modules/cldc-compact/src/main/java/cc/squirreljme/jvm/pack/HeaderStruct.java

   1 // -*- Mode: Java; indent-tabs-mode: t; tab-width: 4 -*-
   2 // ---------------------------------------------------------------------------
   3 // Multi-Phasic Applications: SquirrelJME
   4 //     Copyright (C) Stephanie Gawroriski <xer@multiphasicapps.net>
   5 // ---------------------------------------------------------------------------
   6 // SquirrelJME is under the GNU General Public License v3+, or later.
   7 // See license.mkd for licensing and copyright information.
   8 // ---------------------------------------------------------------------------
   9
  10 package cc.squirreljme.jvm.pack;
  11
  12 import cc.squirreljme.jvm.pack.constants.ClassInfoConstants;
  13 import cc.squirreljme.runtime.cldc.annotation.Exported;
  14 import java.io.DataInput;
  15 import java.io.IOException;
  16
  17 /**
  18  * Common header structure that is shared for all ROM formats.
  19  *
  20  * @since 2021/04/07
  21  */
  22 @Exported
  23 public final class HeaderStruct
  24 {
  25         /** The ROM Magic Number. */
  26         protected final int magicNumber;
  27
  28         /** The format version. */
  29         protected final int formatVersion;
  30
  31         /** The properties used. */
  32         private final int[] _properties;
  33
  34         /**
  35          * Initializes the header structure.
  36          *
  37          * @param __romMagic The ROM Magic number.
  38          * @param __formatVersion The format version.
  39          * @param __properties The properties used.
  40          * @throws NullPointerException On null arguments.
  41          * @since 2021/04/07
  42          */
  43         private HeaderStruct(int __romMagic, int __formatVersion,
  44                 int[] __properties)
  45                 throws NullPointerException
  46         {
  47                 if (__properties == null)
  48                         throw new NullPointerException("NARG");
  49
  50                 this.magicNumber = __romMagic;
  51                 this.formatVersion = __formatVersion;
  52                 this._properties = __properties;
  53         }
  54
  55         /**
  56          * Obtains the given property.
  57          *
  58          * @param __prop The property to get.
  59          * @return The value of the given property.
  60          * @throws IndexOutOfBoundsException If the property is not within bounds.
  61          * @since 2021/04/07
  62          */
  63         @Exported
  64         public int getInteger(int __prop)
  65                 throws IndexOutOfBoundsException
  66         {
  67                 // {@squirreljme.error ZZ55 Invalid property. (The property)}
  68                 int[] properties = this._properties;
  69                 if (__prop < 0 || __prop >= properties.length)
  70                         throw new IndexOutOfBoundsException("ZZ55 " + __prop);
  71
  72                 return properties[__prop];
  73         }
  74
  75         /**
  76          * Gets the long valued property.
  77          *
  78          * @param __prop The property to get, the low value is first while the
  79          * high value is the next property.
  80          * @return The long value.
  81          * @throws IndexOutOfBoundsException If the property is not within bounds.
  82          * @since 2021/07/13
  83          */
  84         @Exported
  85         @SuppressWarnings("MagicNumber")
  86         public long getLong(int __prop)
  87                 throws IndexOutOfBoundsException
  88         {
  89                 return (this.getInteger(__prop) & 0xFFFFFFFFL) |
  90                         ((long)this.getInteger(__prop) << 32);
  91         }
  92
  93         /**
  94          * Returns the magic number of the structure.
  95          *
  96          * @return The structure's magic number.
  97          * @since 2021/07/11
  98          */
  99         @Exported
 100         public int magicNumber()
 101         {
 102                 return this.magicNumber;
 103         }
 104
 105         /**
 106          * Returns the number of properties.
 107          *
 108          * @return The number of properties.
 109          * @since 2021/05/16
 110          */
 111         @Exported
 112         public final int numProperties()
 113         {
 114                 return this._properties.length;
 115         }
 116
 117         /**
 118          * Decodes the header.
 119          *
 120          * @param __in The input to decode from.
 121          * @param __maxProps The maximum number of valid properties.
 122          * @return The header structure.
 123          * @throws IOException On read errors.
 124          * @since 2021/04/07
 125          */
 126         @Exported
 127         public static HeaderStruct decode(DataInput __in, int __maxProps)
 128                 throws IOException
 129         {
 130                 // Read the magic number
 131                 int romMagic = __in.readInt();
 132
 133                 // Read the format version
 134                 int formatVersion = __in.readUnsignedShort();
 135
 136                 // {@squirreljme.error ZZ44 Cannot decode header because the
 137                 // version identifier is not known. (The format version of the header
 138                 // file)}
 139                 if (formatVersion != ClassInfoConstants.CLASS_VERSION_20201129)
 140                         throw new InvalidRomException("ZZ44 " + formatVersion);
 141
 142                 // Read in all the data
 143                 int numProperties = Math.min(__in.readUnsignedShort(), __maxProps);
 144                 int[] properties = new int[numProperties];
 145                 for (int i = 0; i < numProperties; i++)
 146                         properties[i] = __in.readInt();
 147
 148                 return new HeaderStruct(romMagic, formatVersion, properties);
 149         }
 150 }