METHOD AND APPARATUS FOR PRODUCING PROGRAMMABLE PROBABILITY DISTRIBUTION FUNCTION OF PSEUDO-RANDOM NUMBERS

• US 20150095274A1
• Filed: 03/04/2014
• Published: 04/02/2015
• Est. Priority Date: 10/02/2013
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: LAMB, Aaron Douglass
• Granted Patent: US 9,417,845 B2
• Time in Patent Office: Days
• US Class Current: 706/25
• CPC Class Codes: G06F 7/584 using finite field arithmetic, e.g. using a linear feedback shift register
• CPC Class Codes: G06N 3/047 Probabilistic or stochastic networks
• CPC Class Codes: G06N 3/049 Temporal neural networks, e.g. delay elements, oscillating neurons or pulsed inputs
• CPC Class Codes: G06N 3/063 using electronic means

Abstract

Certain aspects of the present disclosure provide methods and apparatus for producing programmable probability distribution function of pseudo-random numbers that can be utilized for filtering (dropping and passing) neuron spikes. The present disclosure provides a simpler, smaller, and lower-power circuit than that typically used. It can be programmed to produce any of a variety of non-uniformly distributed sequences of numbers. These sequences can approximate true probabilistic distributions, but maintain sufficient pseudo-randomness to still be considered random in a probabilistic sense. This circuit can be an integral part of a filter block within an ASIC chip emulating an artificial nervous system.

Claims

1. A method, comprising:

generating a sequence of random numbers;

performing bit-level operations on the generated sequence of random numbers to generate a first sequence of pseudo-random numbers with programmable probability distribution function (PDF);

generating another sequence of random numbers; and

performing bit-level operations between the first sequence and the other sequence to generate a second sequence of pseudo-random numbers with programmable PDF.

2. The method of claim 1, wherein:

the sequence of random numbers is generated using first Linear Feedback Shift Registers (LFSRs), and

the other sequence of random numbers is generated using second LFSRs separate from the first LFSRs.

3. The method of claim 1, wherein:

bits of the sequence of random numbers are ANDed, and

the ANDed bits are passed through a cascade of OR gates to obtain bit-mask values.

4. The method of claim 3, further comprising:

applying the bit-mask values to bits of the sequence of random numbers to generate the first sequence.

5. The method of claim 3, further comprising:

performing AND operation between the bits passed through the cascade of OR gates and a first bit-mask to obtain a range limited sequence of random numbers.

6. The method of claim 5, further comprising:

performing OR operation between bits of the range limited sequence and a second bit-mask to obtain another sequence of random numbers with PDF having whitened low-value portions.

7. The method of claim 1, further comprising:

decoupling the first sequence from the second sequence using a controllable multiplexor.

8. The method of claim 7, further comprising:

performing bit-level operations using an output of the multiplexer, bits of the first sequence and bits of the other sequence to generate the second sequence of pseudo-random numbers with programmable PDF.

9. The method of claim 1, further comprising:

performing OR operation between the second sequence of pseudo-random numbers and a bit-mask to adjust the programmable PDF of the second sequence.

10. The method of claim 1, further comprising:

dropping spikes associated with artificial neurons of an artificial nervous system in accordance with the PDF of the second sequence of pseudo-random numbers.

11. The method of claim 1, wherein:

the sequence of random numbers is generated using a first Gold Code Generator, and

the other sequence of random numbers is generated using a second Gold Code Generator separate from the first Gold Code Generator.

12. An apparatus, comprising:

a first circuit configured to generate a sequence of random numbers;

a second circuit configured to perform bit-level operations on the generated sequence of random numbers to generate a first sequence of pseudo-random numbers with programmable probability distribution function (PDF);

a third circuit configured to generate another sequence of random numbers; and

a fourth circuit configured to perform bit-level operations between the first sequence and the other sequence to generate a second sequence of pseudo-random numbers with programmable PDF.

13. The apparatus of claim 12, wherein:

the first circuit configured to generate the sequence of random numbers comprises first Linear Feedback Shift Registers (LFSRs), and

the third circuit configured to generate the other sequence of random numbers comprises second LFSRs separate from the first LFSRs.

14. The apparatus of claim 12, wherein the second circuit is further configured to:

perform AND operation on bits of the sequence of random numbers, and

pass the ANDed bits through a cascade of OR gates to obtain bit-mask values.

15. The apparatus of claim 14, wherein the second circuit is further configured to:

apply the bit-mask values to bits of the sequence of random numbers to generate the first sequence.

16. The apparatus of claim 14, wherein the second circuit is further configured to:

perform AND operation between the bits passed through the cascade of OR gates and a first bit-mask to obtain a range limited sequence of random numbers.

17. The apparatus of claim 16, wherein the second circuit is further configured to:

perform OR operation between bits of the range limited sequence and a second bit-mask to obtain another sequence of random numbers with PDF having whitened low-value portions.

18. The apparatus of claim 12, further comprising:

a controllable multiplexor configured to decouple the first sequence from the second sequence.

19. The apparatus of claim 18, wherein the fourth circuit is further configured to:

perform bit-level operations using an output of the multiplexer, bits of the first sequence and bits of the other sequence to generate the second sequence of pseudo-random numbers with programmable PDF.

20. The apparatus of claim 12, further comprising:

a fifth circuit configured to perform OR operation between the second sequence of pseudo-random numbers and a bit-mask to adjust the programmable PDF of the second sequence.

21. The apparatus of claim 12, further comprising:

a fifth circuit configured to drop spikes associated with artificial neurons of an artificial nervous system comprising the apparatus in accordance with the PDF of the second sequence of pseudo-random numbers.

22. The apparatus of claim 12, wherein:

the first circuit configured to generate the sequence of random numbers comprises a first Gold Code Generator, and

the third circuit configured to generate the other sequence of random numbers comprises a second Gold Code Generator separate from the first Gold Code Generator.

23. An apparatus, comprising:

means for generating a sequence of random numbers;

means for performing bit-level operations on the generated sequence of random numbers to generate a first sequence of pseudo-random numbers with programmable probability distribution function (PDF);

means for generating another sequence of random numbers; and

means for performing bit-level operations between the first sequence and the other sequence to generate a second sequence of pseudo-random numbers with programmable PDF.

24. The apparatus of claim 23, wherein:

the means for generating the sequence of random numbers comprises means for using first Linear Feedback Shift Registers (LFSRs), and

the means for generating the other sequence of random numbers comprises means for using second LFSRs separate from the first LFSRs.

25. The apparatus of claim 23, further comprising:

means for performing AND operation on bits of the sequence of random numbers, and

means for passing the ANDed bits through a cascade of OR gates to obtain bit-mask values.

26. The apparatus of claim 25, further comprising:

means for applying the bit-mask values to bits of the sequence of random numbers to generate the first sequence.

27. The apparatus of claim 25, further comprising:

means for performing AND operation between the bits passed through the cascade of OR gates and a first bit-mask to obtain a range limited sequence of random numbers.

28. The apparatus of claim 27, further comprising:

means for performing OR operation between bits of the range limited sequence and a second bit-mask to obtain another sequence of random numbers with PDF having whitened low-value portions.

29. The apparatus of claim 23, further comprising:

means for decoupling the first sequence from the second sequence using a controllable multiplexor.

30. The apparatus of claim 29, further comprising:

means for performing bit-level operations using an output of the multiplexer, bits of the first sequence and bits of the other sequence to generate the second sequence of pseudo-random numbers with programmable PDF.

31. The apparatus of claim 23, further comprising:

means for performing OR operation between the second sequence of pseudo-random numbers and a bit-mask to adjust the programmable PDF of the second sequence.

32. The apparatus of claim 23, further comprising:

means for dropping spikes associated with artificial neurons of an artificial nervous system comprising the apparatus in accordance with the PDF of the second sequence of pseudo-random numbers.

33. The apparatus of claim 23, wherein:

the mans for generating the sequence of random numbers comprises means for using a first Gold Code Generator, and

the means for generating the other sequence of random numbers comprises means for using a second Gold Code Generator separate from the first Gold Code Generator.

34. A computer program product, comprising a non-transitory computer-readable medium having instructions executable to:

generate a sequence of random numbers;

perform bit-level operations on the generated sequence of random numbers to generate a first sequence of pseudo-random numbers with programmable probability distribution function (PDF);

generate another sequence of random numbers; and

perform bit-level operations between the first sequence and the other sequence to generate a second sequence of pseudo-random numbers with programmable PDF.

35. The computer program product of claim 34, wherein the computer-readable medium further comprising code for:

generating the sequence of random numbers by using first Linear Feedback Shift Registers (LFSRs), and

generating the other sequence of random numbers by using second LFSRs separate from the first LFSRs.

36. The computer program product of claim 34, wherein the computer-readable medium further comprising code for:

performing AND operation on bits of the sequence of random numbers, and

passing the ANDed bits through a cascade of OR gates to obtain bit-mask values.

37. The computer program product of claim 36, wherein the computer-readable medium further comprising code for:

applying the bit-mask values to bits of the sequence of random numbers to generate the first sequence.

38. The computer program product of claim 36, wherein the computer-readable medium further comprising code for:

performing AND operation between the bits passed through the cascade of OR gates and a first bit-mask to obtain a range limited sequence of random numbers.

39. The computer program product of claim 38, wherein the computer-readable medium further comprising code for:

performing OR operation between bits of the range limited sequence and a second bit-mask to obtain another sequence of random numbers with PDF having whitened low-value portions.

40. The computer program product of claim 34, wherein the computer-readable medium further comprising code for:

decoupling the first sequence from the second sequence using a controllable multiplexor.

41. The computer program product of claim 40, wherein the computer-readable medium further comprising code for:

performing bit-level operations using an output of the multiplexer, bits of the first sequence and bits of the other sequence to generate the second sequence of pseudo-random numbers with programmable PDF.

42. The computer program product of claim 34, wherein the computer-readable medium further comprising code for:

performing OR operation between the second sequence of pseudo-random numbers and a bit-mask to adjust the programmable PDF of the second sequence.

43. The computer program product of claim 34, wherein the computer-readable medium further comprising code for:

dropping spikes associated with artificial neurons of an artificial nervous system in accordance with the PDF of the second sequence of pseudo-random numbers.

44. The computer program product of claim 34, wherein the computer-readable medium further comprising code for:

generating the sequence of random numbers by using a first Gold Code Generator, and

generating the other sequence of random numbers by using a second Gold Code Generator separate from the first Gold Code Generator.