Samsung S3F84B8 - EI - Enable Interrupts

S3F84B8_UM_REV 1.00 6 INSTRUCTION SET
6-39
6.3.27 EI — ENABLE INTERRUPTS
EI
Opera
tion: SYM (0)  1
An EI instruction sets the bit zero of system mode register, SYM.0, to “1”. This allows the
interrupts to be serviced as they occur (assuming they have the highest priority). If an interrupt’s
pending bit was set while interrupt processing was disabled (by executing a DI instruction), it will
be serviced when you execute the EI instruction.
Flags: No flags are affected.
Format:
Bytes Cycles Opcode
(Hex)
opc 1 4 9F
Example: Given SYM = 00H:
EI
If the SYM register contains the value 00H, that is, if the interrupts are currently disabled, the
statement “EI” sets the SYM register to 01H, enabling all interrupts. (SYM.0 is the enable bit for
global interrupt processing.)