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[Expression of run length]

Normal run length (matching sequence length) is expressed as a positive number, and non-matching sequence length is expressed as a negative number. Since the run length (matching sequence length) is always 2 or more, describe the value by subtracting 2.
The number of bytes used to express the run length is the same as the number of processing unit bytes.
* The actual amount of data for the run length is interpreted in terms of processing units. In other words, if the processing unit is WORD and the run length is 5, it means encoding processing for 10-byte data.
The following table shows the range of run length values ​​that can be expressed.

Table 1.2 Run length and run length expression 
 
 
 Processing unit 
 Run length (matching sequence length) 
 mismatch sequence length 
 Expression (description) 
 Expression (description) 
 BYTE1 byte 
 WORD2 bytes 
 DWORD4 bytes

[Image of processing]

The following figure shows the image of the compression algorithm using run length / mismatch sequence processing.

Figure 1.2 Run length / mismatch sequence processing

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