Data compression apparatus and method

• US 5,414,425 A
• Filed: 05/09/1994
• Issued: 05/09/1995
• Est. Priority Date: 01/13/1989
• Status: Expired due to Fees

• Current Assignee: Hifn, Inc. (Maxlinear Incorporated)
• Original Assignee: Stac, Inc. (Titan Corporation)
• Inventors: Whiting, Douglas L., Ivey, Glen E., George, Glen A.
• Primary Examiner(s): Logan, Sharon D.
• Application Number:
  US08/240,960
• Time in Patent Office: 365 Days
• Field of Search: 341/67, 341/106, 341/95, 341/66, 341/65, 341/50
• US Class Current: 341/67
• CPC Class Codes: G06T 9/005 Statistical coding, e.g. Huffman, run length coding
• CPC Class Codes: H03M 7/3086 employing a sliding window, e.g. LZ77
• CPC Class Codes: H03M 7/40 Conversion to or from variable length codes, e.g. Shannon-Fano code, Huffman code, Morse code
• CPC Class Codes: H03M 7/46 Conversion to or from run-length codes, i.e. by representing the number of consecutive digits, or groups of digits, of the same kind by a code word and a digit indicative of that kind

Abstract

An apparatus and method are disclosed for converting an input data character stream into a variable length encoded data stream and encoding the variable length encoded date stream according to byte length. A 2 byte length is encoded by 2 bits having the values "00". Encoded lengths of 3 and 4 bytes are represented respectively by 2 bits having the values "01" and "10". Byte lengths of 5 to 7 are represented by 4 bits "1100" to "1110" and so on to thereby enable an efficient procedure for encoding the length of a bit string during compression.

Claims

1. An apparatus comprising:

means for converting an input data character stream into a variable length encoded data stream; and

means for encoding said variable length encoded data stream according to the following table;

space="preserve" listing-type="tabular">______________________________________ 00 = 2 01 = 3 10 = 4 11 00 = 5 11 01 = 6 11 10 = 7 11 11 0000 = 8 11 11 0001 = 9 11 11 0010 = 10 11 11 0011 = 11 11 11 0100 = 12 11 11 0101 = 13 11 11 0110 = 14 11 11 0111 = 15 11 11 1000 = 16 11 11 1001 = 17 11 11 1010 = 18 11 11 1011 = 19 11 11 1100 = 20 11 11 1101 = 21 11 11 1110 = 22 11 11 1111 0000 = 23 11 11 1111 0001 = 24 11 11 1111 0010 = 25 . . . . . . 11 11 1111 1110 = 37 11 11 1111 1111 0000 = 38 11 11 1111 1111 0001 = 39 etc. ______________________________________

2. A method comprising:

converting an input data character stream into a variable length encoded data stream; and

encoding said variable length encoded data stream according to the following table;

space="preserve" listing-type="tabular">______________________________________ 00 = 2 01 = 3 10 = 4 11 00 = 5 11 01 = 6 11 10 = 7 11 11 0000 = 8 11 11 0001 = 9 11 11 0010 = 10 11 11 0011 = 11 11 11 0100 = 12 11 11 0101 = 13 11 11 0110 = 14 11 11 0111 = 15 11 11 1000 = 16 11 11 1001 = 17 11 11 1010 = 18 11 11 1011 = 19 11 11 1100 = 20 11 11 1101 = 21 11 11 1110 = 22 11 11 1111 0000 = 23 11 11 1111 0001 = 24 11 11 1111 0010 = 25 . . . . . . 11 11 1111 1110 = 37 11 11 1111 1111 0000 = 38 11 11 1111 1111 0001 = 39 etc. ______________________________________