mleku
4f16b0b2fd
Corrected a typo in a comment within `nilsimsa.go`. Introduced a new `Evaluate` function in `evaluate.go` to compute the bitwise difference between two Nilsimsa hash values, ensuring input validation and proper bit counting logic.
36 lines
811 B
Go
36 lines
811 B
Go
package nilsimsa
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import (
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"fmt"
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)
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func Evaluate(a, b []byte) (int, error) {
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// Check if the lengths of the strings are the same
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if len(a) != len(b) {
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return 0, fmt.Errorf("byte strings are of different lengths %d and %d", len(a), len(b))
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}
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if len(a) != 32 || len(b) != 32 {
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return 0, fmt.Errorf("input nilsimsa hashes must be 32 bytes each, got %d and %d",
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len(a), len(b))
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}
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// Count the differing bits
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bitDiffCount := 0
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for i := 0; i < len(a); i++ {
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// XOR the bytes and count the number of `1` bits
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xor := a[i] ^ b[i]
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bitDiffCount += countBits(xor)
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}
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return bitDiffCount, nil
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}
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// Count the number of `1` bits in a byte
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func countBits(x byte) int {
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count := 0
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for x > 0 {
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count += int(x & 1) // Add the last bit
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x >>= 1 // Right shift the bits
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}
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return count
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}
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