checkin for entire port source tree

port_src/output/zxing/common/bit_source.rs

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+/*
+ * Copyright 2007 ZXing authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+// package com::google::zxing::common;
+
+/**
+ * <p>This provides an easy abstraction to read bits at a time from a sequence of bytes, where the
+ * number of bits read is not often a multiple of 8.</p>
+ *
+ * <p>This class is thread-safe but not reentrant -- unless the caller modifies the bytes array
+ * it passed in, in which case all bets are off.</p>
+ *
+ * @author Sean Owen
+ */
+pub struct BitSource {
+
+     let bytes: Vec<i8>;
+
+     let byte_offset: i32;
+
+     let bit_offset: i32;
+}
+
+impl BitSource {
+
+    /**
+   * @param bytes bytes from which this will read bits. Bits will be read from the first byte first.
+   * Bits are read within a byte from most-significant to least-significant bit.
+   */
+    pub fn new( bytes: &Vec<i8>) -> BitSource {
+        let .bytes = bytes;
+    }
+
+    /**
+   * @return index of next bit in current byte which would be read by the next call to {@link #readBits(int)}.
+   */
+    pub fn  get_bit_offset(&self) -> i32  {
+        return self.bit_offset;
+    }
+
+    /**
+   * @return index of next byte in input byte array which would be read by the next call to {@link #readBits(int)}.
+   */
+    pub fn  get_byte_offset(&self) -> i32  {
+        return self.byte_offset;
+    }
+
+    /**
+   * @param numBits number of bits to read
+   * @return int representing the bits read. The bits will appear as the least-significant
+   *         bits of the int
+   * @throws IllegalArgumentException if numBits isn't in [1,32] or more than is available
+   */
+    pub fn  read_bits(&self,  num_bits: i32) -> i32  {
+        if num_bits < 1 || num_bits > 32 || num_bits > self.available() {
+            throw IllegalArgumentException::new(&String::value_of(num_bits));
+        }
+         let mut result: i32 = 0;
+        // First, read remainder from current byte
+        if self.bit_offset > 0 {
+             let bits_left: i32 = 8 - self.bit_offset;
+             let to_read: i32 = Math::min(num_bits, bits_left);
+             let bits_to_not_read: i32 = bits_left - to_read;
+             let mask: i32 = (0xFF >> (8 - to_read)) << bits_to_not_read;
+            result = (self.bytes[self.byte_offset] & mask) >> bits_to_not_read;
+            num_bits -= to_read;
+            self.bit_offset += to_read;
+            if self.bit_offset == 8 {
+                self.bit_offset = 0;
+                self.byte_offset += 1;
+            }
+        }
+        // Next read whole bytes
+        if num_bits > 0 {
+            while num_bits >= 8 {
+                result = (result << 8) | (self.bytes[self.byte_offset] & 0xFF);
+                self.byte_offset += 1;
+                num_bits -= 8;
+            }
+            // Finally read a partial byte
+            if num_bits > 0 {
+                 let bits_to_not_read: i32 = 8 - num_bits;
+                 let mask: i32 = (0xFF >> bits_to_not_read) << bits_to_not_read;
+                result = (result << num_bits) | ((self.bytes[self.byte_offset] & mask) >> bits_to_not_read);
+                self.bit_offset += num_bits;
+            }
+        }
+        return result;
+    }
+
+    /**
+   * @return number of bits that can be read successfully
+   */
+    pub fn  available(&self) -> i32  {
+        return 8 * (self.bytes.len() - self.byte_offset) - self.bit_offset;
+    }
+}
+