R01UH0822EJ0100 Rev.1.00
Page 53 of 1041
Jul 31, 2019
RX13T Group
2. CPU
2.2.3
Register Associated with DSP Instructions
2.2.3.1
Accumulator (ACC)
The accumulator (ACC) is a 64-bit register used for DSP instructions. The accumulator is also used for the multiply and
multiply-and-accumulate instructions; EMUL, EMULU, FMUL, MUL, and RMPA, in which case the prior value in the
accumulator is modified by execution of the instruction.
Use the MVTACHI and MVTACLO instructions for writing to the accumulator. The MVTACHI and MVTACLO
instructions write data to the higher-order 32 bits (bits 63 to 32) and the lower-order 32 bits (bits 31 to 0), respectively.
Use the MVFACHI and MVFACMI instructions for reading data from the accumulator. The MVFACHI and MVFACMI
instructions read data from the higher-order 32 bits (bits 63 to 32) and the middle 32 bits (bits 47 to 16), respectively.
Range for reading by MVFACMI
b63
b48 b47
b32
b31
b16 b15
b0
Range for reading and writing by
MVTACHI and MVFACHI
Range for writing by MVTACLO
Value after reset:
Undefined