Lds/les instruction execution-microprocessor, Assembly Language

LDS/LES Instruction execution :

 LAHF: Load AH from Lower Byte of Flag: - This instruction loads the AH register with the lower byte of the flag register. This instruction can be utilized to observe the status of all the condition code flags (except over flow) at a time.

SAHF: Store AH to Lower Byte of Flag Register. This instruction resets or sets the condition code flags (except overflow) in the lower byte of the flag register depending on the equivalent bit positions in AH. If a bit in AH is value1, the flag equivalent to the bit position is set, else it is reset.

PUSHF: Push Flags to Stack: - The push flag instruction pushes the flag register on the stack; first the upper byte and then the lower byte will be pushed on the stack. The SP is decremented by value 2, for each push operation. The basic operation of this instruction is same to the PUSH operation.

POPF: Pop Flags from Stack:-The pop flags instruction loads the flag register totally (both bytes) from the word contents of the memory location currently addressed by SS and SP. The SP is incremented by the value 2 for each pop operation.

Posted Date: 10/12/2012 12:57:52 AM | Location : United States







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