Encoding:

P32A

001000

rt

x

ac

00

000

001

111

111

6

5

5

2

2

3

3

3

3

Format: 

MFHI rs, ac

DSP

Move from HI register

Purpose:

Move from HI register

To copy the special purpose HI register to a GPR.

Description: 

rs = HI[ac]

The HI part of accumulator ac is copied to the general-purpose register rs. The HI part of the accumulator is defined to be bits 32 through 63 of the DSP Module accumulator register.

The value of ac can range from 0 to 3. When ac=0, this refers to the original HI/LO register pair of the MIPS32 architecture.

In Release 6 of the MIPS Architecture, accumulators are eliminated from MIPS32.

Restrictions:

No data-dependent exceptions are possible.

The operands must be values in the specified format. If they are not, the results are UNPREDICTABLE and the values of the operand vectors become UNPREDICTABLE.

Operation: 

if (( ac != 0 ) or (ConfigAR >= )) then 
   ValidateAccessToDSPResources()
endif
GPR[rs]31..0 = HI[ac]31..0

Exceptions:

Reserved Instruction, DSP Disabled