values from the AH register
IOPL unaffected CF loaded with values from the AH register
OF unaffected