30 lines
1.8 KiB
TeX
30 lines
1.8 KiB
TeX
\chapter{Overview}
|
|
This is an attempt to distill what I know about how computers work into some kind of emulator / simulator. I'm curious to see if what I know at the moment is enough to allow me to emulate a general purpose computer. A computer that will be big-endian, using 8-bit bytes for its char type. The memory is a 32 bit linear address space allowing for a maximum of 2\textsuperscript{32} bytes to be addressable.
|
|
\section{Registers}
|
|
Eight 32-bit general purpose registers are available for holding operands and memory addresses along with a Flags Register. The Flags Register is a 32-bit register allowing for 32 flags. Currently there are only arithmetic flags which are Overflow (OF), Underflow (UF), and a Zero Flag (ZF). The overflow flag is set if there is a carry. A base pointer register contains a 32 bit address that points to the start of the current stack frame, which is the first opcode of the stack frame. Therefore the first argument would be addressed as such:
|
|
\begin{verbatim}
|
|
mov r1, bp - sizeof(void *)
|
|
\end{verbatim}
|
|
Finally we have the Program Counter which contains a 32 bit address that points to the next instruction to execute.
|
|
\tikzstyle{blockRow} = [rectangle, minimum width=10cm, minimum height=0.5cm, text centered, draw=black]
|
|
|
|
%Note: tikzset might be better to use instead of tikzstyle.
|
|
\tikzset{
|
|
Rect/.style = {rectangle, fill=red!10!white}
|
|
}
|
|
\begin{figure}[!htb]
|
|
%\centering
|
|
\begin{tikzpicture}
|
|
\node at (1 ,0) {31};
|
|
%\node [Rect] at (0, 2) {test};
|
|
%\node at (0, )
|
|
\foreach \pos in {1,...,8} {
|
|
%\node at (0, \pos + 1) [blockRow] (\pos) {\pos};
|
|
\node at (0, \pos - 1) [blockRow] {r\pos};
|
|
;}
|
|
%\node [blockRow] (start) {r1};
|
|
%\node (r2) [blockRow] [below=of start] {r2};
|
|
\end{tikzpicture}
|
|
\caption{Register Bit Layout}
|
|
\end{figure}
|
|
\section{Memory Layout} |