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kunlun/import/wq_vtb/inc/metric.h
2024-09-28 14:24:04 +08:00

22 lines
712 B
C

#ifndef METRIC_H
#define METRIC_H
#include "convolutional.h"
// measure the hamming distance of two bit strings
// implemented as population count of x XOR y
static inline distance_t metric_distance(uint16_t x, uint16_t y) {
return count_num(x ^ y);
}
static inline distance_t metric_soft_distance_linear(uint16_t hard_x, const uint8_t *soft_y, size_t len) {
distance_t dist = 0;
for (uint16_t i = 0; i < len; i++) {
uint16_t soft_x = ((int8_t)(0) - (hard_x & 1)) & 0xff;
hard_x >>= 1;
int d = soft_y[i] - soft_x;
dist += (d < 0) ? -d : d;
}
return dist;
}
distance_t metric_soft_distance_quadratic(uint16_t hard_x, const uint8_t *soft_y, size_t len);
#endif