threshold-sec-ded

SEC-DED (8,4) decoder: Single Error Correct, Double Error Detect. Extends Hamming(7,4) with overall parity for double-error detection.

Circuit

codeword[7:0] ──► SEC-DED ──┬──► data[3:0]     (corrected)
                           ├──► error         (error detected)
                           └──► uncorrectable (double error)

Codeword Format

Position: 7  6  5  4  3  2  1  0
Bit:      d3 d2 d1 p3 d0 p2 p1 p0

p0 = overall parity (all bits)
p1 = parity of positions 1,3,5,7
p2 = parity of positions 2,3,6,7
p3 = parity of positions 4,5,6,7
d0-d3 = data bits

Error Handling

Syndrome	Overall Parity	Status
0	0	No error
≠0	1	Single error (correctable)
≠0	0	Double error (detected only)
0	1	Single error in p0 (correctable)

Architecture

Component	Function	Neurons
Syndrome calc (s1,s2,s3)	XOR trees	~63
Overall parity	XOR tree	~21
Error logic	AND/OR	~7
Data correction	Conditional XOR	~12

Total: 95 neurons, 300 parameters, 4 layers

Capabilities

• Correct: Any single-bit error
• Detect: Any double-bit error
• Miss: Triple+ errors may be miscorrected

Test Coverage

• 16 no-error cases: All pass
• 128 single-error cases: All corrected
• 448 double-error cases: All detected

Usage

from safetensors.torch import load_file

w = load_file('model.safetensors')

# Example: data=5 (0101)
# Encoded: 01010110 (with parity bits)
# Flip bit 3: 01011110
# Decoder: corrects to data=5, error=1, uncorrectable=0

Applications

• ECC RAM (Error-Correcting Code memory)
• Data storage systems
• Communication channels
• Safety-critical systems

Files

threshold-sec-ded/
├── model.safetensors
├── create_safetensors.py
├── config.json
└── README.md

License

MIT