Assembly: 

EI rt

nanoMIPS. Requires CP0 privilege.

Enable Interrupts

Purpose:

Enable Interrupts.

Enable interrupts by setting Status.IE to 1, and return the previous

value of Status register in register $rt.

Availability:

nanoMIPS. Requires CP0 privilege.

Format:

001000

rt

x

01

01011

101

111

111

6

5

5

2

5

3

3

3

Operation: 

if not IsCoprocessor0Enabled():
    raise coprocessor_exception(0)
GPR[rt] = C0.Status
C0.Status.IE = 1

Exceptions:

Coprocessor Unusable.