\subsection{\index{neg}neg}

\index{negation}
NEGation


\begin{tabular}{l}
  {\bf neg r2, r1} \\
  {\bf sneg r2, r1} \\
\end{tabular}

~~~~~~
Computes r1 = not(r2) + 1

~~~~~~
This instruction negates the source operand in a special unit that
is designed for low latency when large data are processed.

~~~~~~
This instruction is designed to work in the 2s-complement numbering sytem
(signed integer numbers) and is not subject to saturation/overflow problems.
Notice though that negating -128'' (if bytes are treated) will nicely
fail to give you +128, without trapping. You've been warned.

\begin{center}

\begin{tabular}{|l|l|l|l|l|l|}
 \hline
\multicolumn{1}{|r| }{size :
} & \multicolumn{1}{c| }{8
} & \multicolumn{1}{c| }{6
} & \multicolumn{1}{c| }{6
} & \multicolumn{1}{c| }{6
} & \multicolumn{1}{c| }{6
 } \\
 \hline
\multicolumn{1}{|r| }{bits :
} & {31 ~ ~ ~ ~ ~ ~ ~ ~ 24
} & {23 ~ ~ ~ ~ ~ ~ 18
} & {17 ~ ~ ~ ~ ~ ~ 12
} & {11 ~ ~ ~ ~ ~ ~ 6
} & {5 ~ ~ ~ ~ ~ ~ 0
 } \\
 \hline
\multicolumn{1}{|r| }{function :
} & \multicolumn{1}{c| }{OP\_NEG
} & \multicolumn{1}{c| }{Flags
} & \multicolumn{1}{c| }{0
} & \multicolumn{1}{c| }{Reg 2
} & \multicolumn{1}{c| }{Reg 1
}
\\ \hline

\end{tabular}



\begin{tabular}{|l|l|l|l|}
 \hline
\multicolumn{1}{|c| }{~ ~ Flags ~ ~
} & \multicolumn{1}{c| }{Syntax
} & {Values
} & {Function
 } \\
 \hline
\multicolumn{1}{|c| }{23-22
} & {.q, .d or .b postfix
} & {*
} & {Defines the size parameter
 } \\
 \hline
\multicolumn{1}{|c| }{21
} & {s- prefix
} & {1 if set
} & {Defines if the operation is SIMD
 } \\
 \hline
\multicolumn{1}{|c| }{20-18
} & {(none yet)
} & {0
} & {Reserved
}
\\ \hline

\end{tabular}


~

{\bf Example : }
\end{center}


R1 contains 0xFF05891213450100 (in a 64-bit system)

{\tt
{\bf sneg.b r1,r2 }: r2 = 0x01FB77EEEDBBFF00 \\
}

\begin{center}
{\bf Performance (FC0 only) :}
\end{center}


{\em Execution Unit :} Increment Unit\\
{\em Latency :} 1 cycle\\
{\em Throughput :} 1 per cycle per IU.\\

~

\pagebreak

