Home WTI User's Guides
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1. Introduction
2. Binary Block Read Mode and Structure
2.1. Compressed Binary Block Read Sequence
2.2. Compressed Binary Block Structure
2.2.1. Data Block Structure
2.2.2. Record String Structure
3. Compression Decompression Methods
3.1. Table Decompression
3.1.1. Nibble Positioning
3.1.2. Record String Format
3.1.2.1. Data Decompression Considerations
3.1.3. Table Decompression Example
3.2. Space Compression
4. DLE Stuffing
5. The Cyclic Redundancy Check Option
5.1. Calculation
6. Other Binary Read Commands
6.1. Continuous Binary Block Read
6.2. Send Binary Information Block
7. Customer Service
PollCat NetLink B

3.1.3. Table Decompression Example

 

Figure 6: Table Decompression Example

1. Offset byte shows 14 bytes in the record string. Subtracting 3 bytes for the header leaves 11 compressed bytes.

2. The mode byte shows table compression but no space decompression.

3. Character count shows 15 original characters before any decompression.

4. Starting with LSN of the first byte, the offsets and literals are read as follows. Note that the last nibble (MSN of Data-11) is ignored (a "$" indicates a literal HEX character).

12345AAAAA$41 $42 $43DE

5. When the offsets are replaced with their ASCII values from the compression table, and the literal HEX values are converted to ASCII, the following string of characters results:

 

ASCII string = 12345 ABC <CR><LF>