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---
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license: mit
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tags:
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- pytorch
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- safetensors
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- threshold-logic
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- neuromorphic
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- error-detection
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- crc
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---
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# threshold-crc4
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CRC-4 generator using polynomial x^4 + x + 1 (CRC-4-ITU).
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## Function
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crc4(d3, d2, d1, d0) -> (crc3, crc2, crc1, crc0)
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Computes 4-bit CRC for 4-bit input data.
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## Polynomial
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G(x) = x^4 + x + 1 = 10011 (binary)
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This is the ITU-T standard CRC-4 polynomial.
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## Parallel CRC Equations
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For 4-bit input, the CRC bits are:
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- crc0 = d3 XOR d0
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- crc1 = d2 XOR d1 XOR d0
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- crc2 = d3 XOR d1
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- crc3 = d3 XOR d2
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## Truth Table (selected)
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| Data | CRC |
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|------|-----|
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| 0000 | 0000 |
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| 0001 | 0011 |
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| 1000 | 1101 |
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| 1111 | 0010 |
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## Architecture
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Each CRC bit is computed using XOR gates:
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```
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d3 d2 d1 d0
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│ │ │ │
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├──┼──┼──┼──► XOR ──► crc0 (d3^d0)
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│ │ │ │
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│ ├──┼──┼──► XOR ──► crc3 (d3^d2)
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│ │ │ │
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├──┼──┼──┼──► XOR ──► crc2 (d3^d1)
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│ │ │ │
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│ └──┴──┴──► XOR3 ─► crc1 (d2^d1^d0)
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```
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## Parameters
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|---|---|
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| Inputs | 4 |
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| Outputs | 4 |
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| Neurons | 15 |
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| Layers | 4 |
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| Parameters | 61 |
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| Magnitude | 50 |
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## CRC Properties
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- Detects all single-bit errors
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- Detects all odd numbers of bit errors
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- Detects burst errors up to length 4
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## Usage
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```python
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from safetensors.torch import load_file
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w = load_file('model.safetensors')
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# Append CRC to data for transmission
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# Receiver recomputes CRC; if non-zero, error detected
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```
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## License
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MIT
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