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Extension Instruction Specifications
3-32
(a) Note on the description of word/half-word data multiply-and-accumulate instructions and multiply-and-
accumulate instructions
When executing a word/half-word data multiply-and-accumulate instruction followed by a multiply-and-accumulate
instruction, the result produced by the word/half-word data multiply-and-accumulate instruction is used in the
execution of the subsequent multiply-and-accumulate instruction. Therefore, it is essential to not initiate the
subsequent multiply-and-accumulate instruction until after the result that is required from the word/half-word data
multiply-and-accumulate instruction has been output. As a result, one cycle must be inserted between the word/
half-word data multiply-and-accumulate instruction and the subsequent multiply-and-accumulate instruction.
This note applies to the following instructions:
<Word/half-word data multiply-and-accumulate instructions>
MAC instruction, MACH instruction, MACU instruction, MACHU instruction
<Multiply-and-accumulate instructions>
MAC instruction, MACH instruction, MACU instruction, MACHU instruction, MACB instruction,
MACBU instruction
Instruction
decoding
DEC
EX
MEM
WB
Instruction decoding
Operation
Word/half-word data
Multiply-and-
accumulate instruction (2)
Insert one cycle
Multiply-and-ac
c
umulate
instruction (1) has output the
result that is required by
multiply-and-accumulate
instruction (2)
Result can be
referenced
Multiply-and-accumulate instruction (1)
Operation