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Diffstat (limited to 'src/m.tex')
| -rw-r--r-- | src/m.tex | 20 |
1 files changed, 20 insertions, 0 deletions
@@ -14,6 +14,7 @@ attached accelerators. \end{commentary} \section{Multiplication Operations} +\label{multiplication-operations} \vspace{-0.2in} \begin{center} @@ -166,3 +167,22 @@ unsigned divider implementations. Signed division is often implemented using an unsigned division circuit and specifying the same overflow result simplifies the hardware. \end{commentary} + +\section{Zmmul Extension, Version 0.1} + +The Zmmul extension implements the multiplication subset of the M extension. +It adds all of the instructions defined in Section~\ref{multiplication-operations}, +namely: MUL, MULH, MULHU, MULHSU, and (for RV64 only) MULW. +The encodings are identical to those of the corresponding M-extension instructions. + +\begin{commentary} +The Zmmul extension enables low-cost implementations that require +multiplication operations but not division. +For many microcontroller applications, division operations are too +infrequent to justify the cost of divider hardware. +By contrast, multiplication operations are more frequent, making the cost of +multiplier hardware more justifiable. +Simple FPGA soft cores particularly benefit from eliminating division but +retaining multiplication, since many FPGAs provide hardwired multipliers +but require dividers be implemented in soft logic. +\end{commentary} |