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Minor tweaks and added a note or two.

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Garritt McCune
2024-07-19 16:26:21 -05:00
parent 8003d389e9
commit b1e3e585f4
1 changed files with 6 additions and 5 deletions
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chapter 2.tex
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@@ -20,14 +20,15 @@
\usetikzlibrary{decorations.pathreplacing}
\section{Encoding Scheme}
There are two basic encoding schemes that the object code will take. The most basic layout is shown in Figure \ref{fig:OpShortEncodingFigure} that is used by instructions that take one or zero arguments, where the 16 most significant bits are used to encode the instruction itself. Followed by the 16 least significant bits being used to encode a numeric constant that may be interpreted as a relative address. For instructions that require two arguments the encoding scheme shown in Figure \ref{fig:OpArgEncodingFigure} is used.
%Placement info here: https://en.wikibooks.org/wiki/LaTeX/Floats,_Figures_and_Captions#Figures
All instructions are a fixed width of 32-bits. There are two basic encoding schemes that the object code will take. The most basic layout is shown in Figure \ref{fig:OpShortEncodingFigure} that is used by instructions that take one or zero arguments, where the 16 most significant bits are used to encode the instruction itself. Followed by the 16 least significant bits being used to encode a numeric constant that may be interpreted as a relative address. For instructions that require two arguments the encoding scheme shown in Figure \ref{fig:OpArgEncodingFigure} is used.
% Placement info here: https://en.wikibooks.org/wiki/LaTeX/Floats,_Figures_and_Captions#Figures
% Paths: https://tikz.dev/tikz-paths
\begin{figure}[h]
\begin{tikzpicture}
\draw (\minX, 0) -- (\maxX, 0);
\draw (\minX, \minY / 2) -- (\minX, \maxY / 2); %{$y$}; Note the $'s, those make something math stylized.
\draw (\maxX, \minY / 2) -- (\maxX, \maxY / 2);
\draw (0, \minY / 2) -- (0, \maxY / 2); % Halfway mark
\draw (\maxX, \minY / 2) -- (\maxX, \maxY / 2);
\draw (\minX, -\maxY) node[below=1em] {31} [decorate, decoration={brace, amplitude=1em, mirror}] -- (0, -\maxY) node[below=1em] {16} node[midway, below=1em] {Op Code (16-bits)};
\draw (0, \maxY) node[above=1em] {15} [decorate, decoration={brace, amplitude=1em}] -- (\maxX, \maxY) node[above=1em] {0} node[midway, above=1em] {Near Address (16-bits)};
\end{tikzpicture}
@@ -38,9 +39,9 @@ There are two basic encoding schemes that the object code will take. The most ba
\begin{tikzpicture}
\draw (\minX, 0) -- (\maxX, 0);
\draw (\minX, \minY / 2) -- (\minX, \maxY / 2); %{$y$}; Note the $'s, those make something math stylized.
\draw (\maxX, \minY / 2) -- (\maxX, \maxY / 2);
\draw (0, \minY / 2) -- (0, \maxY / 2); % Halfway mark
\draw [dotted] (\maxX / 2, \minY / 2) -- (\maxX / 2, \maxY / 2); % Halfway mark for the lower 16 bits
\draw (\maxX, \minY / 2) -- (\maxX, \maxY / 2);
\draw (\maxX / 2, \minY / 2) -- (\maxX / 2, \maxY / 2); % Halfway mark for the lower 16 bits
\draw (\minX, -\maxY) node[below=1em] {31} [decorate, decoration={brace, amplitude=1em, mirror}] -- (0, -\maxY) node[below=1em] {16} node[midway, below=1em] {Op Code (16-bits)};
\draw (0, \maxY) node[above=1em] {15} [decorate, decoration={brace, amplitude=1em}] -- (\maxX / 2, \maxY) node[above=1em] {8} node[midway, above=1em] {Destination};
\draw (\maxX / 2, -\maxY) node[below=1em] {7} [decorate, decoration={brace, amplitude=1em, mirror}] -- (\maxX, -\maxY) node[below=1em] {0} node[midway, below=1em] {Source};