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1: /* AbstractDataInput.java -- 2: Copyright (C) 2005 Free Software Foundation, Inc. 3: 4: This file is part of GNU Classpath. 5: 6: GNU Classpath is free software; you can redistribute it and/or modify 7: it under the terms of the GNU General Public License as published by 8: the Free Software Foundation; either version 2, or (at your option) 9: any later version. 10: 11: GNU Classpath is distributed in the hope that it will be useful, but 12: WITHOUT ANY WARRANTY; without even the implied warranty of 13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14: General Public License for more details. 15: 16: You should have received a copy of the GNU General Public License 17: along with GNU Classpath; see the file COPYING. If not, write to the 18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 19: 02110-1301 USA. 20: 21: Linking this library statically or dynamically with other modules is 22: making a combined work based on this library. Thus, the terms and 23: conditions of the GNU General Public License cover the whole 24: combination. 25: 26: As a special exception, the copyright holders of this library give you 27: permission to link this library with independent modules to produce an 28: executable, regardless of the license terms of these independent 29: modules, and to copy and distribute the resulting executable under 30: terms of your choice, provided that you also meet, for each linked 31: independent module, the terms and conditions of the license of that 32: module. An independent module is a module which is not derived from 33: or based on this library. If you modify this library, you may extend 34: this exception to your version of the library, but you are not 35: obligated to do so. If you do not wish to do so, delete this 36: exception statement from your version. */ 37: 38: 39: package gnu.CORBA.CDR; 40: 41: import java.io.IOException; 42: 43: /** 44: * Some data input stream that can be either Big or 45: * Little Endian. 46: * 47: * This class reuses code from GNU Classpath DataInputStream. 48: * 49: * @author Audrius Meskauskas (AudriusA@Bioinformatics.org) 50: * @author Warren Levy (warrenl@cygnus.com) 51: * @author Aaron M. Renn (arenn@urbanophile.com) 52: */ 53: public interface AbstractDataInput 54: { 55: /** 56: * This method reads bytes from the underlying stream into the specified 57: * byte array buffer. It will attempt to fill the buffer completely, but 58: * may return a short count if there is insufficient data remaining to be 59: * read to fill the buffer. 60: * 61: * @param b The buffer into which bytes will be read. 62: * 63: * @return The actual number of bytes read, or -1 if end of stream reached 64: * before reading any bytes. 65: * 66: * @exception IOException If an error occurs. 67: */ 68: int read(byte[] b) 69: throws IOException; 70: 71: /** 72: * This method reads bytes from the underlying stream into the specified 73: * byte array buffer. It will attempt to read <code>len</code> bytes and 74: * will start storing them at position <code>off</code> into the buffer. 75: * This method can return a short count if there is insufficient data 76: * remaining to be read to complete the desired read length. 77: * 78: * @param b The buffer into which bytes will be read. 79: * @param off The offset into the buffer to start storing bytes. 80: * @param len The requested number of bytes to read. 81: * 82: * @return The actual number of bytes read, or -1 if end of stream reached 83: * before reading any bytes. 84: * 85: * @exception IOException If an error occurs. 86: */ 87: int read(byte[] b, int off, int len) 88: throws IOException; 89: 90: /** 91: * This method reads a Java boolean value from an input stream. It does 92: * so by reading a single byte of data. If that byte is zero, then the 93: * value returned is <code>false</code>. If the byte is non-zero, then 94: * the value returned is <code>true</code>. 95: * <p> 96: * This method can read a <code>boolean</code> written by an object 97: * implementing the <code>writeBoolean()</code> method in the 98: * <code>DataOutput</code> interface. 99: * 100: * @return The <code>boolean</code> value read 101: * 102: * @exception EOFException If end of file is reached before reading 103: * the boolean 104: * @exception IOException If any other error occurs 105: * 106: * @see DataOutput#writeBoolean 107: */ 108: boolean readBoolean() 109: throws IOException; 110: 111: /** 112: * This method reads a Java byte value from an input stream. The value 113: * is in the range of -128 to 127. 114: * <p> 115: * This method can read a <code>byte</code> written by an object 116: * implementing the <code>writeByte()</code> method in the 117: * <code>DataOutput</code> interface. 118: * 119: * @return The <code>byte</code> value read 120: * 121: * @exception EOFException If end of file is reached before reading the byte 122: * @exception IOException If any other error occurs 123: * 124: * @see DataOutput#writeByte 125: */ 126: byte readByte() 127: throws IOException; 128: 129: /** 130: * This method reads a Java <code>char</code> value from an input stream. 131: * It operates by reading two bytes from the stream and converting them to 132: * a single 16-bit Java <code>char</code>. The two bytes are stored most 133: * significant byte first (i.e., "big endian") regardless of the native 134: * host byte ordering. 135: * <p> 136: * As an example, if <code>byte1</code> and <code>byte2</code> 137: * represent the first and second byte read from the stream 138: * respectively, they will be transformed to a <code>char</code> in 139: * the following manner: 140: * <p> 141: * <code>(char)(((byte1 & 0xFF) << 8) | (byte2 & 0xFF)</code> 142: * <p> 143: * This method can read a <code>char</code> written by an object 144: * implementing the <code>writeChar()</code> method in the 145: * <code>DataOutput</code> interface. 146: * 147: * @return The <code>char</code> value read 148: * 149: * @exception EOFException If end of file is reached before reading the char 150: * @exception IOException If any other error occurs 151: * 152: * @see DataOutput#writeChar 153: */ 154: char readChar() 155: throws IOException; 156: 157: /** 158: * This method reads a Java double value from an input stream. It operates 159: * by first reading a <code>long</code> value from the stream by calling the 160: * <code>readLong()</code> method in this interface, then converts 161: * that <code>long</code> to a <code>double</code> using the 162: * <code>longBitsToDouble</code> method in the class 163: * <code>java.lang.Double</code> 164: * <p> 165: * This method can read a <code>double</code> written by an object 166: * implementing the <code>writeDouble()</code> method in the 167: * <code>DataOutput</code> interface. 168: * 169: * @return The <code>double</code> value read 170: * 171: * @exception EOFException If end of file is reached before reading 172: * the double 173: * @exception IOException If any other error occurs 174: * 175: * @see DataOutput#writeDouble 176: * @see java.lang.Double#longBitsToDouble 177: */ 178: double readDouble() 179: throws IOException; 180: 181: /** 182: * This method reads a Java float value from an input stream. It 183: * operates by first reading an <code>int</code> value from the 184: * stream by calling the <code>readInt()</code> method in this 185: * interface, then converts that <code>int</code> to a 186: * <code>float</code> using the <code>intBitsToFloat</code> method 187: * in the class <code>java.lang.Float</code> 188: * <p> 189: * This method can read a <code>float</code> written by an object 190: * implementing the <code>writeFloat()</code> method in the 191: * <code>DataOutput</code> interface. 192: * 193: * @return The <code>float</code> value read 194: * 195: * @exception EOFException If end of file is reached before reading the float 196: * @exception IOException If any other error occurs 197: * 198: * @see DataOutput#writeFloat 199: * @see java.lang.Float#intBitsToFloat 200: */ 201: float readFloat() 202: throws IOException; 203: 204: /** 205: * This method reads raw bytes into the passed array until the array is 206: * full. Note that this method blocks until the data is available and 207: * throws an exception if there is not enough data left in the stream to 208: * fill the buffer. Note also that zero length buffers are permitted. 209: * In this case, the method will return immediately without reading any 210: * bytes from the stream. 211: * 212: * @param b The buffer into which to read the data 213: * 214: * @exception EOFException If end of file is reached before filling the 215: * buffer 216: * @exception IOException If any other error occurs 217: */ 218: void readFully(byte[] b) 219: throws IOException; 220: 221: /** 222: * This method reads a Java <code>int</code> value from an input stream 223: * It operates by reading four bytes from the stream and converting them to 224: * a single Java <code>int</code>. The bytes are stored most 225: * significant byte first (i.e., "big endian") regardless of the native 226: * host byte ordering. 227: * <p> 228: * As an example, if <code>byte1</code> through <code>byte4</code> represent 229: * the first four bytes read from the stream, they will be 230: * transformed to an <code>int</code> in the following manner: 231: * <p> 232: * <code>(int)(((byte1 & 0xFF) << 24) + ((byte2 & 0xFF) << 16) + 233: * ((byte3 & 0xFF)<< 8) + (byte4 & 0xFF)))</code> 234: * <p> 235: * The value returned is in the range of -2147483648 to 2147483647. 236: * <p> 237: * This method can read an <code>int</code> written by an object 238: * implementing the <code>writeInt()</code> method in the 239: * <code>DataOutput</code> interface. 240: * 241: * @return The <code>int</code> value read 242: * 243: * @exception EOFException If end of file is reached before reading the int 244: * @exception IOException If any other error occurs 245: * 246: * @see DataOutput#writeInt 247: */ 248: int readInt() 249: throws IOException; 250: 251: /** 252: * This method reads a Java <code>long</code> value from an input stream 253: * It operates by reading eight bytes from the stream and converting them to 254: * a single Java <code>long</code>. The bytes are stored most 255: * significant byte first (i.e., "big endian") regardless of the native 256: * host byte ordering. 257: * <p> 258: * As an example, if <code>byte1</code> through <code>byte8</code> represent 259: * the first eight bytes read from the stream, they will be 260: * transformed to an <code>long</code> in the following manner: 261: * <p> 262: * <code>(long)(((byte1 & 0xFF) << 56) + ((byte2 & 0xFF) << 48) + 263: * ((byte3 & 0xFF) << 40) + ((byte4 & 0xFF) << 32) + 264: * ((byte5 & 0xFF) << 24) + ((byte6 & 0xFF) << 16) + 265: * ((byte7 & 0xFF) << 8) + (byte8 & 0xFF))) 266: * </code> 267: * <p> 268: * The value returned is in the range of -9223372036854775808 to 269: * 9223372036854775807. 270: * <p> 271: * This method can read an <code>long</code> written by an object 272: * implementing the <code>writeLong()</code> method in the 273: * <code>DataOutput</code> interface. 274: * 275: * @return The <code>long</code> value read 276: * 277: * @exception EOFException If end of file is reached before reading the long 278: * @exception IOException If any other error occurs 279: * 280: * @see DataOutput#writeLong 281: */ 282: long readLong() 283: throws IOException; 284: 285: /** 286: * This method reads a signed 16-bit value into a Java in from the 287: * stream. It operates by reading two bytes from the stream and 288: * converting them to a single 16-bit Java <code>short</code>. The 289: * two bytes are stored most significant byte first (i.e., "big 290: * endian") regardless of the native host byte ordering. 291: * <p> 292: * As an example, if <code>byte1</code> and <code>byte2</code> 293: * represent the first and second byte read from the stream 294: * respectively, they will be transformed to a <code>short</code>. in 295: * the following manner: 296: * <p> 297: * <code>(short)(((byte1 & 0xFF) << 8) | (byte2 & 0xFF))</code> 298: * <p> 299: * The value returned is in the range of -32768 to 32767. 300: * <p> 301: * This method can read a <code>short</code> written by an object 302: * implementing the <code>writeShort()</code> method in the 303: * <code>DataOutput</code> interface. 304: * 305: * @return The <code>short</code> value read 306: * 307: * @exception EOFException If end of file is reached before reading the value 308: * @exception IOException If any other error occurs 309: * 310: * @see DataOutput#writeShort 311: */ 312: short readShort() 313: throws IOException; 314: 315: /** 316: * This method reads 8 unsigned bits into a Java <code>int</code> 317: * value from the stream. The value returned is in the range of 0 to 318: * 255. 319: * <p> 320: * This method can read an unsigned byte written by an object 321: * implementing the <code>writeUnsignedByte()</code> method in the 322: * <code>DataOutput</code> interface. 323: * 324: * @return The unsigned bytes value read as a Java <code>int</code>. 325: * 326: * @exception EOFException If end of file is reached before reading the value 327: * @exception IOException If any other error occurs 328: * 329: * @see DataOutput#writeByte 330: */ 331: int readUnsignedByte() 332: throws IOException; 333: 334: /** 335: * This method reads 16 unsigned bits into a Java int value from the stream. 336: * It operates by reading two bytes from the stream and converting them to 337: * a single Java <code>int</code> The two bytes are stored most 338: * significant byte first (i.e., "big endian") regardless of the native 339: * host byte ordering. 340: * <p> 341: * As an example, if <code>byte1</code> and <code>byte2</code> 342: * represent the first and second byte read from the stream 343: * respectively, they will be transformed to an <code>int</code> in 344: * the following manner: 345: * <p> 346: * <code>(int)(((byte1 & 0xFF) << 8) + (byte2 & 0xFF))</code> 347: * <p> 348: * The value returned is in the range of 0 to 65535. 349: * <p> 350: * This method can read an unsigned short written by an object 351: * implementing the <code>writeUnsignedShort()</code> method in the 352: * <code>DataOutput</code> interface. 353: * 354: * @return The unsigned short value read as a Java <code>int</code> 355: * 356: * @exception EOFException If end of file is reached before reading the value 357: * @exception IOException If any other error occurs 358: * 359: * @see DataOutput#writeShort 360: */ 361: int readUnsignedShort() 362: throws IOException; 363: 364: /** 365: * Read a single byte. 366: * 367: * @return a byte, extracted from the stream or -1 if 368: * EOF has been reached. 369: * @throws IOException 370: */ 371: public int read() 372: throws IOException; 373: 374: /** 375: * This method attempts to skip and discard the specified number of bytes 376: * in the input stream. It may actually skip fewer bytes than requested. 377: * This method will not skip any bytes if passed a negative number of bytes 378: * to skip. 379: * 380: * @param n The requested number of bytes to skip. 381: * 382: * @return The requested number of bytes to skip. 383: * 384: * @exception IOException If an error occurs. 385: * @specnote The JDK docs claim that this returns the number of bytes 386: * actually skipped. The JCL claims that this method can throw an 387: * EOFException. Neither of these appear to be true in the JDK 1.3's 388: * implementation. This tries to implement the actual JDK behaviour. 389: */ 390: int skipBytes(int n) 391: throws IOException; 392: }