C function for matching numeric vectors and calculating error / difference. This was used to detect difference between FFT results
You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
 
 
 
fuzzy-vector-match/src/vec_match.c

346 lines
6.8 KiB

#include <stdint.h>
#include <stdbool.h>
#include <stdlib.h>
#include <stdio.h>
#include <float.h>
#include <math.h>
#include "vec_match.h"
#define SQ(a) ((a)*(a))
#define IS_FZERO(f) ((f) < 0.0f)
#define F2ZERO(f) roundf(-(f))
#define ZERO2F(z) (0.0f - z)
bool vec_match(const float *data, const float *ref,
const vec_match_cfg_t *cfg,
float *fuzzy_match_error, float *abs_match_error)
{
int a, b;
int err_cnt = 0;
float env_err = 0;
float abs_err = 0;
for (uint32_t i = 0; i < cfg->length; i++) {
float peak = FLT_MIN;
float base = FLT_MAX;
// bounds for base and peak search
if (i < cfg->drift_x) {
a = 0;
} else {
a = i - cfg->drift_x;
}
if (i + cfg->drift_x >= cfg->length) {
b = cfg->length - 1;
} else {
b = i + cfg->drift_x;
}
// find base and peak
for (int j = a; j <= b; j++) {
if (peak < ref[j]) peak = ref[j];
if (base > ref[j]) base = ref[j];
}
// apply drift_y
peak += cfg->offset_y; // add abs threshold on top
base -= cfg->offset_y;
// ignore abs threshold difference (float precision error)
if (fabs(ref[i] - data[i]) > cfg->abs_threshold) {
abs_err += SQ(ref[i] - data[i]);
}
if (data[i] >= (base - cfg->abs_threshold) && data[i] <= (peak + cfg->abs_threshold)) {
// within limits
continue;
} else {
//printf("data[%d] out of range: %f, [%f ; %f]\n", i, data[i], base, peak);
if (data[i] < base) env_err += SQ(base - data[i]);
if (data[i] > peak) env_err += SQ(data[i] - peak);
err_cnt++;
}
}
// write error values to provided fields
if (fuzzy_match_error != NULL) *fuzzy_match_error = env_err;
if (abs_match_error != NULL) *abs_match_error = abs_err;
return err_cnt == 0;
}
bool vec_match_packed(const float *data, const float *ref_packed, uint32_t ref_p_len,
const vec_match_cfg_t *cfg,
float *fuzzy_match_error, float *abs_match_error)
{
uint32_t a, b;
float f; // tmp float
pack_walker_t w; // walker
pw_init(&w, ref_packed, ref_p_len);
int err_cnt = 0;
float env_err = 0;
float abs_err = 0;
float ref_at;
for (uint32_t i = 0; i < cfg->length; i++) {
float peak = FLT_MIN;
float base = FLT_MAX;
// bounds for base and peak search
if (i < cfg->drift_x) {
a = 0;
} else {
a = i - cfg->drift_x;
}
if (i + cfg->drift_x >= cfg->length) {
b = cfg->length - 1;
} else {
b = i + cfg->drift_x;
}
// find base and peak
for (uint32_t j = a; j <= b; j++) {
f = pw_get(&w, j);
if (peak < f) peak = f;
if (base > f) base = f;
}
ref_at = pw_get(&w, i);
// apply drift_y
peak += cfg->offset_y; // add abs threshold on top
base -= cfg->offset_y;
// ignore abs threshold difference (float precision error)
if (fabs(ref_at - data[i]) > cfg->abs_threshold) {
abs_err += SQ(ref_at - data[i]);
}
if (data[i] >= (base - cfg->abs_threshold) && data[i] <= (peak + cfg->abs_threshold)) {
// within limits
continue;
} else {
//printf("data[%d] out of range: %f, [%f ; %f]\n", i, data[i], base, peak);
if (data[i] < base) env_err += SQ(base - data[i]);
if (data[i] > peak) env_err += SQ(data[i] - peak);
err_cnt++;
}
}
// write error values to provided fields
if (fuzzy_match_error != NULL) *fuzzy_match_error = env_err;
if (abs_match_error != NULL) *abs_match_error = abs_err;
return err_cnt == 0;
}
// ---- PACKING UTILS ----
uint32_t vec_pack(float *result, uint32_t result_capacity,
const float *data, uint32_t data_length, float threshold)
{
uint32_t result_len = 0;
uint32_t zeroes = 0;
for (uint32_t i = 0; i < data_length; i++) {
if (data[i] < threshold) {
zeroes++;
} else {
// not a zero
// write zero marker to result
if (zeroes) {
if (result_len < result_capacity) {
result[result_len] = ZERO2F(zeroes); // float and negative
}
zeroes = 0;
result_len++; //length is increased even if buffer full
}
if (result_len < result_capacity) {
result[result_len] = data[i];
}
result_len++;
}
}
// handle trailing zeroes
if (zeroes) {
if (result_len < result_capacity) {
result[result_len] = 0.0f - zeroes;
}
result_len++;
}
return result_len;
}
uint32_t vec_pack_auto(float *result, uint32_t result_capacity,
const float *data, uint32_t data_length, float *threshold_p)
{
float thr = 0;
uint32_t ref_pack_len;
// TODO use smarter algorithm
while(true) {
ref_pack_len = vec_pack(result, result_capacity, data, data_length, thr);
printf("try %f -> %d\n", thr, ref_pack_len);//FIXME remove
if (ref_pack_len <= result_capacity) {
if (threshold_p != NULL) *threshold_p = thr;
return result_capacity;
}
thr += 0.1f;
}
}
uint32_t vec_unpack(float *result, uint32_t result_capacity,
const float *compr_data, uint32_t compr_length)
{
uint32_t idx = 0;
for (uint32_t i = 0; i < compr_length; i++) {
if (IS_FZERO(compr_data[i])) {
uint32_t zeroes = F2ZERO(compr_data[i]);
for (uint32_t j = 0; j < zeroes; j++) {
if (idx < result_capacity) {
result[idx] = 0;
}
idx++;
}
} else {
if (idx < result_capacity) {
result[idx] = compr_data[i];
}
idx++;
}
}
return idx;
}
// ---- PACK WALKER CODE ----
// init the pack walker struct
void pw_init(pack_walker_t *wlkr, const float *packed_vec, uint32_t packed_len)
{
wlkr->p_vec = packed_vec;
wlkr->p_length = packed_len;
wlkr->real_idx = 0;
wlkr->p_idx = 0;
wlkr->p_zero_j = 0;
wlkr->p_zero_n = 0;
}
// rewind the struct to first entry, handle leading zero(s)
void pw_rewind(pack_walker_t *w)
{
w->real_idx = 0;
w->p_idx = 0;
if (IS_FZERO(w->p_vec[0])) {
// multi-zero
w->p_zero_n = F2ZERO(w->p_vec[0]);
w->p_zero_j = 1;
} else {
w->p_zero_j = 0;
w->p_zero_n = 0;
}
}
// get value at index in packed vector
float pw_get(pack_walker_t *w, uint32_t idx)
{
if (idx < w->real_idx && idx > w->real_idx / 2) {
// backtrack
while (w->real_idx > idx) {
if (w->p_zero_n && w->p_zero_j > 1) { // multi-zero value
w->p_zero_j--;
} else {
// go to previous
w->p_idx--;
if (IS_FZERO(w->p_vec[w->p_idx])) {
// multi-zero
w->p_zero_n = F2ZERO(w->p_vec[w->p_idx]);
w->p_zero_j = w->p_zero_n;
} else {
w->p_zero_n = 0; // no zeros
}
}
w->real_idx--;
}
} else {
// forward
if (idx < w->real_idx || idx == 0) {
pw_rewind(w);
}
// add until reached
while (w->real_idx < idx && w->p_idx < w->p_length) {
if (w->p_zero_n && w->p_zero_j < w->p_zero_n) { // multi-zero value
w->p_zero_j++;
} else {
// go to next
w->p_idx++;
if (IS_FZERO(w->p_vec[w->p_idx])) {
// multi-zero
w->p_zero_n = F2ZERO(w->p_vec[w->p_idx]);
w->p_zero_j = 1;
} else {
w->p_zero_n = 0; // no zeros
}
}
w->real_idx++;
}
}
// handle overflow. underflow impossible <- index is unsigned
if (w->p_idx >= w->p_length) {
w->p_idx = w->p_length - 1;
return 0;
}
return w->p_zero_n ? 0 : w->p_vec[w->p_idx];
}