Abstract Electronically decoding variable length minimal redundancy binary input codes into characters in a character set. Code flexibility is provided by easily supporting (1) different transmitted codes for the same outputted character set, and (2) the same transmitted code for different output character sets. Tree structured codes are used for translating minimal redundancy codes into characters, which are well-known in the prior art of Huffman codes, in which the sink vertices in a binary tree correspond to characters in a character set. The set of path vectors in the binary tree is the minimal redundancy encoding for the characters represented by the sinks. A bit sequence store T has its bit positions set to represent the binary tree, in which the bit positions are set to correspond to the vertices in the tree when it is scanned in left list order; and a 1 setting represents an inner vertex and a 0 setting represents a sink vertex in the binary tree. Store T is easily reset to permit easy changes in the binary tree represented therein, in order to support (1) and (2) above. The path vectors in the tree are transmitted as the coded characters are decoded using the correct tree set into store T.
Means for decoding self-defining coded signals received from a transmission device, said signals being coded according to path vectors in a binary tree which represents a character set used for data being transmitted, comprising a bit sequence store having bit positions initially set to 0 and 1 electronically detectible states in accordance with a left list scan of vertices in said binary tree, each bit position setting a zero or one representing the sink or inner state respectively of each vertex encountered in said left list scan, and means for scanning said bit sequence store from a bit position that begins said left list scan to detect a bit position with a sink state determined by inputted path vector coded signals, means for counting the bit positions in said bit sequence store having sink states from the beginning of each scan to generate a sink index count, and outputting the sink index count upon the detection of said bit position by said scanning means as the detected output of said path vector coded signals, whereby said codes are easily changeable by changing the binary tree left list scan settings in said bit sequence store.
Claim 2
Dependent Claim
194 words
Means for decoding self-defining coded signals received from a transmission device, said signals being coded according to path vectors in a binary tree which represents a character set used for data being transmitted, comprising a bit sequence store having bit positions initially set to 0 and 1 electronically detectible states in accordance with a left list scan of vertices in said binary tree, each bit position setting a zero or one representing the sink or inner state respectively of each vertex encountered in said left list scan, and means for scanning said bit sequence store from a bit position that begins said left list scan to detect a bit position with a sink state determined by inputted path vector coded signals, means for counting the bit positions in said bit sequence store having sink states from the beginning of each scan to generate a sink index count, and outputting the sink index count upon the detection of said bit position by said scanning means as the detected output of said path vector coded signals, whereby said codes are easily changeable by changing the binary tree left list scan settings in said bit sequence store.
Claim 3
Dependent Claim
40 words
Means as defined in claim 1 comprising matrix means for decoding the detected output provided by said outputing means into a signal on a unique output line, whereby said output line can be an input for driving an electrical printer.