How to read and write x86 flags registers directly?

Question

From what I\'ve read, seems like there are 9 different flags. Is it possible to read/change them directly? I know I can know for example if the zero flag is set after doing

Answer 1

• LAHF: loads status flags into AH
• Copies the low byte of the EFLAGS register including Sign, Zero, and Carry flags.

• Save a copy of the flags in a variable for safekeeping

  .data
   saveflags BYTE ? 
  .code 
   lahf ; load flags into AH 
   mov saveflags,ah ; save them into a variable 
  

• SAHF: stores AH into status flags

• Copies AH into the low byte of the EFLAGS register

• Retrieve the value of flags stored earlier

  .code
   mov ah, saveflags ; load save flags into AH 
   sahf ; copy into flags register