Panasonic MN103S User Manual page 526

Chapter 16
Appendix
4) Precautions for describing byte data multiply and accumulate instruction and multiply and accumulate
instruction
When a byte data multiply and accumulate instruction and multiply and accumulate instruction are
executed continuously, the result of the byte data multiply and accumulate instruction is used to execute
the multiply and accumulate instruction. For this reason, the next multiply and accumulate instruction
must be activated after the result of the byte data multiply and accumulate instruction, that is required for
the multiply and accumulate instruction, has been output. Therefore, it is necessary to provide 1 cycle
between the preceding byte data multiply and accumulate instruction and the succeeding multiply and
accumulate instruction.
This precaution is applicable to the following instructions:
<Byte data multiply and accumulate instructions>
MACB, MACIB, MACBU and MACIBU instructions
<Multiply and accumulate instructions>
MAC, MACI, MACH, MACIH, MACU, MACIU, MACHU, MACIHU, MACB, MACIB,
MACBU and MACIBU instructions
XVI - 74 Extension Instruction Specification
Insert 1 cycle
Byte data multiply and
accumulate instruction (1)
DEC
Instruction
decoding
EX
MEM
WB
Figure:16.4.6 Drawing of Pipelining for Precaution (4)
Result available
for reference
Multiply and accumulate
instruction (2)
Instruction
decoding
Operation
Operation
Multiply and accumulate
instruction (1) outputs
the result required for
multiply and accumulate
instruction (2)