| 1 | /* |
| 2 | |
| 3 | Derby - Class org.apache.derby.iapi.services.io.FormatIdUtil |
| 4 | |
| 5 | Copyright 1997, 2004 The Apache Software Foundation or its licensors, as applicable. |
| 6 | |
| 7 | Licensed under the Apache License, Version 2.0 (the "License"); |
| 8 | you may not use this file except in compliance with the License. |
| 9 | You may obtain a copy of the License at |
| 10 | |
| 11 | http://www.apache.org/licenses/LICENSE-2.0 |
| 12 | |
| 13 | Unless required by applicable law or agreed to in writing, software |
| 14 | distributed under the License is distributed on an "AS IS" BASIS, |
| 15 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 16 | See the License for the specific language governing permissions and |
| 17 | limitations under the License. |
| 18 | |
| 19 | */ |
| 20 | |
| 21 | package org.apache.derby.iapi.services.io; |
| 22 | |
| 23 | import java.io.DataInput; |
| 24 | import java.io.DataOutput; |
| 25 | import java.io.IOException; |
| 26 | |
| 27 | /** |
| 28 | Utility class with static methods for constructing and reading the byte array |
| 29 | representation of format id's. |
| 30 | |
| 31 | <P>This utility supports a number of families of format ids. The byte array |
| 32 | form of each family is a different length. In all cases the first two bits |
| 33 | of the first byte indicate the family for an id. The list below describes |
| 34 | each family and gives its two bit identifier in parens. |
| 35 | |
| 36 | <UL> |
| 37 | <LI> (0) - The format id is a one byte number between 0 and 63 inclusive. |
| 38 | The byte[] encoding fits in one byte. |
| 39 | <LI> (1) - The format id is a two byte number between 16384 to 32767 |
| 40 | inclusive. The byte[] encoding stores the high order byte |
| 41 | first. |
| 42 | <LI> (2) - The format id is four byte number between 2147483648 and |
| 43 | 3221225471 inclusive. The byte[] encoding stores the high |
| 44 | order byte first. |
| 45 | <LI> (3) - Future expansion. |
| 46 | </UL> |
| 47 | */ |
| 48 | public final class FormatIdUtil |
| 49 | { |
| 50 | private FormatIdUtil() { |
| 51 | } |
| 52 | |
| 53 | public static int getFormatIdByteLength(int formatId) { |
| 54 | return 2; |
| 55 | } |
| 56 | |
| 57 | public static void writeFormatIdInteger(DataOutput out, int formatId) throws IOException { |
| 58 | out.writeShort(formatId); |
| 59 | } |
| 60 | |
| 61 | public static int readFormatIdInteger(DataInput in) |
| 62 | throws IOException { |
| 63 | |
| 64 | return in.readUnsignedShort(); |
| 65 | } |
| 66 | |
| 67 | public static int readFormatIdInteger(byte[] data) { |
| 68 | |
| 69 | int a = data[0]; |
| 70 | int b = data[1]; |
| 71 | return (((a & 0xff) << 8) | (b & 0xff)); |
| 72 | } |
| 73 | |
| 74 | public static String formatIdToString(int fmtId) { |
| 75 | |
| 76 | return Integer.toString(fmtId); |
| 77 | } |
| 78 | } |