SSE Level 2 Vendor Interface Specification(FAST)-15章-FAST Decoder（FAST解析-第三部分）

15.5 Transfer encoding

>>>傳輸編碼
The stop-bit and presence map are used in transfer encoding.

>>>stop-bit 和presence map 在傳輸編碼中被使用.
 
15.5.1 Stop bit

>>>停止位
Stop bit is using the high order bit of each type to indicate whether this byte is the final byte for
representing a value. If the high order bit is ‘1’, it is the final byte for representing this value.
However, for byte vector data type and UTF-8 String cannot use stop bit as the data contained in these
two types is binary.  It is costly to use stop bit, so an unsigned integer length field is added before
these two types.

>>>stop-bit 使用每一個類型的高階位來指示這個byte是否是表現值的最後byte.如果高階位是'1',則它是表現值的最後byte.

>>>無論如何,對於byte vector數據類型和UTF-8 String不能使用stop-bit ,因爲這兩種類型所包含的數據是二進制的.

>>>使用stop-bit 是昂貴的,所以在這兩種類型前增加一個無符號整形的長度字段.

 

15.5.1.1  String data type

>>>String數據類型
String data type is used for storing ASCII String fields. ASCII is represented by one or more bytes
with 7 significant data bits per byte. So that, the high order bit can be used as stop bit.
>>>String數據類型用於存儲ASCII String字段.ASCII是通過一個或多個bytes來呈現的,每個byte使用7個有效數據位.

>>>所以,高階位能用來當stop-bit .

 

Here is the example for String data type:

>>>String數據類型的例子:

 
15.5.1.2  Signed integer data type

 

>>>有符號整型
A signed integer data type is used for the two’s complement integer representation. The high order bit
can be used as stop bit and the most significant data bit of the first bye is a sign bit.

>>>

 

Here is the example for Signed integer data type:

 

>>>有符號整型的例子:

 

 >>>如果這個字段是可選的並且是一個正數,則遞增1.

 

 

15.5.1.3  Byte vector data type

>>>Byte vector數據類型
Byte vector data type is used for storing binary data. The stop bit approach is not used and there is a
signed integer length field is added before the binary data.

>>>Byte vector數據類型用於存儲二進制數據.停止位的方法是不被使用的,並且在二進制數據之前增加了一個有符號整型長度字段.

 

15.5.1.4  Signed long data type

>>>有符號長整型
A signed long data type is used for the two’s complement long representation. The high order bit can
be used as stop bit and the most significant data bit of the first bye is a sign bit.

>>>
 
Here is the example for Signed long data type:

>>>有符號長整型的例子:

>>>如果這個字段是可選的並且是一個正數,則遞增1. 

 

15.5.1.5  UTF-8 String data type

>>>UTF-8 String
UTF-8 String data type is used for storing UTF-8 String data. The stop bit approach is not used and
there is a signed integer length field is added before the binary data.

>>>UTF-8 String用於存儲UTF-8 String數據.stop bit 的方法是不被使用的,並且在二進制數據之前增加了一個有符號整型長度字段.

 

 

SSE Level 2 Vendor Interface Specification(FAST)-15章-FAST Decoder（FAST解析-第三部分）--完