| 摘要 |
A ROM includes a single dictionary of variable length codewords wherein Huffman codewords are assigned all members of the dictionary set, including one key codeword being assigned as a prefix codeword segment for a relatively large subgroup of the set, based on the combined probability of occurrence of the subgroup as compared to the individual probabilities of occurrences of the remaining members of the dictionary set. The key codeword is an indication of a departure from straightforward Huffman coding, to prepare an alternative coding scheme for developing a longer codeword which uses the key codeword as a prefix portion of that longer codeword. A unique suffix codeword segment follows the key codeword prefix for particularly identifying each member of the subgroup. The combined probability of occurrence of a member of the subgroup is higher than the probability of occurrence of codewords of shorter length, but the individual probabilities are significantly lower. The subgroup members can be assigned codeword lengths significantly shorter than codewords that would be assigned in straightforward Huffman coding. |
