-/*\r
-* Copyright 2008 ZXing authors\r
+/*\r
+* Copyright 2007 ZXing authors\r
*\r
* Licensed under the Apache License, Version 2.0 (the "License");\r
* you may not use this file except in compliance with the License.\r
* See the License for the specific language governing permissions and\r
* limitations under the License.\r
*/\r
+using System;\r
namespace com.google.zxing.common\r
{\r
- using System;\r
- using System.Text;\r
-\r
- /// <summary> A class which wraps a 2D array of bytes. The default usage is signed. If you want to use it as a\r
- /// unsigned container, it's up to you to do byteValue & 0xff at each location.\r
- /// *\r
- /// JAVAPORT: I'm not happy about the argument ordering throughout the file, as I always like to have\r
- /// the horizontal component first, but this is for compatibility with the C++ code. The original\r
- /// code was a 2D array of ints, but since it only ever gets assigned -1, 0, and 1, I'm going to use\r
- /// less memory and go with bytes.\r
- /// *\r
- /// </summary>\r
- /// <author> dswitkin@google.com (Daniel Switkin)\r
- /// \r
- /// </author>\r
- public sealed class BitSource\r
- { \r
- private sbyte[] bytes;\r
- private int byteOffset;\r
- private int bitOffset;\r
-\r
- /**\r
- * @param bytes bytes from which this will read bits. Bits will be read from the first byte first.\r
- * Bits are read within a byte from most-significant to least-significant bit.\r
- */\r
- public BitSource(sbyte[] bytes) {\r
- this.bytes = bytes;\r
- }\r
-\r
- /**\r
- * @param numBits number of bits to read\r
- * @return int representing the bits read. The bits will appear as the least-significant\r
- * bits of the int\r
- * @throws IllegalArgumentException if numBits isn't in [1,32]\r
- */\r
- public int readBits(int numBits) {\r
- if (numBits < 1 || numBits > 32) {\r
- throw new Exception();\r
- }\r
-\r
- int result = 0;\r
-\r
- // First, read remainder from current byte\r
- if (bitOffset > 0) {\r
- int bitsLeft = 8 - bitOffset;\r
- int toRead = numBits < bitsLeft ? numBits : bitsLeft;\r
- int bitsToNotRead = bitsLeft - toRead;\r
- int mask = (0xFF >> (8 - toRead)) << bitsToNotRead;\r
- result = (bytes[byteOffset] & mask) >> bitsToNotRead;\r
- numBits -= toRead;\r
- bitOffset += toRead;\r
- if (bitOffset == 8) {\r
- bitOffset = 0;\r
- byteOffset++;\r
- }\r
- }\r
-\r
- // Next read whole bytes\r
- if (numBits > 0) {\r
- while (numBits >= 8) {\r
- result = (result << 8) | (bytes[byteOffset] & 0xFF);\r
- byteOffset++;\r
- numBits -= 8;\r
- }\r
-\r
- // Finally read a partial byte\r
- if (numBits > 0) {\r
- int bitsToNotRead = 8 - numBits;\r
- int mask = (0xFF >> bitsToNotRead) << bitsToNotRead;\r
- result = (result << numBits) | ((bytes[byteOffset] & mask) >> bitsToNotRead);\r
- bitOffset += numBits;\r
- }\r
- }\r
-\r
- return result;\r
- }\r
-\r
- /**\r
- * @return number of bits that can be read successfully\r
- */\r
- public int available() {\r
- return 8 * (bytes.Length - byteOffset) - bitOffset;\r
- }\r
- }\r
+ \r
+ /// <summary> <p>This provides an easy abstraction to read bits at a time from a sequence of bytes, where the\r
+ /// number of bits read is not often a multiple of 8.</p>\r
+ /// \r
+ /// <p>This class is thread-safe but not reentrant. Unless the caller modifies the bytes array\r
+ /// it passed in, in which case all bets are off.</p>\r
+ /// \r
+ /// </summary>\r
+ /// <author> Sean Owen\r
+ /// </author>\r
+ /// <author>www.Redivivus.in (suraj.supekar@redivivus.in) - Ported from ZXING Java Source \r
+ /// </author>\r
+ public sealed class BitSource\r
+ {\r
+ \r
+ //UPGRADE_NOTE: Final was removed from the declaration of 'bytes '. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1003'"\r
+ private sbyte[] bytes;\r
+ private int byteOffset;\r
+ private int bitOffset;\r
+ \r
+ /// <param name="bytes">bytes from which this will read bits. Bits will be read from the first byte first.\r
+ /// Bits are read within a byte from most-significant to least-significant bit.\r
+ /// </param>\r
+ public BitSource(sbyte[] bytes)\r
+ {\r
+ this.bytes = bytes;\r
+ }\r
+ \r
+ /// <param name="numBits">number of bits to read\r
+ /// </param>\r
+ /// <returns> int representing the bits read. The bits will appear as the least-significant\r
+ /// bits of the int\r
+ /// </returns>\r
+ /// <throws> IllegalArgumentException if numBits isn't in [1,32] </throws>\r
+ public int readBits(int numBits)\r
+ {\r
+ if (numBits < 1 || numBits > 32)\r
+ {\r
+ throw new System.ArgumentException();\r
+ }\r
+ \r
+ int result = 0;\r
+ \r
+ // First, read remainder from current byte\r
+ if (bitOffset > 0)\r
+ {\r
+ int bitsLeft = 8 - bitOffset;\r
+ int toRead = numBits < bitsLeft?numBits:bitsLeft;\r
+ int bitsToNotRead = bitsLeft - toRead;\r
+ int mask = (0xFF >> (8 - toRead)) << bitsToNotRead;\r
+ result = (bytes[byteOffset] & mask) >> bitsToNotRead;\r
+ numBits -= toRead;\r
+ bitOffset += toRead;\r
+ if (bitOffset == 8)\r
+ {\r
+ bitOffset = 0;\r
+ byteOffset++;\r
+ }\r
+ }\r
+ \r
+ // Next read whole bytes\r
+ if (numBits > 0)\r
+ {\r
+ while (numBits >= 8)\r
+ {\r
+ result = (result << 8) | (bytes[byteOffset] & 0xFF);\r
+ byteOffset++;\r
+ numBits -= 8;\r
+ }\r
+ \r
+ // Finally read a partial byte\r
+ if (numBits > 0)\r
+ {\r
+ int bitsToNotRead = 8 - numBits;\r
+ int mask = (0xFF >> bitsToNotRead) << bitsToNotRead;\r
+ result = (result << numBits) | ((bytes[byteOffset] & mask) >> bitsToNotRead);\r
+ bitOffset += numBits;\r
+ }\r
+ }\r
+ \r
+ return result;\r
+ }\r
+ \r
+ /// <returns> number of bits that can be read successfully\r
+ /// </returns>\r
+ public int available()\r
+ {\r
+ return 8 * (bytes.Length - byteOffset) - bitOffset;\r
+ }\r
+ }\r
}
\ No newline at end of file
projects / zxing.git / blobdiff