Chapter 16AppendixXVI - 72 Extension Instruction Specification2) Precautions for describing word/halfword data multiply and accumulate instruction and multiply and accu-mulate instructionWhen a word/halfword data multiply and accumulate instruction and multiply and accumulate instructionare executed continuously with the former instruction preceding the latter, the result of the word/halfworddata multiply and accumulate instruction is used to execute the sequential multiply and accumulateinstruction. For this reason, the next multiply and accumulate instruction must be activated after theresult of the word/halfword data multiply and accumulate instruction, that is required for the multiply andaccumulate instruction, has been output. Therefore, it is necessary to provide 2 cycles between thepreceding word/halfword data multiply and accumulate instruction and the succeeding multiply andaccumulate instruction.Figure:16.4.4 Drawing of Pipelining for Precaution (2)This precaution is applicable to the following instructions:MAC, MACI, MACH, MACIH, MACU, MACIU, MACHU and MACIHU instructionsMAC, MACI, MACH, MACIH, MACU, MACIU, MACHU, MACIHU, MACB, MACIB,MACBU and MACIBU instructionsDECWord/halfword datamultiply and accumulateinstruction (1)Insert 2 cycles Result availablefor referenceMultiply and accumulateinstruction (2)Instructiondecoding InstructiondecodingOperation OperationMultiply and accumulateinstruction (1) outputsthe result required formultiply and accumulateinstruction (2)EXMEMWB
