| // Copyright (C) 2014 The Android Open Source Project |
| // |
| // 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 binary implements encoding and decoding of various primitive |
| // data types to and from a binary stream. The package holds BitStream for packing and unpacking |
| // sequences of bits, Float16 for dealing with 16 bit floating-point values and Encoder/Decoder for |
| // encoding and decoding various value types to a binary stream. |
| // |
| // Encoding details |
| // |
| // binary.Encoder and binary.Decoder provide a symmetrical pair of methods for encoding and decoding |
| // various data types to a binary stream. For performance reasons, each data type has a separate |
| // method for encoding and decoding rather than having a single pair of methods encoding and |
| // decoding boxed values in an interface{}. The binary format has been intentionally kept simple, |
| // with a preference for simplicity over compactness. |
| // |
| // Boolean values are encoded as single bytes, where 0 represents false and non-zero represents |
| // true. |
| // |
| // Integer values are encoded as little-endian words, with no compression or alignment. For example |
| // a 16 bit unsigned integer would be encoded as two bytes, the first containing the |
| // least-significant portion of the word. |
| // |
| // 32 bit floating-point numbers are first converted to a 32 bit unsigned integer using |
| // math.Float32bits before being encoded as described above. |
| // |
| // 64 bit floating-point numbers are first converted to a 64 bit unsigned integer using |
| // math.Float64bits before being encoded as described above. |
| // |
| // Strings values can be encoded in two different formats, either with String or CString. |
| // |
| // String encodes a 32 bit unsigned integer representing the length of the string in bytes followed |
| // by the string data encoded in UTF-8: |
| // count uint32 // in bytes |
| // data0, data1, data2... byte // string in UTF-8 |
| // |
| // CString encodes the UTF-8 encoded string data terminated with a single 0 byte: |
| // data0, data1, data2... byte // string in UTF-8 |
| // term byte // 0x00 |
| // |
| // Binary blobs are encoded using the Data method as a 32 bit unsigned integers representing the |
| // number of bytes followed by the sequence of data bytes: |
| // count uint32 // in bytes |
| // data0, data1, data2... byte // blob data |
| // |
| // Objects are encoded in three different forms, depending on whether the object was nil, or was |
| // already encoded to the stream. If the object is non-nil and is encoded for the first time for a |
| // given Encoder then the object is encoded as: |
| // key uint16 // A unique identifier for the object instance. Valid range: [0x0000, 0xfffe] |
| // type uint16 // A unique identifier for the type of the object |
| // ...data... // The object's data (length dependent on the object type) |
| // |
| // All subsequent encodings of the object are encoded as the 16 bit key identifier without any |
| // additional data: |
| // key uint16 // An identifier of a previously encoded object instance |
| // |
| // If the object is nil, then the object is encoded as the 16 bit unsigned integer 0xffff without |
| // any additional data. |
| // |
| package binary |
