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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
<title>Apoo assembly language</title>
</head>
<body>
<h1><tt>Apoo</tt> assembly language</h1>
<tt>Apoo</tt> has a set of general purpose
registers (32 by default), a data memory area, a program memory
area, a system stack and a program counter register.
<p>All memory cells and registers have 32 bits.</p>
<p>Registers are named R0,R1,R2,R3,R4,R5,R6,R7,...</p>
<h2>Memory Data</h2>
Memory cells are created as needed. We can reserve memory cells
in two ways, using the following pseudo-instructions:
<h2>Pseudo-instructions</h2>
<p>
<table border="1" cellpadding="3">
<tbody>
<tr>
<td align="left"> </td>
<td align="left"> </td>
<td width="170"> </td>
<th width="170"><span class="textbf">Meaning</span></th>
</tr>
<tr>
<td align="left"><tt><Label:></tt></td>
<td align="left"><tt>mem</tt></td>
<td width="170"><tt>n</tt></td>
<td width="170">reserves n memory addresses</td>
</tr>
<tr>
<td align="left"><tt>Label:</tt></td>
<td align="left"><tt>const</tt></td>
<td width="170"><tt>n1</tt></td>
<td width="170">contents of memory address</td>
</tr>
<tr>
<td align="left"> </td>
<td align="left"><tt>const</tt></td>
<td width="170"><tt>n2</tt></td>
<td width="170"><tt>Label</tt> is <tt>n1</tt>, of Label+1 is <tt>n2</tt></td>
</tr>
<tr>
<td align="left"> </td>
<td align="left"> </td>
<td width="170">....</td>
<td width="170"><tt>ni</tt> can be a character <tt>'c'</tt>.</td>
</tr>
<tr>
<td align="left"><tt><Label:></tt></td>
<td align="left"><tt>equ</tt></td>
<td width="170"><tt>n</tt></td>
<td width="170">Allows a symbolic
name for a number</td>
</tr>
<tr>
<td align="left"><tt><Label:></tt></td>
<td align="left"><tt>string</tt></td>
<td width="170"><tt>"seqNWSCharacteres"</tt></td>
<td width="170">Allocates memory
addresses and set them to the correspondent characters ASCII
codes. The characters cannot be whitespaces: use <code>\s</code> for
<tt>space</tt>, <code>\t</code> for <tt>tab</tt> and <code>\n</code> for <tt>newline</tt>.</td>
</tr>
</tbody>
</table>
</p>
<p><tt>Label</tt> is any string beginning with a letter and containing only letters
and digits with the exception of legal register names. If exists, must
begin in the first column of a line</p>
<p><span class="textbf">NOTE:</span> Every memory address refered, must have been reserved by
one of the previous pseudo-instructions.</p>
<p>E.g. the instruction <tt>load 3 R2</tt>, will cause an <tt>Out of
Memory</tt> error, if at least <tt>mem 3</tt> or three <tt>const</tt>
pseudo-instructions were not given...
If a <tt>equ</tt> value is used as a memory address, that address must
be already reserved or be a known memory-mapped instruction. The
<tt>string</tt> argument must be quoted and is converted to a sequence of ascii
codes ending with <tt>0</tt>.</p>
<h2>System Stack</h2>
<p>A special memory area used to implement subroutines. We can only push
a value to the Stack and pop a value from it (the one in the
top of the Stack).
It is used by the instructions jsr and rtn.
It can be manipulated by means of the <tt>push</tt> and <tt>pop</tt> instructions.</p>
<h2>Instruction Form</h2>
<pre><Label:> Operation <Operand1> <Operand2><br></pre>
<p><tt>Label</tt> is any string of letters or digits; if exists, must begin in the
first column of a line</p>
<h2>Comments</h2>
<p>A line beginning with # will be ignored by the parser; so it can be
used to write comments of the program</p>
<h2>Instruction Set</h2>
<p>
<table border="1" cellpadding="3">
<tbody>
<tr>
<td style="font-weight: bold;" align="left">Operation</td>
<td style="font-weight: bold;" align="left">Operand1</td>
<td style="font-weight: bold;" align="left">Operand2</td>
<td style="font-weight: bold;" width="227">Meanning</td>
</tr>
<tr>
<td align="left">load</td>
<td align="left">Mem</td>
<td align="left">Ri</td>
<td width="227">loads contents of memory
address Mem into register Ri;
Mem can be a label</td>
</tr>
<tr>
<td align="left">loadn</td>
<td align="left">Num</td>
<td align="left">Ri</td>
<td width="227">loads number Num into register
Ri; Num can be a label</td>
</tr>
<tr>
<td align="left">loadi</td>
<td align="left">Ri</td>
<td align="left">Rj</td>
<td width="227">loads contents of memory
which address is the contents
of Ri into Rj (indirect load)</td>
</tr>
<tr>
<td align="left">store</td>
<td align="left">Ri</td>
<td align="left">Mem</td>
<td width="227">stores contents of Ri at memory
address Mem; Mem can be a label</td>
</tr>
<tr>
<td align="left">storer</td>
<td align="left">Ri</td>
<td align="left">Rj</td>
<td width="227">stores contents of Ri into Rj</td>
</tr>
<tr>
<td align="left">storei</td>
<td align="left">Ri</td>
<td align="left">Rj</td>
<td width="227">stores contents of Ri
into at memory address, which is the
contents of Rj</td>
</tr>
<tr>
<td align="left">add</td>
<td align="left">Ri</td>
<td align="left">Rj</td>
<td width="227">add contents of register Ri to
contents of register Rj, and
stores into Rj (Rj=Ri+Rj)</td>
</tr>
<tr>
<td align="left">sub</td>
<td align="left">Ri</td>
<td align="left">Rj</td>
<td width="227">subtracts contents of register
Rj from contents of register Rj
and stores into Rj (Rj=Ri-Rj)</td>
</tr>
<tr>
<td align="left">mul</td>
<td align="left">Ri</td>
<td align="left">Rj</td>
<td width="227">multiplies contents of register
Ri and contents of register
Rj, and stores into Rj (Rj=Ri*Rj)</td>
</tr>
<tr>
<td align="left">div</td>
<td align="left">Ri</td>
<td align="left">Rj</td>
<td width="227">stores into Rj the quotient of integer
division of contents register
Ri by the contents of register
Rj, and stores into Rj (Rj=Ri/Rj)</td>
</tr>
<tr>
<td align="left">mod</td>
<td align="left">Ri</td>
<td align="left">Rj</td>
<td width="227">stores into Rj the rest of integer
division of contents of register
Ri by the contents of register
Rj, and stores into Rj (Rj=Ri%Rj)</td>
</tr>
<tr>
<td align="left">zero</td>
<td align="left">Ri</td>
<td align="left"> </td>
<td width="227">the contents of Ri becomes 0 (Ri=0)</td>
</tr>
<tr>
<td align="left">inc</td>
<td align="left">Ri</td>
<td align="left"> </td>
<td width="227">increments by 1 the contents of Ri</td>
</tr>
<tr>
<td align="left">dec</td>
<td align="left">Ri</td>
<td align="left"> </td>
<td width="227">decrements by 1 the contents of Ri</td>
</tr>
<tr>
<td align="left">jump</td>
<td align="left">Addr</td>
<td align="left"> </td>
<td width="227">jumps to instruction address Addr;
Addr can be a Label</td>
</tr>
<tr>
<td align="left">jzero</td>
<td align="left">Ri</td>
<td align="left">Addr</td>
<td width="227">jumps to instruction address Addr,
if contents of Ri is zero;
Addr can be a Label</td>
</tr>
<tr>
<td align="left">jnzero</td>
<td align="left">Ri</td>
<td align="left">Addr</td>
<td width="227"> jumps to instruction address Addr,
if contents of Ri is different
from zero;</td>
</tr>
<tr>
<td align="left">jpos</td>
<td align="left">Ri</td>
<td align="left">Addr</td>
<td width="227">jumps to instruction address Addr,
if contents of Ri is positiv;
Addr can be a Label</td>
</tr>
<tr>
<td align="left">jneg</td>
<td align="left">Ri</td>
<td align="left">Addr</td>
<td width="227">jumps to instruction address Addr,
if contents of Ri is
negativ</td>
</tr>
<tr>
<td align="left">jnzero</td>
<td align="left">Ri</td>
<td align="left">Addr</td>
<td width="227">jumps to instruction address Addr,
if contents of Ri is different
from zero;
Addr can be a Label</td>
</tr>
<tr>
<td align="left">jsr</td>
<td align="left">Addr</td>
<td align="left"> </td>
<td width="227">pushes the PC into the stack and
jumps to instruction address Addr</td>
</tr>
<tr>
<td align="left">rtn</td>
<td align="left"> </td>
<td align="left"> </td>
<td width="227">pops an address from the stack
into the PC</td>
</tr>
<tr>
<td align="left">push</td>
<td align="left">Ri</td>
<td align="left"> </td>
<td width="227">pushes the contents of Ri into the
system stack</td>
</tr>
<tr>
<td align="left">pop</td>
<td align="left">Ri</td>
<td align="left"> </td>
<td width="227">pops at element from the system stack
into Ri</td>
</tr>
<tr>
<td align="left">halt</td>
<td align="left"> </td>
<td align="left"> </td>
<td width="227">stops execution; Every program
must have this instruction in order
to end properly; otherwise an
'Out of Program' error will occur</td>
</tr>
</tbody>
</table>
</p>
<h2>Memory-Mapped Instructions</h2>
<p><tt>Apoo</tt> allows the configuration of a set of memory positions for
special purposes. The memory values and its functionality are given as
a parameter of the Apoo virtual machine.
The default values allow the simulation of input/output:</p>
<table style="text-align: left;" border="1" cellpadding="2" cellspacing="2">
<tbody>
<tr>
<td><span style="font-weight: bold;">Memory Position</span></td>
<td><span style="font-weight: bold;">Load</span></td>
<td width="227"><span style="font-weight: bold;">Store</span></td>
</tr>
<tr>
<td>50000</td>
<td><tt>load 50000 Ri<br>
<br>
</tt>loads 0 in <tt>Ri</tt></td>
<td width="227"><tt>store Ri 50000<br>
<br>
</tt>writes the character which ascii code is
<tt>Ri%256</tt> in the Output Window (in graphical interface) or in stdout,
in text mode.</td>
</tr>
<tr>
<td>50001</td>
<td><tt>load 50001 Ri<br>
<br>
</tt>reads an integer and stores it in Ri</td>
<td width="227"><tt>store Ri 50001<br>
<br>
</tt>writes the contents of Ri as an integer</td>
</tr>
<tr>
<td>50010</td>
<td><tt>load 50010 Ri<br>
<br>
</tt>loads 0 in <tt>Ri</tt></td>
<td width="227"><tt>store Ri 50010<br>
<br>
</tt>writes a CR in the Output Window (in graphical interface) or in stdout,
in text mode.</td>
</tr>
</tbody>
</table>
<p><br>
<br>
Here is an example:
</p>
<pre> loadn 97 R0<br> store R0 50000<br> store R0 50010<br> store R0 50001<br> store R0 50010<br> load 50001 R0<br> loadn 5 R1<br> add R0 R1<br> store R0 50001<br> store R0 50010<br> halt<br></pre>
<hr>
<p>© 1998-2006 Rogerio Reis, Nelma Moreira {rvr,nam}@ncc.up.pt</p>
</body>
</html>
|
