Electronic multimode data shift device, in particular for coding/decoding with an LDPC code
An electronic device includes N inputs to receive R input data, R being able to take values from 1 to N, and N outputs. A configurable shift circuit is coupled between the N inputs and N outputs and has a cascade of shift stages, each shift stage comprising at least N controllable multiplexers. Each multiplexer includes first and second elementary inputs respectively coupled to a first input and a second input taken from among the N inputs so as to, on command, not shift a data item present on the first elementary input and shift a data item present on the second elementary input by an elementary shift value dependent on a rank of the shift stage, a direction of the shift being identical for each multiplexer. Control circuitry controls the multiplexers to deliver the R input data on R outputs.
1. An electronic device comprising:
N inputs configured to receive R input data, R being able to take values from 1 to N;
N outputs; and
a configurable shift circuit coupled between the N inputs and N outputs and comprising
a cascade of shift stages,
each shift stage comprising at least N controllable multiplexers,
each multiplexer including first and second elementary inputs respectively coupled to a first input and a second input taken from among the N inputs so as to, on command, not shift a data item present on the first elementary input and shift a data item present on the second elementary input by an elementary shift value dependent on a rank of the shift stage, a direction of the shift being identical for each multiplexer, and
control circuitry configured to control the multiplexers to deliver the R input data on R outputs.
2. An electronic device according to claim 1 , wherein the number of shift stages is equal to ceil(log 2 (N)) and ceil(X) denotes a smallest integer greater than X.
3. An electronic device according to claim 1 , wherein each shift stage comprises a number of multiplexers equal to N+(2 i *floor((N−2 i-1 −1)/2 i ))) and floor(X) denotes a highest integer less than or equal to X; and wherein i denotes the rank of the shift stage, a first shift stage having rank i equal to 1.
4. An electronic device according claim 1 , wherein one of the N inputs is coupled directly to two multiplexers and each other N input of successive ranks is coupled directly to at least three different multiplexers so that a data item present on one other input can be shifted in a direction of the shift by an overall shift value less than N and compatible with a rank of the N input.
5. An electronic device according to claim 4 , wherein the other inputs are of rank 2 to N and each of these inputs is coupled directly to at least three multiplexers so that a data item present on one of these inputs can be shifted in the direction of the shift by an overall shift value lying between N−1 and N−r+1; and wherein r denotes a rank of an input.
6. An electronic device according to claim 1 , wherein the elementary shift value of a stage of rank i is identical for the multiplexers of the stage of rank i and is equal to 2 i-1 , a first stage being a stage of rank i equal to 1, and the second elementary inputs of all multiplexers of a stage are respectively coupled to inputs of consecutive ranks.
7. An electronic device according claim 1 , wherein a last stage comprises N multiplexers.
8. An electronic device according to claim 7 , wherein the first elementary inputs of N multiplexers of ranks 1 to N of a stage of rank i are respectively coupled to the N inputs of ranks 1 to N; and wherein the second elementary input of a multiplexer of rank 1 of a stage of rank i equal to 1 is coupled to an input of rank N; and wherein the first and second elementary inputs of other multiplexers of the stage of rank i are coupled to at least one input of rank N to 2 with respect to an elementary shift value associated with this stage; and wherein second elementary inputs of at least one of the N multiplexers of the last stage are also coupled to inputs of rank N to 2 having regard to the elementary shift value associated with this stage.
9. An electronic device according claim 1 , wherein each shift stage comprises a first group of adjacent multiplexers and a second group of adjacent multiplexers, a number of multiplexers in each group based upon a rank of the stage and a value S+N−R where S denotes a desired overall shift value and R denotes a rank of an input; and wherein the control circuitry is configured to control in an independent manner the first and second groups of adjacent multiplexers of each stage, and in a same manner multiplexers of a group of a stage, so that multiplexers of first groups of adjacent multiplexers of each shift stage effect a shift equal to S and that multiplexers of all second groups of adjacent multiplexers of each shift stage effect a shift equal to S+N−R.
10. An electronic device according to claim 9 , wherein a number of multiplexers of the first group of adjacent multiplexers of a stage of rank i is equal to min (MX, N−(mod(S+N−,2 i )−(N−R))), mod(S+N−R,2 i ) representing a remainder after dividing S+N−R by 2 i , min representing a “minimum” function, and MX representing a number of multiplexing means of the stage of rank i.
11. An electronic device according to claim 1 , wherein the configurable shift circuit is incorporated in an integrated circuit.
12. An electronic device according to claim 1 , wherein the configurable shift circuit defines a channel coding device able to perform an encoding with a low-density parity-check (LDPC) code.
13. An electronic device according to claim 1 , wherein the configurable shift circuit defines a channel decoding device able to perform a decoding of blocks encoded with an LDPC code.
14. An electronic device comprising:
N inputs to receive R input data, R being able to take values from 1 to N;
N outputs; and
a configurable shift circuit coupled between the N inputs and N outputs and comprising
a cascade of shift stages, the number of shift stages being equal to ceil(log 2 (N)) where ceil(X) denotes a smallest integer greater than X,
each shift stage comprising N+(2 i *floor((N−2 i-1 −1)/2 i ))) controllable multiplexers where floor(X) denotes a highest integer less than or equal to X and i denotes the rank of the shift stage, a first shift stage having rank i equal to 1,
each multiplexer including first and second elementary inputs respectively coupled to a first input and a second input taken from among the N inputs so as to, on command, not shift a data item present on the first elementary input and shift a data item present on the second elementary input by an elementary shift value dependent on a rank of the shift stage, a direction of the shift being identical for each multiplexer, and
control circuitry configured to control the multiplexers to deliver the R input data on R outputs.
15. An electronic device according claim 14 , wherein one of the N inputs is coupled directly to two multiplexers and each other N input of successive ranks is coupled directly to at least three different multiplexers so that a data item present on one other input can be shifted in a direction of the shift by an overall shift value less than N and compatible with a rank of the N input.
16. An electronic device according to claim 15 , wherein the other inputs are of rank 2 to N and each of these inputs is coupled directly to at least three multiplexers so that a data item present on one of these inputs can be shifted in the direction of the shift by an overall shift value lying between N−1 and N−r+1; and wherein r denotes a rank of an input.
17. An electronic device according to claim 14 , wherein the elementary shift value of a stage of rank i is identical for the multiplexers of the stage of rank i and is equal to 2 i-1 , a first stage being a stage of rank i equal to 1, and the second elementary inputs of all multiplexers of a stage are respectively coupled to inputs of consecutive ranks.
18. An electronic device according claim 14 , wherein a last stage comprises N multiplexers.
19. An electronic device according to claim 18 , wherein the first elementary inputs of N multiplexers of ranks 1 to N of a stage of rank i are respectively coupled to the N inputs of ranks 1 to N; and wherein the second elementary input of a multiplexer of rank 1 of a stage of rank i equal to 1 is coupled to an input of rank N; and wherein the first and second elementary inputs of other multiplexers of the stage of rank i are coupled to at least one input of rank N to 2 with respect to an elementary shift value associated with this stage; and wherein second elementary inputs of at least one of the N multiplexers of the last stage are also coupled to inputs of rank N to 2 having regard to the elementary shift value associated with this stage.
20. An electronic device according claim 14 , wherein each shift stage comprises a first group of adjacent multiplexers and a second group of adjacent multiplexers, a number of multiplexers in each group based upon a rank of the stage and a value S+N−R where S denotes a desired overall shift value and R denotes a rank of an input; and wherein the control circuitry is able to control in an independent manner the first and second groups of adjacent multiplexers of each stage, and in a same manner multiplexers of a group of a stage, so that multiplexers of first groups of adjacent multiplexers of each shift stage effect a shift equal to S and that multiplexers of all second groups of adjacent multiplexers of each shift stage effect a shift equal to S+N−R.
21. An electronic device according to claim 14 , wherein the configurable shift circuit is incorporated in an integrated circuit.
22. A method of operating a configurable shift circuit coupled between N inputs able to receive R input data with R being a value from 1 to N, and N outputs, the configurable shift circuit comprising a cascade of shift stages, each comprising at least N controllable multiplexers each having first and second elementary inputs respectively coupled to first and second inputs taken from among the N inputs, the method comprising:
controlling the multiplexers to not shift a data item present on the first elementary input and to shift a data item present on the second elementary input by an elementary shift value dependent on a rank of the shift stage, a direction of the shift being identical for each multiplexer; and
controlling the multiplexers to deliver the R input data on R outputs.
23. A method according claim 22 , further comprising coupling one of the N inputs directly to two multiplexers and coupling each other N input of successive ranks directly to at least three different multiplexers so that a data item present on one other input can be shifted in a direction of the shift by an overall shift value less than N and compatible with a rank of the N input.
24. A method according to claim 23 , wherein the other inputs are of rank 2 to N; and further comprising coupling each of the other inputs directly to at least three multiplexers so that a data item present on one of the other inputs can be shifted in the direction of the shift by an overall shift value lying between N−1 and N−r+1, r denoting a rank of an input.
25. A method according to claim 22 , further comprising coupling the first elementary inputs of N multiplexers of ranks 1 to N of a stage of rank i respectively to the N inputs of ranks 1 to N, coupling the second elementary input of a multiplexer of rank 1 of a stage of rank i equal to 1 to an input of rank N, coupling the first and second elementary inputs of other multiplexers of the stage of rank i to at least one input of rank N to 2 with respect to an elementary shift value associated with this stage, and coupling second elementary inputs of at least one of the N multiplexers of a last stage comprising N multiplexers are to inputs of rank N to 2 having regard to the elementary shift value associated with this stage.