Message compression encoder and encoding method for a communication channel

Claim 2

A message compression encoder for use in a communication channel carrying messages constructed of characters from a predetermined character set, said encoder comprising: (a) a memory having a plurality of storage locations storing comma-free code words representing characters of said predetermined set in accordance with predetermined probabilities of occurrence in messages carried by said communication channel; (b) first means coupled with said memory for receiving fixed-length code words representing characters of messages carried by said communication channel and arranging said received fixed-length code words to generate addresses of said storage locations for addressing said memory; (c) said memory being operable in response to addressing of said storage locations to output stored fixed-length comma-free code words which contain variable-length code words therein representing the same characters represented by said fixed-length code words but being composed of fewer bits than compose said fixed length code words; and (d) second means coupled with said memory for receiving said fixed-length comma-free code words from said memory and for separating therefrom and outputting said variable-length code words and thereby transforming said fixed-length code words carried by said communication channel to variable-length code words having fewer bits.

Claim 3

The encoder of claim 1 wherein said memory is a read-only memory.

Claim 4

The encoder of claim 1 wherein said first means is a temporary storage buffer.

Claim 5

The encoder of claim 3 wherein said temporary storage buffer is a serial-in and parallel-out temporary storage buffer.

Claim 6

The encoder of claim 1 wherein said second means includes a parallel-in and serial-out temporary storage buffer.

Claim 7

The encoder of claim 1 wherein said second means includes: a temporary storage buffer for receiving said fixed-length comma-free code words from said memory and outputting said fixed-length comma-free code words; and a detector coupled with said temporary storage buffer for receiving said fixed-length comma-free code words from said temporary storage buffer and detecting the end of said variable-length code words contained therein for separating therefrom and outputting said variable-length code words.

Claim 8

The encoder of claim 1 wherein said memory includes: said storage locations in a first part storing comma-free code words which represent characters having probabilities of occurrence not conditioned on the previous occurrence of a particular character; and said storage locations in a second part storing comma-free code words which represent characters having probabilities of occurrence conditioned on the previous occurrence of a particular character.

Claim 9

The encoder of claim 1 wherein: said first means is operable to reset itself to an initial condition so as to remove previously received fixed-length code words therefrom in response to receipt of a predetermined code word; and said memory is coupled with said first means and stores said predetermined code word at one of said storage locations in said memory, said memory being operable to output said predetermined code word upon said storage location storing said predetermined code word being addressed by said first means.

Claim 10

The encoder of claim 8 wherein said predetermined code word represents a blank character of said predetermined set.

Claim 11

A message compression encoder for use in a communication channel carrying messages constructed of characters from a predetermined character set, said encoder comprising: (a) a read-only memory having a plurality of storage locations storing comma-free code words representing characters of said predetermined set in accordance with predetermined probabilities of occurrence in messages carried by said communication channel; (b) an input temporary storage buffer coupled with said read-only memory for receiving fixed-length code words representing characters of messages carried by said communication channel and arranging said received fixed-length code words to generate addresses of said storage locations for addressing said read-only memory; (c) said read-only memory being operable in response to addressing of said storage locations of said read-only memory to output stored fixed-length comma-free code words which contain variable-length code words therein representing the same characters represented by said fixed-length code words but being composed of fewer bits than compose said fixed-length code words; (d) an output temporary storage buffer coupled with said read-only memory for receiving said fixed-length comma-free code words from said read-only memory and outputting said fixed-length comma-free code words; and (e) a detector coupled with said output temporary storage buffer for receiving said fixed-length comma-free code words therefrom and detecting the end of said variable-length code words contained therein for separating said variable-length code words therefrom and outputting said variable-length code words in concatenated form so as to thereby transform said fixed-length code words carried by said communication channel to variable-length code words having fewer bits and concatenated together.

Claim 12

A message compression encoder for use in a communication channel carrying messages constructed of characters from a predetermined character set, said encoder comprising: (a) a read-only memory having a plurality of storage locations storing comma-free code words representing characters of said predetermined set in accordance with predetermined probabilities of occurrence in messages carried by said communication channel; (b) an input temporary storage buffer coupled with said read-only memory for receiving fixed-length code words representing characters of messages carried by said communication channel and arranging said received fixed-length code words to generate addresses of said storage locations for addressing said read-only memory; (c) said read-only memory being operable in response to addressing of said storage locations of said read-only memory to output stored fixed-length comma-free code words which contain variable-length code words therein representing the same characters represented by said fixed-length code words but being composed of fewer bits than compose said fixed-length code words; (d) an output temporary storage buffer coupled with said read-only memory for receiving said fixed-length comma-free code words from said read-only memory and outputting said fixed-length comma-free code words; and (e) a detector coupled with said output temporary storage buffer for receiving said fixed-length comma-free code words therefrom and detecting the end of said variable-length code words contained therein for separating said variable-length code words therefrom and outputting said variable-length code words in concatenated form so as to thereby transform said fixed-length code words carried by said communication channel to variable-length code words having fewer bits and concatenated together.

Claim 13

The encoder of claim 10 wherein said input temporary storage buffer is a serial-in and parallel-out temporary storage buffer.

Claim 14

The encoder of claim 10 wherein said output temporary storage buffer is a parallel-in and serial-out temporary storage buffer.

Claim 15

The encoder of claim 10 wherein said read-only memory includes: said storage locations in a first part storing comma-free code words which represent characters having probabilities of occurrence not conditioned on the previous occurrence of a particular character; and said storage locations in a second part storing comma-free code words which represent characters having probabilities of occurrence conditioned on the previous occurrence of a particular character.

Claim 16

The encoder of claim 10 wherein: said input temporary storage buffer is operable to reset itself to an initial condition so as to remove previously received fixed-length code words therefrom in response to receipt of a predetermined code word; and said read-only memory is coupled with said input temporary storage buffer and stores said predetermined code word at one of said storage locations of said read-only memory, said read-only memory being operable to output said predetermined code word upon said storage location storing said predetermined code word being addressed by said input temporary storage buffer.

Claim 17

The encoder of claim 14 wherein said predetermined code word represents a blank character of said predetermined set.

Claim 18

A message compression encoding method for use in a communication channel carrying messages constructed of characters from a predetermined character set, said encoding method comprising the steps of: (a) storing fixed-length comma-free code words representing characters of said predetermined set in a plurality of storage locations of a memory in accordance with predetermined probabilities of occurrence in messages carried by said communication channel; (b) receiving in an input temporary storage buffer fixed-length code words representing characters of messages carried by said communication channel and arranging said fixed-length code words therein to generate addresses of said storage locations for addressing said memory; (c) in response to addressing said storage locations of memory, outputting stored fixed-length comma-free code words from said memory which contain variable-length code words representing the same characters as represented by said fixed-length code words but being composed of fewer bits than compose said fixed-length code words; and (d) receiving in an output temporary storage buffer said fixed-length comma-free code words from said storage locations of said memory and separating said variable-length code words therefrom and outputting said variable-length code words in concatenated from so as to thereby transform said fixed-length code words carried by said communication channel to variable-length code words having fewer bits and concatenated together.

Claim 19

A message compression encoding method for use in a communication channel carrying messages constructed of characters from a predetermined character set, said encoding method comprising the steps of: (a) storing fixed-length comma-free code words representing characters of said predetermined set in a plurality of storage locations of a memory in accordance with predetermined probabilities of occurrence in messages carried by said communication channel; (b) receiving in an input temporary storage buffer fixed-length code words representing characters of messages carried by said communication channel and arranging said fixed-length code words therein to generate addresses of said storage locations for addressing said memory; (c) in response to addressing said storage locations of memory, outputting stored fixed-length comma-free code words from said memory which contain variable-length code words representing the same characters as represented by said fixed-length code words but being composed of fewer bits than compose said fixed-length code words; and (d) receiving in an output temporary storage buffer said fixed-length comma-free code words from said storage locations of said memory and separating said variable-length code words therefrom and outputting said variable-length code words in concatenated from so as to thereby transform said fixed-length code words carried by said communication channel to variable-length code words having fewer bits and concatenated together.

Claim 20

The method of claim 16 further comprising: resetting said input temporary storage buffer to an initial condition so as to remove previously received fixed-length code words therefrom in response to receipt of a predetermined code word outputted from one of said storage locations of said memory upon said storage location storing said predetermined code word being addressed by said input temporary storage buffer.

Claim 21

The method of claim 17 wherein said predetermined code word represents a blank character of said predetermined set.

Claim 22

The method of claim 16 wherein said storing includes storing said fixed-length comma-free code words representing characters of said predetermined set in a plurality of storage locations of a read-only memory.

Claim 23

The method of claim 16 wherein said separating of said variable-length code words from said fixed-length comma-free code words includes detecting the end of said variable-length code words contained therein.

Claim 24

The method of claim 16 wherein said storing includes: storing in storage locations in a first part of said memory comma-free code words which represent characters having probabilities of occurrence not conditioned on the previous occurrence of a particular character; and storing in storage locations in a second part of said memory comma-free code words which represent characters having probabilities of occurrence conditioned on the previous occurrence of a particular character.