mleku
6bd773cdf0
Removed redundant length checks and streamlined error handling for XOR operations. Simplified the loop to count differing bits by iterating directly over the XOR result. This improves code readability and reduces duplication.
47 lines
1.2 KiB
Go
47 lines
1.2 KiB
Go
package nilsimsa
|
|
|
|
import (
|
|
"fmt"
|
|
)
|
|
|
|
func Evaluate(a, b []byte) (bitDiffCount int, err error) {
|
|
var c []byte
|
|
if c, err = XOR(a, b); err != nil {
|
|
return
|
|
}
|
|
for _, v := range c {
|
|
bitDiffCount += countBits(v)
|
|
}
|
|
return bitDiffCount, nil
|
|
}
|
|
|
|
// Count the number of `1` bits in a byte
|
|
func countBits(x byte) int {
|
|
count := 0
|
|
for x > 0 {
|
|
count += int(x & 1) // Add the last bit
|
|
x >>= 1 // Right shift the bits
|
|
}
|
|
return count
|
|
}
|
|
|
|
// XOR is a simple bitwise XOR on two nilsimsa hashes. This is used in the simple distance count
|
|
// in Evaluate but could also be used against multiple samples of text from the same author to
|
|
// create a metric of the variety of their text by XORing all of them together.
|
|
func XOR(a, b []byte) (c []byte, err error) {
|
|
// Check if the lengths of the strings are the same
|
|
if len(a) != len(b) {
|
|
return nil, fmt.Errorf("byte strings are of different lengths %d and %d", len(a), len(b))
|
|
}
|
|
if len(a) != 32 || len(b) != 32 {
|
|
return nil, fmt.Errorf("input nilsimsa hashes must be 32 bytes each, got %d and %d",
|
|
len(a), len(b))
|
|
}
|
|
c = make([]byte, 32)
|
|
for i := 0; i < len(a); i++ {
|
|
// XOR the bytes and count the number of `1` bits
|
|
c[i] = a[i] ^ b[i]
|
|
}
|
|
return
|
|
}
|