src/cpc/raze/raze.html
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<h1 align="center">R. A. Z. E.</h1>
<p align="center">v1.06<br>
Copyright (c) 1999 <a href="#contact">Richard Mitton</a></p>
<hr color="#0000FF">
<h2>Introduction</h2>
<p>What is RAZE? It's a Zilog Z80 emulator for Intel x86 systems.<br>
If you use RAZE in a project, I'd love to hear about it.<br>
If RAZE doesn't work for you, I'd also like to hear about that.<br>
IF anyone needs any features adding, just ask. </p>
<p>Features include: </p>
<ul>
<li>Written in 100% 32-bit assembly language.</li>
<li>Standard C interface supplied.</li>
<li>Support for <strong>all</strong> opcodes, both documented and undocumented.</li>
<li>Calculates 99.9% of flags correctly, even undocumented ones.</li>
<li>Built-in support for bankswitching and mirrored memory.</li>
<li>Extensively tested against a real Z80.</li>
<li>Complete IRQ line support.</li>
<li>Correct R-register emulation.</li>
<li>Correct T-state cycle counting (probably).</li>
<li>Wait states.</li>
<li>Spectrum emulator example program. </li>
</ul>
<p>Lacking features:</p>
<ul>
<li>IM 0 can only be used with a RST opcode.</li>
<li>The 'patch' feature (it's not actually a proper Z80 opcode).</li>
<li>1 or 2 undocumented flags.</li>
<li>No M1 cycle emulation (i.e. no difference between opcodes/operands).</li>
<li>Could be faster (at the expense of features though). </li>
</ul>
<h2>Installation</h2>
<h3>DJGPP/GCC:</h3>
<p>Un-zip to a directory, and just run <kbd>MAKE</kbd>.</p>
<p><tt>NASM</tt> is required to assemble it. It currently uses <tt>NASM</tt>,
but you can edit the makefile if you need a different command. <i>Allegro</i>
is required if you want to run the example program. </p>
<h3>Other:</h3>
<p>Not tested, but you should be able to use it, as long as your compiler sticks
to the <em>GCC/MSVC</em> calling convention.</p>
<p>If the makefile doesn't work, then use <tt>NASM</tt> directly:</p>
<blockquote>
<p><kbd>nasm -e raze.asm -o raze2.asm<br>
</kbd><em>then<br>
</em><kbd>nasm -f coff raze2.asm -o raze.o -praze.reg</kbd></p>
</blockquote>
<p>Substitute <tt>COFF</tt> for whatever object format you need.<br>
You might need to use <tt>NASMW</tt> instead.<br>
If anyone can't get this working on non-DOS platforms, let me know! </p>
<p>Include "raze.h" in your program, and link with raze.o </p>
<hr>
<p align="center"><strong>For extra speed, you can edit RAZE.ASM and comment-out
some of the %define's.</strong></p>
<hr>
<h2><a name="#contact"></a>Contact information</h2>
<p>RAZE was written by <a
href="mailto:richard.mitton@bigfoot.com">Richard Mitton</a>.<br>
e-mail: <a href="mailto:richard.mitton@bigfoot.com">richard.mitton@bigfoot.com</a><br>
www: <a href="http://etc.home.dhs.org/">http://etc.home.dhs.org/ </a></p>
<h2>License & legal stuff</h2>
<p>You may use RAZE in any program you wish, however you are not allowed to sell
the programs without written permisson from Richard Mitton. </p>
<p>You may freely copy the source code to RAZE, as long as this archive stays
intact. </p>
<p>This program comes with absolutely <strong>NO WARRANTY</strong>. Richard Mitton
will not be held responsible for any problems due to RAZE. While all effort
has been made to ensure correct operation, use of RAZE is entirely at the user's
discretion. However, I will still try and help with problems whenever possible.</p>
<p><strong><u>Programs using RAZE must mention it in the documentation</u></strong>,
along with the text "RAZE Z80 core, by Richard Mitton (richard.mitton@bigfoot.com)".</p>
<h2>What's new</h2>
<table border="0" align="center">
<tr>
<td valign="top" width="8%"><u>v1.06:</u></td>
<td valign="top" width="82%">Um. This time I hope save states are <b>really</b>
fixed...</td>
</tr>
<tr>
<td valign="top" width="8%"><u>v1.05:</u></td>
<td valign="top" width="82%">Hopefully fixed a bug with save states...? (feedback
appreciated)</td>
</tr>
<tr>
<td valign="top" width="8%"><u>v1.04:</u></td>
<td valign="top" width="82%">Fixed MSVC support (thanks to <em>YANO Hirokuni</em>!),<br>
BIT instr now passes all ZEX tests,<br>
fixed support for Quazatron (thanks to <em>Charles Gallagher</em>!).</td>
</tr>
<tr>
<td valign="top" width="8%"><u>v1.03:</u></td>
<td valign="top" width="82%">Improved cycle timing slightly, added R-register
emulation,<br>
added an opcode-fetch callback option, added wait-states,<br>
also improved the example program a bit.</td>
</tr>
<tr>
<td valign="top" width="8%"><u>v1.02:</u></td>
<td valign="top" width="82%">Added post-EI interrupt behaviour</td>
</tr>
<tr>
<td valign="top" width="8%"><u>v1.01:</u></td>
<td valign="top" width="82%">Fixed to work with NASM v0.98,<br>
fixed reset code (thx to <em>Neil Bradley</em> ;)</td>
</tr>
<tr>
<td width="8%"><u>v1.00:</u></td>
<td valign="top" width="82%">First release.</td>
</tr>
</table>
<hr>
<h2>How to use it</h2>
<p>First, set up the memory-map, for example: </p>
<blockquote>
<p><code>z80_init_memmap();<br>
z80_map_fetch(0x0000, 0x7fff, &rom[0]);<br>
z80_map_fetch(0x8000, 0x9fff, &banked_rom[0]);<br>
z80_map_fetch(0xa000, 0xdfff, &ram[0]); </code></p>
<p><code>z80_add_read(0x0000, 0x7fff, Z80_MAP_DIRECT, &rom[0]);<br>
z80_map_read(0x8000, 0x9fff, &banked_rom[0]);<br>
z80_add_read(0xa000, 0xdfff, Z80_MAP_DIRECT, &ram[0]);<br>
z80_add_read(0xe000, 0xe001, Z80_MAP_HANDLED, &Read_SoundChip); </code></p>
<p><code>z80_add_write(0x0000, 0x7fff, Z80_MAP_DIRECT, &rom[0]);<br>
z80_map_write(0x8000, 0x9fff, &banked_rom[0]);<br>
z80_add_write(0xa000, 0xdfff, Z80_MAP_DIRECT, &ram[0]);<br>
z80_add_write(0xe000, 0xe001, Z80_MAP_HANDLED, &Write_SoundChip);<br>
z80_add_write(0xf000, 0xf001, Z80_MAP_HANDLED, &Write_Bankswitch);<br>
z80_end_memmap(); </code></p>
</blockquote>
<p>This defines the memory-map for a Z80. '<strong>fetch</strong>' is used for
instruction fetching, '<strong>read</strong>' is for reading memory, '<strong>write</strong>'
is for writing memory. </p>
<p>You can either specify an area as <var>Z80_MAP_DIRECT</var>, in which case
RAZE will directly read/write to it itself, or <var>Z80_MAP_HANDLED</var>, which
causes RAZE to call the given function instead. </p>
<ul>
<li>Note that <strong>NONE</strong> of the address should overlap at all.</li>
<li> Also note that for the <code>z80_map_?????</code> functions, the addresses
<strong>MUST</strong> be 256-byte aligned: e.g. it must start on <tt>0x8000</tt>,
and end on <tt>0x80ff</tt>. So the start address must be <tt>0xXX00</tt>,
end address must be <tt>0xYYff</tt>. </li>
</ul>
<table width="100%" align="center" bgcolor="#CCCCFF">
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<td>
<p>Once the memory-map has been defined, it can't be changed. So, in order
to accommodate bank-switching etc, you can use the 'map' functions: </p>
<blockquote>
<pre><code>void Write_Bankswitch(tUWORD addr, tUBYTE value)
{
/* map in a new bit of memory into the bank */
z80_map_fetch(0x8000, 0x9fff, &banked_rom[value * 0x2000]);
z80_map_read(0x8000, 0x9fff, &banked_rom[value * 0x2000]);
z80_map_write(0x8000, 0x9fff, &banked_rom[value * 0x2000]);
}</code></pre>
</blockquote>
<p>But! You can only map an area if it was set up using z80_map_????? to
start with! i.e. the ones set using z80_add_????? are fixed!</p>
</td>
</tr>
</table>
<p>If you haven't defined a bit of memory, the following will happen:<br>
<em>fetch</em>: it might crash, so don't do it.<br>
<em>read</em>: it will return 0xff as the value read.<br>
<em>write</em>: nothing. </p>
<p>This may all seem a bit complicated, but it is worth making use of it in order
to get the best performance. </p>
<hr>
<h2>I/O Ports & RetI</h2>
<p>If you want to use the I/O ports, do this:</p>
<blockquote>
<p><code>z80_set_in(&ReadInputPort);<br>
z80_set_out(&WriteOutputPort);</code></p>
</blockquote>
<p>RAZE will call the given function, for all ports.</p>
<ul>
<li>
<p><strong>NOTE:</strong> the port addresses are always 16-bit. If you need
8-bit ports, <u>you must AND the port address with 0xff first!</u> (just
like a real Z80 would, basically...)</p>
</li>
</ul>
<p>If you want to trap the RETI opcode, do this:</p>
<blockquote>
<p><code>z80_set_reti(&YourCustom_RETI_Handler); </code></p>
</blockquote>
<hr>
<h2>Main Loop & Interrupts</h2>
<p>Once that's all been done, you'll need to reset the Z80 before use:</p>
<blockquote>
<p><code>z80_reset(); </code></p>
</blockquote>
<p>Right, now you can run it! </p>
<p>Example: </p>
<blockquote>
<pre><code>while(running)
{
z80_emulate(4000000/60);
z80_raise_IRQ(0xff);
z80_lower_IRQ();
} </code></pre>
</blockquote>
<p><code>z80_emulate</code> will actually run the Z80. The parameter is the number
of cycles to run for. It will always execute <em>at least </em>that many cycles,
unless you deliberately cut it short during the run (see later). It will return
the number of cycles actually executed. </p>
<p><code>z80_raise_IRQ</code> will raise the IRQ line. This is the only way to
cause an interrupt in RAZE. The parameter is the value to pass on the bus. If
you're not sure, <tt>0xff</tt> is usually best. When in IM 2, you'd need to
actually provide an interrupt vector here.</p>
<ul>
<li>In IM 0, you pass the opcode to execute. Only RST opcodes are supported
currently.<br>
NOTE!: For IM 0, you would pass the opcode, not the address!<br>
(e.g. <tt>0xff</tt> instead of <tt>0x38</tt>, etc). </li>
</ul>
<p><b>You need to lower the IRQ line again!</b> Otherwise it will keep trying
to send the interrupt! This can either be done straight away, or you can execute
some cycles and then do it later. </p>
<hr>
<h2>Other functions</h2>
<p><code><strong>void z80_cause_NMI(void);</strong></code><br>
Causes an NMI immediately. Because the Z80 NMI line is edge-triggered, there
is no function to lower the line (it doesn't matter to the Z80 when it is lowered,
you see). </p>
<p><code><strong>void z80_set_fetch_callback(void (*handler)(tUWORD pc));<br>
</strong></code>This sets an opcode-fetch callback function. Every time a byte
is fetched from the instruction stream, your function will be called.</p>
<p><strong>NOTE!:</strong> For this to work, you have to edit RAZE.ASM and uncomment
this line:</p>
<blockquote>
<p><code>%define USE_FETCH_CALLBACK</code></p>
</blockquote>
<p>Your handler should be like this - (example) </p>
<blockquote>
<pre><code>void debug(tUWORD pc)
{
if (pc == 0x1234) printf("Breakpoint hit!\n");
} </code></pre>
<pre><code>z80_set_fetch_callback(&debug); </code></pre>
</blockquote>
<p><code><strong>int z80_get_cycles_elapsed(void);<br>
</strong></code>Returns the number of cycles elapsed since <code>z80_emulate</code>
was last called. </p>
<p><code><strong>void z80_stop_emulating(void);<br>
</strong></code>This can only be called from a read/write handler. It will stop
the Z80 emulating after the current instruction has completed. The cycle-count
returned from <code>z80_emulate()</code> will be less than normal, to reflect
the fact it was stopped early. </p>
<p><code><strong>void z80_skip_idle(void);<br>
</strong></code>This can only be called from a read/write handler. It will stop
the Z80 emulating after the current instruction has completed. The cycle-count
returned from <code>z80_emulate()</code> will be as though the Z80 had not been
stopped, i.e. it will be the same as normal. </p>
<p><code><strong>void z80_do_wait_states(int n);<br>
</strong></code>Temporarily halt the CPU, by stopping for 'n' T-states. This
can be called from a memory-handler, or the opcode-callback function, to reproduce
effects such as the ZX Spectrum's ULA delays, etc. </p>
<p><code><strong>tUWORD z80_get_reg(z80_register reg);<br>
</strong></code>Returns the given internal register from the Z80. If this is
called from inside a read/write handler, then only <var>Z80_REG_PC</var> can
be used. See RAZE.H for possible values. </p>
<p><code><strong>void z80_set_reg(z80_register reg, tUWORD value);<br>
</strong></code>Sets the given internal register in the Z80 to a new value.
This cannot be called from inside a read/write handler. See RAZE.H for possible
values. </p>
<p><code><strong>int z80_get_context_size(void);<br>
</strong></code>Returns the size of a RAZE context. If you need multiple Z80
emulation, you need to allocate that much memory for each context. </p>
<p><code><strong>void z80_get_context(void *context);<br>
</strong></code>Will copy the internal state of the current Z80 into the given
context. </p>
<p><code><strong>void z80_set_context(void *context);<br>
</strong></code>Will copy the given context into the internal state of the current
Z80. </p>
<h2>Misc notes:</h2>
<ul>
<li>Memory-map areas defined with <code>z80_map_fetch, z80_map_read, and z80_map_write</code>,
must start and finish aligned to a 256-byte boundary.</li>
<li>Memory-map areas must not overlap!</li>
<li>Port addresses are always 16-bit. You might have to AND them with 255.</li>
<li>The only functions callable from inside a read/write handler, are:<br>
<code>z80_map_?????, z80_raise_IRQ, z80_lower_IRQ, z80_cause_NMI,<br>
z80_get_reg(Z80_REG_PC), z80_get_cycles_elapsed, z80_stop_emulating,<br>
z80_skip_idle, z80_get_context_size.</code></li>
<li>In order to <code>z80_map_?????</code> a bit of memory, it <strong>must</strong>
be declared as in the<br>
memory map with the <code>z80_map_?????</code> functions first! (<em>not</em>
<code>z80_add_?????</code>)!<br>
Got that? Good.</li>
<li>You can speed it up a bit. Edit RAZE.ASM, remove %define's and re-compile.
</li>
</ul>
<h2>Thanks </h2>
<ul>
<li><em><strong>Ishmair</strong></em>, for MAZE, a great Z80 emulator.</li>
<li><em><strong>Charles MacDonald</strong></em><em> (cgfm2)</em>, for testing
this thing out a lot! (<a
href="http://www.emuviews.com/cgfm2/">http://www.emuviews.com/cgfm2/</a>)</li>
<li><em><strong>Sean Young</strong></em>, for his brilliant Z80 docs (<a href="http://www.msxnet.org/">http://www.msxnet.org/</a>)</li>
<li><em><strong>Frank D. Cringle</strong></em>, for ZEX. 'nuff said.</li>
<li><em><strong>Allard van der Bas</strong></em>, for the Spectrum emulator
in MAZE (<a
href="mailto:avdbas@wi.leidenuniv.nl">avdbas@wi.leidenuniv.nl</a>)</li>
<li><em><strong>Neil Bradley</strong></em>, with a good alternative to RAZE
(MZ80) (<a
href="ftp://ftp.synthcom.com/pub/emulators/cpu/makez80.zip">ftp://ftp.synthcom.com/pub/emulators/cpu/makez80.zip</a>)
</li>
</ul>
<p>I hope you can find this program useful.<br>
All comments, and bug reports are especially appreciated.</p>
<hr>
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<td>
<div align="right"><em><strong>Richard Mitton</strong></em><br>
<a href="mailto:richard.mitton@bigfoot.com">richard.mitton@bigfoot.com</a></div>
</td>
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