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ei
Function
Enable interrupts
Standard)
Extension 1) Unusable
Extension 2) Unusable
15 14 13 12 11 10
Code
0
0
0
|
|
IL
IE
C
Flag
|
|
–
1
–
Mode
–
CLK
One cycle
Description
(1) Standard
Sets the IE bit in the PSR to enable external maskable interrupts.
(2) Delayed slot instruction
This instruction may be executed as a delayed slot instruction by writing it directly after a
branch instruction with the "d" bit.
Example
ei
Caution
Maskable interrupts are enabled from the third cycle after the ei instruction has been executed.
ei
Instruction 1
Instruction 2
Instruction 3
Example: Interrupt disabled periods using the di and ei instructions
ld %r2,%r3
di
ld.a %r0,%r1
ld.b %r2,%r3
ld %r4,%r5
ei
add %r4,%r5
sub %r6,%r7
cmp %r0,%r1
S1C17 CORE MANUAL
(Rev. 1.2)
psr(IE) ← 1
9
8
7
6
|
0
0
0
0
0
0
0
|
|
|
|
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V
Z
N
|
|
|
–
–
–
; Enables external maskable interrupts.
← 1-cycle instruction
← 1-cycle instruction
← Interrupts are enabld from this instruction.
← Interrupt enabled
← Interrupt enabled
← Interrupt enabled
← Interrupt enabled
← Interrupt disabled
← Interrupt disabled
← Interrupt disabled
← Interrupt disabled
← Interrupt enabled
Seiko Epson Corporation
5
4
3
2
1
0
1
0
0
0
0
0
|
|
|
|
|
|
7 DETAILS OF INSTRUCTIONS
7-33
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