Variable-length decoding apparatus
First Claim
1. A variable-length decoding apparatus comprising:
- a barrel shifter for shifting continuous variable-length codes by a predetermined number of bits;
a prefix data generating portion previously containing (i) a plurality of predetermined patterns each having a predetermined code length comprising a plurality of bits and (ii) a plurality of bank addresses in each of which the number of bits is smaller than the code length of any of said predetermined patterns and which are respectively assigned to said predetermined patterns;
said prefix data generating portion being arranged such that each variable-length code supplied from said barrel shifter is compared, from the head part thereof, with said plurality of predetermined patterns and that one of the bank addresses that corresponds to the identical predetermined pattern is supplied;
a look-up table previously containing a large number of decoded data obtained by decoding a large number of variable-length codes; and
said look-up table being arranged such that, using, as an address, (i) said address supplied by said prefix data generating portion and (ii) the remaining part of said variable-length code supplied from said barrel shifter, other than said predetermined pattern, there is supplied the decoded data corresponding to said variable-length code supplied from said barrel shifter.
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Accused Products
Abstract
A prefix data generating portion is arranged such that a bit string having bits in predetermined number supplied from a barrel shifter is compared, from the head part thereof, with predetermined patterns and that there is supplied a less-bit bank address assigned to the identical predetermined pattern. In a look-up table, a decoded data is addressed using (i) an upper address of the bank address and (ii) a lower address of a plurality of remaining bits of the code, other than the predetermined pattern. Accordingly, the look-up table can be addressed with an address in which the number of bits is smaller than that of the code. This reduces the look-up table in capacity, enabling to provide a variable-length decoding apparatus reduced in hardware size.
40 Citations
15 Claims
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1. A variable-length decoding apparatus comprising:
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a barrel shifter for shifting continuous variable-length codes by a predetermined number of bits; a prefix data generating portion previously containing (i) a plurality of predetermined patterns each having a predetermined code length comprising a plurality of bits and (ii) a plurality of bank addresses in each of which the number of bits is smaller than the code length of any of said predetermined patterns and which are respectively assigned to said predetermined patterns; said prefix data generating portion being arranged such that each variable-length code supplied from said barrel shifter is compared, from the head part thereof, with said plurality of predetermined patterns and that one of the bank addresses that corresponds to the identical predetermined pattern is supplied; a look-up table previously containing a large number of decoded data obtained by decoding a large number of variable-length codes; and said look-up table being arranged such that, using, as an address, (i) said address supplied by said prefix data generating portion and (ii) the remaining part of said variable-length code supplied from said barrel shifter, other than said predetermined pattern, there is supplied the decoded data corresponding to said variable-length code supplied from said barrel shifter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 15)
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8. A variable-length decoding apparatus comprising:
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a barrel shifter for shifting continuous variable-length codes by a predetermined number of bits; a plurality of prefix data generating portions respectively disposed for the plurality of groups, except for the last-positioned group, into which each of a plurality of codes is divided; said prefix data generating portions previously containing (i) a plurality of predetermined patterns each having a predetermined code length comprising a plurality of bits and (ii) a plurality of bank addresses in each of which the number of bits is smaller than the code length of any said predetermined patterns and which are respectively assigned to said predetermined patterns; said prefix data generating portions being arranged such that each variable-length code supplied from said barrel shifter is compared, from the head part thereof, with said plurality of predetermined patterns and that one of the bank addresses that corresponds to the identical predetermined patterns are supplied; a look-up table previously containing a large number of decoded data obtained by decoding a large number of variable-length codes; and said look-up table being arranged such that, using as an address, (i) said bank addresses respectively supplied by said prefix data generating portions and (ii) the remaining part of said variable-length code supplied from said barrel shifter, other than said identical predetermined patterns, there is supplied the decoded data corresponding to said variable-length code supplied from said barrel shifter. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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Specification