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