ref: dc390e8c1f6e37797e7c852637259b56c481a416
dir: /doc/asm/trg_gb.htm/
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html;charset=UTF-8">
<title>xAsm Gameboy</title>
<link rel="stylesheet" type="text/css" href="../style.css">
</head>
<body>
<h1>Gameboy</h1>
<p>The full GB-Z80 instruction-set is implemented with a few modifications to the original Zilog syntax. This is due to a Bison problem but in my opinion the syntax is better than the original one.</p>
<h2>Instructions</h2>
<ul>
<li>ADC
<li>ADD
<li>AND
<li>BIT
<li>CALL
<li>CCF
<li>CP
<li>CPL
<li>DAA
<li>DEC
<li>DI
<li>EI
<li>EX
<li>HALT
<li>INC
<li>JP
<li>JR
<li>LD
<li>LDD
<li>LDI
<li>LDH/LDIO (see note below)
<li>NOP
<li>OR
<li>POP
<li>PUSH
<li>RES
<li>RET
<li>RETI
<li>RL
<li>RLA
<li>RLC
<li>RLCA
<li>RR
<li>RRA
<li>RRC
<li>RRCA
<li>RST
<li>SBC
<li>SCF
<li>SET
<li>SLA
<li>SRA
<li>SRL
<li>STOP
<li>SUB
<li>SWAP
<li>XOR
</ul>
<p>Note that you can use both
<pre> OR A,B
OR B</pre>
<h2>Addressingmodes</h2>
<p>Indirect addressing has been changed to [ ] instead of ( ):</p>
<ul>
<li> A
<li> B
<li> C
<li> D
<li> E
<li> H
<li> L
<li> AF
<li> BC
<li> DE
<li> HL
<li> SP
<li> [BC]
<li> [DE]
<li> [HL]
<li> [HL-]/[HLI]
<li> [HL+]/[HLD]
<li> [SP]
<li> n8 (8 bit expression)
<li> n16 (16 bit expression)
<li> n3 (3 bit CONSTANT expression)
<li> [n16]/[$FF00+n8]
<li> [$FF00+C]/[C]
</ul>
<p>The assembler will intelligently decide between <b>[n16]</b> and <b>[$FF00+n8]</b> in the LD instruction. Note however that if you use any <a href="symbols.htm">constant symbols</a> in the expression they had better be defined before the instruction or your symbol-table may become mangled. Also worth noting is that it will only ever select the short $FF00 mode when you use constant symbols. NOT if you use symbols defined in a <a href="section.htm">HRAM section</a>. As this defies the whole point of implementing the HRAM sectiontype I've added the LDIO mnemonic. It works like the LD instruction but it will ALWAYS generate the $FF00+ form and it will also automatically logically AND the expression with $FF if it is relocatable. Which is what you want. Trust me ;)</p>
<h2>Conditioncodes</h2>
<ul>
<li> C
<li> NC
<li> Z
<li> NZ
</ul>
<hr>
<p>Last updated 20 July 1997 by <a href="mailto:[email protected]">Carsten Sorensen</a></p>
</body>
</html>