Samsung S3C8275X User Manual
Page 174
INSTRUCTION SET
S3C8275X/F8275X/C8278X/F8278X/C8274X/F8274X
6-40
EI
—
Enable Interrupts
EI
Operation: SYM
(0)
← 1
An EI instruction sets bit zero of the system mode register, SYM.0 to "1". This allows interrupts to
be serviced as they occur (assuming they have 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 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.)