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spo2_algorithm.cpp@0:78a2573ad768, 2019-08-06 (annotated)

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zinnetyazicii53
Date:
Tue Aug 06 12:19:46 2019 +0000
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0:78a2573ad768
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zinnetyazicii53 0:78a2573ad768 1 #include "spo2_algorithm.h"
zinnetyazicii53 0:78a2573ad768 2
zinnetyazicii53 0:78a2573ad768 3
zinnetyazicii53 0:78a2573ad768 4
zinnetyazicii53 0:78a2573ad768 5 const uint16_t auw_hamm[31]={41,276,512,276,41 }; //Hamm= long16(512* hamming(5)');
zinnetyazicii53 0:78a2573ad768 6 //SPO2table is computed as -45.060*ratioAverage* ratioAverage + 30.354 *ratioAverage + 94.845 ;
zinnetyazicii53 0:78a2573ad768 7 const uint8_t uch_spo2_table[184]={ 95, 95, 95, 96, 96, 96, 97, 97, 97, 97, 97, 98, 98, 98, 98, 98, 99, 99, 99, 99,
zinnetyazicii53 0:78a2573ad768 8 99, 99, 99, 99, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100,
zinnetyazicii53 0:78a2573ad768 9 100, 100, 100, 100, 99, 99, 99, 99, 99, 99, 99, 99, 98, 98, 98, 98, 98, 98, 97, 97,
zinnetyazicii53 0:78a2573ad768 10 97, 97, 96, 96, 96, 96, 95, 95, 95, 94, 94, 94, 93, 93, 93, 92, 92, 92, 91, 91,
zinnetyazicii53 0:78a2573ad768 11 90, 90, 89, 89, 89, 88, 88, 87, 87, 86, 86, 85, 85, 84, 84, 83, 82, 82, 81, 81,
zinnetyazicii53 0:78a2573ad768 12 80, 80, 79, 78, 78, 77, 76, 76, 75, 74, 74, 73, 72, 72, 71, 70, 69, 69, 68, 67,
zinnetyazicii53 0:78a2573ad768 13 66, 66, 65, 64, 63, 62, 62, 61, 60, 59, 58, 57, 56, 56, 55, 54, 53, 52, 51, 50,
zinnetyazicii53 0:78a2573ad768 14 49, 48, 47, 46, 45, 44, 43, 42, 41, 40, 39, 38, 37, 36, 35, 34, 33, 31, 30, 29,
zinnetyazicii53 0:78a2573ad768 15 28, 27, 26, 25, 23, 22, 21, 20, 19, 17, 16, 15, 14, 12, 11, 10, 9, 7, 6, 5,
zinnetyazicii53 0:78a2573ad768 16 3, 2, 1 } ;
zinnetyazicii53 0:78a2573ad768 17 static int32_t an_dx[ BUFFER_SIZE-MA4_SIZE]; // delta
zinnetyazicii53 0:78a2573ad768 18 static int32_t an_x[ BUFFER_SIZE]; //ir
zinnetyazicii53 0:78a2573ad768 19 static int32_t an_y[ BUFFER_SIZE]; //red
zinnetyazicii53 0:78a2573ad768 20
zinnetyazicii53 0:78a2573ad768 21 void spo2_algorithm::maxim_heart_rate_and_oxygen_saturation(uint32_t *pun_ir_buffer, int32_t n_ir_buffer_length, uint32_t *pun_red_buffer, int32_t *pn_spo2, int8_t *pch_spo2_valid,
zinnetyazicii53 0:78a2573ad768 22 int32_t *pn_heart_rate, int8_t *pch_hr_valid)
zinnetyazicii53 0:78a2573ad768 23 /**
zinnetyazicii53 0:78a2573ad768 24 * \brief Calculate the heart rate and SpO2 level
zinnetyazicii53 0:78a2573ad768 25 * \par Details
zinnetyazicii53 0:78a2573ad768 26 * By detecting peaks of PPG cycle and corresponding AC/DC of red/infra-red signal, the ratio for the SPO2 is computed.
zinnetyazicii53 0:78a2573ad768 27 * Since this algorithm is aiming for Arm M0/M3. formaula for SPO2 did not achieve the accuracy due to register overflow.
zinnetyazicii53 0:78a2573ad768 28 * Thus, accurate SPO2 is precalculated and save longo uch_spo2_table[] per each ratio.
zinnetyazicii53 0:78a2573ad768 29 *
zinnetyazicii53 0:78a2573ad768 30 * \param[in] *pun_ir_buffer - IR sensor data buffer
zinnetyazicii53 0:78a2573ad768 31 * \param[in] n_ir_buffer_length - IR sensor data buffer length
zinnetyazicii53 0:78a2573ad768 32 * \param[in] *pun_red_buffer - Red sensor data buffer
zinnetyazicii53 0:78a2573ad768 33 * \param[out] *pn_spo2 - Calculated SpO2 value
zinnetyazicii53 0:78a2573ad768 34 * \param[out] *pch_spo2_valid - 1 if the calculated SpO2 value is valid
zinnetyazicii53 0:78a2573ad768 35 * \param[out] *pn_heart_rate - Calculated heart rate value
zinnetyazicii53 0:78a2573ad768 36 * \param[out] *pch_hr_valid - 1 if the calculated heart rate value is valid
zinnetyazicii53 0:78a2573ad768 37 *
zinnetyazicii53 0:78a2573ad768 38 * \retval None
zinnetyazicii53 0:78a2573ad768 39 */
zinnetyazicii53 0:78a2573ad768 40 {
zinnetyazicii53 0:78a2573ad768 41 uint32_t un_ir_mean ,un_only_once ;
zinnetyazicii53 0:78a2573ad768 42 int32_t k ,n_i_ratio_count;
zinnetyazicii53 0:78a2573ad768 43 int32_t i,s ,m, n_exact_ir_valley_locs_count ,n_middle_idx;
zinnetyazicii53 0:78a2573ad768 44 int32_t n_th1, n_npks,n_c_min;
zinnetyazicii53 0:78a2573ad768 45 int32_t an_ir_valley_locs[15] ;
zinnetyazicii53 0:78a2573ad768 46 int32_t an_exact_ir_valley_locs[15] ;
zinnetyazicii53 0:78a2573ad768 47 int32_t an_dx_peak_locs[15] ;
zinnetyazicii53 0:78a2573ad768 48 int32_t n_peak_interval_sum;
zinnetyazicii53 0:78a2573ad768 49
zinnetyazicii53 0:78a2573ad768 50 int32_t n_y_ac, n_x_ac;
zinnetyazicii53 0:78a2573ad768 51 int32_t n_spo2_calc;
zinnetyazicii53 0:78a2573ad768 52 int32_t n_y_dc_max, n_x_dc_max;
zinnetyazicii53 0:78a2573ad768 53 int32_t n_y_dc_max_idx, n_x_dc_max_idx;
zinnetyazicii53 0:78a2573ad768 54 int32_t an_ratio[5],n_ratio_average;
zinnetyazicii53 0:78a2573ad768 55 int32_t n_nume, n_denom ;
zinnetyazicii53 0:78a2573ad768 56 // remove DC of ir signal
zinnetyazicii53 0:78a2573ad768 57 un_ir_mean =0;
zinnetyazicii53 0:78a2573ad768 58 for (k=0 ; k<n_ir_buffer_length ; k++ ) un_ir_mean += pun_ir_buffer[k] ;
zinnetyazicii53 0:78a2573ad768 59 un_ir_mean =un_ir_mean/n_ir_buffer_length ;
zinnetyazicii53 0:78a2573ad768 60 for (k=0 ; k<n_ir_buffer_length ; k++ ) an_x[k] = pun_ir_buffer[k] - un_ir_mean ;
zinnetyazicii53 0:78a2573ad768 61
zinnetyazicii53 0:78a2573ad768 62 // 4 pt Moving Average
zinnetyazicii53 0:78a2573ad768 63 for(k=0; k< BUFFER_SIZE-MA4_SIZE; k++){
zinnetyazicii53 0:78a2573ad768 64 n_denom= ( an_x[k]+an_x[k+1]+ an_x[k+2]+ an_x[k+3]);
zinnetyazicii53 0:78a2573ad768 65 an_x[k]= n_denom/(int32_t)4;
zinnetyazicii53 0:78a2573ad768 66 }
zinnetyazicii53 0:78a2573ad768 67
zinnetyazicii53 0:78a2573ad768 68 // get difference of smoothed IR signal
zinnetyazicii53 0:78a2573ad768 69
zinnetyazicii53 0:78a2573ad768 70 for( k=0; k<BUFFER_SIZE-MA4_SIZE-1; k++)
zinnetyazicii53 0:78a2573ad768 71 an_dx[k]= (an_x[k+1]- an_x[k]);
zinnetyazicii53 0:78a2573ad768 72
zinnetyazicii53 0:78a2573ad768 73 // 2-pt Moving Average to an_dx
zinnetyazicii53 0:78a2573ad768 74 for(k=0; k< BUFFER_SIZE-MA4_SIZE-2; k++){
zinnetyazicii53 0:78a2573ad768 75 an_dx[k] = ( an_dx[k]+an_dx[k+1])/2 ;
zinnetyazicii53 0:78a2573ad768 76 }
zinnetyazicii53 0:78a2573ad768 77
zinnetyazicii53 0:78a2573ad768 78 // hamming window
zinnetyazicii53 0:78a2573ad768 79 // flip wave form so that we can detect valley with peak detector
zinnetyazicii53 0:78a2573ad768 80 for ( i=0 ; i<BUFFER_SIZE-HAMMING_SIZE-MA4_SIZE-2 ;i++){
zinnetyazicii53 0:78a2573ad768 81 s= 0;
zinnetyazicii53 0:78a2573ad768 82 for( k=i; k<i+ HAMMING_SIZE ;k++){
zinnetyazicii53 0:78a2573ad768 83 s -= an_dx[k] *auw_hamm[k-i] ;
zinnetyazicii53 0:78a2573ad768 84 }
zinnetyazicii53 0:78a2573ad768 85 an_dx[i]= s/ (int32_t)1146; // divide by sum of auw_hamm
zinnetyazicii53 0:78a2573ad768 86 }
zinnetyazicii53 0:78a2573ad768 87
zinnetyazicii53 0:78a2573ad768 88
zinnetyazicii53 0:78a2573ad768 89 n_th1=0; // threshold calculation
zinnetyazicii53 0:78a2573ad768 90 for ( k=0 ; k<BUFFER_SIZE-HAMMING_SIZE ;k++){
zinnetyazicii53 0:78a2573ad768 91 n_th1 += ((an_dx[k]>0)? an_dx[k] : ((int32_t)0-an_dx[k])) ;
zinnetyazicii53 0:78a2573ad768 92 }
zinnetyazicii53 0:78a2573ad768 93 n_th1= n_th1/ ( BUFFER_SIZE-HAMMING_SIZE);
zinnetyazicii53 0:78a2573ad768 94 // peak location is acutally index for sharpest location of raw signal since we flipped the signal
zinnetyazicii53 0:78a2573ad768 95 maxim_find_peaks(an_dx_peak_locs, &n_npks, an_dx, BUFFER_SIZE-HAMMING_SIZE, n_th1, 8, 5 );//peak_height, peak_distance, max_num_peaks
zinnetyazicii53 0:78a2573ad768 96
zinnetyazicii53 0:78a2573ad768 97 n_peak_interval_sum =0;
zinnetyazicii53 0:78a2573ad768 98 if (n_npks>=2){
zinnetyazicii53 0:78a2573ad768 99 for (k=1; k<n_npks; k++)
zinnetyazicii53 0:78a2573ad768 100 n_peak_interval_sum += (an_dx_peak_locs[k]-an_dx_peak_locs[k -1]);
zinnetyazicii53 0:78a2573ad768 101 n_peak_interval_sum=n_peak_interval_sum/(n_npks-1);
zinnetyazicii53 0:78a2573ad768 102 *pn_heart_rate=(int32_t)(6000/n_peak_interval_sum);// beats per minutes
zinnetyazicii53 0:78a2573ad768 103 *pch_hr_valid = 1;
zinnetyazicii53 0:78a2573ad768 104 }
zinnetyazicii53 0:78a2573ad768 105 else {
zinnetyazicii53 0:78a2573ad768 106 *pn_heart_rate = -999;
zinnetyazicii53 0:78a2573ad768 107 *pch_hr_valid = 0;
zinnetyazicii53 0:78a2573ad768 108 }
zinnetyazicii53 0:78a2573ad768 109
zinnetyazicii53 0:78a2573ad768 110 for ( k=0 ; k<n_npks ;k++)
zinnetyazicii53 0:78a2573ad768 111 an_ir_valley_locs[k]=an_dx_peak_locs[k]+HAMMING_SIZE/2;
zinnetyazicii53 0:78a2573ad768 112
zinnetyazicii53 0:78a2573ad768 113
zinnetyazicii53 0:78a2573ad768 114 // raw value : RED(=y) and IR(=X)
zinnetyazicii53 0:78a2573ad768 115 // we need to assess DC and AC value of ir and red PPG.
zinnetyazicii53 0:78a2573ad768 116 for (k=0 ; k<n_ir_buffer_length ; k++ ) {
zinnetyazicii53 0:78a2573ad768 117 an_x[k] = pun_ir_buffer[k] ;
zinnetyazicii53 0:78a2573ad768 118 an_y[k] = pun_red_buffer[k] ;
zinnetyazicii53 0:78a2573ad768 119 }
zinnetyazicii53 0:78a2573ad768 120
zinnetyazicii53 0:78a2573ad768 121 // find precise min near an_ir_valley_locs
zinnetyazicii53 0:78a2573ad768 122 n_exact_ir_valley_locs_count =0;
zinnetyazicii53 0:78a2573ad768 123 for(k=0 ; k<n_npks ;k++){
zinnetyazicii53 0:78a2573ad768 124 un_only_once =1;
zinnetyazicii53 0:78a2573ad768 125 m=an_ir_valley_locs[k];
zinnetyazicii53 0:78a2573ad768 126 n_c_min= 16777216;//2^24;
zinnetyazicii53 0:78a2573ad768 127 if (m+5 < BUFFER_SIZE-HAMMING_SIZE && m-5 >0){
zinnetyazicii53 0:78a2573ad768 128 for(i= m-5;i<m+5; i++)
zinnetyazicii53 0:78a2573ad768 129 if (an_x[i]<n_c_min){
zinnetyazicii53 0:78a2573ad768 130 if (un_only_once >0){
zinnetyazicii53 0:78a2573ad768 131 un_only_once =0;
zinnetyazicii53 0:78a2573ad768 132 }
zinnetyazicii53 0:78a2573ad768 133 n_c_min= an_x[i] ;
zinnetyazicii53 0:78a2573ad768 134 an_exact_ir_valley_locs[k]=i;
zinnetyazicii53 0:78a2573ad768 135 }
zinnetyazicii53 0:78a2573ad768 136 if (un_only_once ==0)
zinnetyazicii53 0:78a2573ad768 137 n_exact_ir_valley_locs_count ++ ;
zinnetyazicii53 0:78a2573ad768 138 }
zinnetyazicii53 0:78a2573ad768 139 }
zinnetyazicii53 0:78a2573ad768 140 if (n_exact_ir_valley_locs_count <2 ){
zinnetyazicii53 0:78a2573ad768 141 *pn_spo2 = -999 ; // do not use SPO2 since signal ratio is out of range
zinnetyazicii53 0:78a2573ad768 142 *pch_spo2_valid = 0;
zinnetyazicii53 0:78a2573ad768 143 return;
zinnetyazicii53 0:78a2573ad768 144 }
zinnetyazicii53 0:78a2573ad768 145 // 4 pt MA
zinnetyazicii53 0:78a2573ad768 146 for(k=0; k< BUFFER_SIZE-MA4_SIZE; k++){
zinnetyazicii53 0:78a2573ad768 147 an_x[k]=( an_x[k]+an_x[k+1]+ an_x[k+2]+ an_x[k+3])/(int32_t)4;
zinnetyazicii53 0:78a2573ad768 148 an_y[k]=( an_y[k]+an_y[k+1]+ an_y[k+2]+ an_y[k+3])/(int32_t)4;
zinnetyazicii53 0:78a2573ad768 149 }
zinnetyazicii53 0:78a2573ad768 150
zinnetyazicii53 0:78a2573ad768 151 //using an_exact_ir_valley_locs , find ir-red DC andir-red AC for SPO2 calibration ratio
zinnetyazicii53 0:78a2573ad768 152 //finding AC/DC maximum of raw ir * red between two valley locations
zinnetyazicii53 0:78a2573ad768 153 n_ratio_average =0;
zinnetyazicii53 0:78a2573ad768 154 n_i_ratio_count =0;
zinnetyazicii53 0:78a2573ad768 155
zinnetyazicii53 0:78a2573ad768 156 for(k=0; k< 5; k++) an_ratio[k]=0;
zinnetyazicii53 0:78a2573ad768 157 for (k=0; k< n_exact_ir_valley_locs_count; k++){
zinnetyazicii53 0:78a2573ad768 158 if (an_exact_ir_valley_locs[k] > BUFFER_SIZE ){
zinnetyazicii53 0:78a2573ad768 159 *pn_spo2 = -999 ; // do not use SPO2 since valley loc is out of range
zinnetyazicii53 0:78a2573ad768 160 *pch_spo2_valid = 0;
zinnetyazicii53 0:78a2573ad768 161 return;
zinnetyazicii53 0:78a2573ad768 162 }
zinnetyazicii53 0:78a2573ad768 163 }
zinnetyazicii53 0:78a2573ad768 164 // find max between two valley locations
zinnetyazicii53 0:78a2573ad768 165 // and use ratio betwen AC compoent of Ir & Red and DC compoent of Ir & Red for SPO2
zinnetyazicii53 0:78a2573ad768 166
zinnetyazicii53 0:78a2573ad768 167 for (k=0; k< n_exact_ir_valley_locs_count-1; k++){
zinnetyazicii53 0:78a2573ad768 168 n_y_dc_max= -16777216 ;
zinnetyazicii53 0:78a2573ad768 169 n_x_dc_max= - 16777216;
zinnetyazicii53 0:78a2573ad768 170 if (an_exact_ir_valley_locs[k+1]-an_exact_ir_valley_locs[k] >10){
zinnetyazicii53 0:78a2573ad768 171 for (i=an_exact_ir_valley_locs[k]; i< an_exact_ir_valley_locs[k+1]; i++){
zinnetyazicii53 0:78a2573ad768 172 if (an_x[i]> n_x_dc_max) {n_x_dc_max =an_x[i];n_x_dc_max_idx =i; }
zinnetyazicii53 0:78a2573ad768 173 if (an_y[i]> n_y_dc_max) {n_y_dc_max =an_y[i];n_y_dc_max_idx=i;}
zinnetyazicii53 0:78a2573ad768 174 }
zinnetyazicii53 0:78a2573ad768 175 n_y_ac= (an_y[an_exact_ir_valley_locs[k+1]] - an_y[an_exact_ir_valley_locs[k] ] )*(n_y_dc_max_idx -an_exact_ir_valley_locs[k]); //red
zinnetyazicii53 0:78a2573ad768 176 n_y_ac= an_y[an_exact_ir_valley_locs[k]] + n_y_ac/ (an_exact_ir_valley_locs[k+1] - an_exact_ir_valley_locs[k]) ;
zinnetyazicii53 0:78a2573ad768 177
zinnetyazicii53 0:78a2573ad768 178
zinnetyazicii53 0:78a2573ad768 179 n_y_ac= an_y[n_y_dc_max_idx] - n_y_ac; // subracting linear DC compoenents from raw
zinnetyazicii53 0:78a2573ad768 180 n_x_ac= (an_x[an_exact_ir_valley_locs[k+1]] - an_x[an_exact_ir_valley_locs[k] ] )*(n_x_dc_max_idx -an_exact_ir_valley_locs[k]); // ir
zinnetyazicii53 0:78a2573ad768 181 n_x_ac= an_x[an_exact_ir_valley_locs[k]] + n_x_ac/ (an_exact_ir_valley_locs[k+1] - an_exact_ir_valley_locs[k]);
zinnetyazicii53 0:78a2573ad768 182 n_x_ac= an_x[n_y_dc_max_idx] - n_x_ac; // subracting linear DC compoenents from raw
zinnetyazicii53 0:78a2573ad768 183 n_nume=( n_y_ac *n_x_dc_max)>>7 ; //prepare X100 to preserve floating value
zinnetyazicii53 0:78a2573ad768 184 n_denom= ( n_x_ac *n_y_dc_max)>>7;
zinnetyazicii53 0:78a2573ad768 185 if (n_denom>0 && n_i_ratio_count <5 && n_nume != 0)
zinnetyazicii53 0:78a2573ad768 186 {
zinnetyazicii53 0:78a2573ad768 187 an_ratio[n_i_ratio_count]= (n_nume*100)/n_denom ; //formular is ( n_y_ac *n_x_dc_max) / ( n_x_ac *n_y_dc_max) ;
zinnetyazicii53 0:78a2573ad768 188 n_i_ratio_count++;
zinnetyazicii53 0:78a2573ad768 189 }
zinnetyazicii53 0:78a2573ad768 190 }
zinnetyazicii53 0:78a2573ad768 191 }
zinnetyazicii53 0:78a2573ad768 192
zinnetyazicii53 0:78a2573ad768 193 maxim_sort_ascend(an_ratio, n_i_ratio_count);
zinnetyazicii53 0:78a2573ad768 194 n_middle_idx= n_i_ratio_count/2;
zinnetyazicii53 0:78a2573ad768 195
zinnetyazicii53 0:78a2573ad768 196 if (n_middle_idx >1)
zinnetyazicii53 0:78a2573ad768 197 n_ratio_average =( an_ratio[n_middle_idx-1] +an_ratio[n_middle_idx])/2; // use median
zinnetyazicii53 0:78a2573ad768 198 else
zinnetyazicii53 0:78a2573ad768 199 n_ratio_average = an_ratio[n_middle_idx ];
zinnetyazicii53 0:78a2573ad768 200
zinnetyazicii53 0:78a2573ad768 201 if( n_ratio_average>2 && n_ratio_average <184){
zinnetyazicii53 0:78a2573ad768 202 n_spo2_calc= uch_spo2_table[n_ratio_average] ;
zinnetyazicii53 0:78a2573ad768 203 *pn_spo2 = n_spo2_calc ;
zinnetyazicii53 0:78a2573ad768 204 *pch_spo2_valid = 1;// float_SPO2 = -45.060*n_ratio_average* n_ratio_average/10000 + 30.354 *n_ratio_average/100 + 94.845 ; // for comparison with table
zinnetyazicii53 0:78a2573ad768 205 }
zinnetyazicii53 0:78a2573ad768 206 else{
zinnetyazicii53 0:78a2573ad768 207 *pn_spo2 = -999 ; // do not use SPO2 since signal ratio is out of range
zinnetyazicii53 0:78a2573ad768 208 *pch_spo2_valid = 0;
zinnetyazicii53 0:78a2573ad768 209 }
zinnetyazicii53 0:78a2573ad768 210 }
zinnetyazicii53 0:78a2573ad768 211
zinnetyazicii53 0:78a2573ad768 212
zinnetyazicii53 0:78a2573ad768 213 void spo2_algorithm::maxim_find_peaks(int32_t *pn_locs, int32_t *pn_npks, int32_t *pn_x, int32_t n_size, int32_t n_min_height, int32_t n_min_distance, int32_t n_max_num)
zinnetyazicii53 0:78a2573ad768 214 /**
zinnetyazicii53 0:78a2573ad768 215 * \brief Find peaks
zinnetyazicii53 0:78a2573ad768 216 * \par Details
zinnetyazicii53 0:78a2573ad768 217 * Find at most MAX_NUM peaks above MIN_HEIGHT separated by at least MIN_DISTANCE
zinnetyazicii53 0:78a2573ad768 218 *
zinnetyazicii53 0:78a2573ad768 219 * \retval None
zinnetyazicii53 0:78a2573ad768 220 */
zinnetyazicii53 0:78a2573ad768 221 {
zinnetyazicii53 0:78a2573ad768 222 maxim_peaks_above_min_height( pn_locs, pn_npks, pn_x, n_size, n_min_height );
zinnetyazicii53 0:78a2573ad768 223 maxim_remove_close_peaks( pn_locs, pn_npks, pn_x, n_min_distance );
zinnetyazicii53 0:78a2573ad768 224 *pn_npks = min( *pn_npks, n_max_num );
zinnetyazicii53 0:78a2573ad768 225 }
zinnetyazicii53 0:78a2573ad768 226
zinnetyazicii53 0:78a2573ad768 227 void spo2_algorithm::maxim_peaks_above_min_height(int32_t *pn_locs, int32_t *pn_npks, int32_t *pn_x, int32_t n_size, int32_t n_min_height)
zinnetyazicii53 0:78a2573ad768 228 /**
zinnetyazicii53 0:78a2573ad768 229 * \brief Find peaks above n_min_height
zinnetyazicii53 0:78a2573ad768 230 * \par Details
zinnetyazicii53 0:78a2573ad768 231 * Find all peaks above MIN_HEIGHT
zinnetyazicii53 0:78a2573ad768 232 *
zinnetyazicii53 0:78a2573ad768 233 * \retval None
zinnetyazicii53 0:78a2573ad768 234 */
zinnetyazicii53 0:78a2573ad768 235 {
zinnetyazicii53 0:78a2573ad768 236 int32_t i = 1, n_width;
zinnetyazicii53 0:78a2573ad768 237 *pn_npks = 0;
zinnetyazicii53 0:78a2573ad768 238
zinnetyazicii53 0:78a2573ad768 239 while (i < n_size-1){
zinnetyazicii53 0:78a2573ad768 240 if (pn_x[i] > n_min_height && pn_x[i] > pn_x[i-1]){ // find left edge of potential peaks
zinnetyazicii53 0:78a2573ad768 241 n_width = 1;
zinnetyazicii53 0:78a2573ad768 242 while (i+n_width < n_size && pn_x[i] == pn_x[i+n_width]) // find flat peaks
zinnetyazicii53 0:78a2573ad768 243 n_width++;
zinnetyazicii53 0:78a2573ad768 244 if (pn_x[i] > pn_x[i+n_width] && (*pn_npks) < 15 ){ // find right edge of peaks
zinnetyazicii53 0:78a2573ad768 245 pn_locs[(*pn_npks)++] = i;
zinnetyazicii53 0:78a2573ad768 246 // for flat peaks, peak location is left edge
zinnetyazicii53 0:78a2573ad768 247 i += n_width+1;
zinnetyazicii53 0:78a2573ad768 248 }
zinnetyazicii53 0:78a2573ad768 249 else
zinnetyazicii53 0:78a2573ad768 250 i += n_width;
zinnetyazicii53 0:78a2573ad768 251 }
zinnetyazicii53 0:78a2573ad768 252 else
zinnetyazicii53 0:78a2573ad768 253 i++;
zinnetyazicii53 0:78a2573ad768 254 }
zinnetyazicii53 0:78a2573ad768 255 }
zinnetyazicii53 0:78a2573ad768 256
zinnetyazicii53 0:78a2573ad768 257
zinnetyazicii53 0:78a2573ad768 258 void spo2_algorithm::maxim_remove_close_peaks(int32_t *pn_locs, int32_t *pn_npks, int32_t *pn_x,int32_t n_min_distance)
zinnetyazicii53 0:78a2573ad768 259 /**
zinnetyazicii53 0:78a2573ad768 260 * \brief Remove peaks
zinnetyazicii53 0:78a2573ad768 261 * \par Details
zinnetyazicii53 0:78a2573ad768 262 * Remove peaks separated by less than MIN_DISTANCE
zinnetyazicii53 0:78a2573ad768 263 *
zinnetyazicii53 0:78a2573ad768 264 * \retval None
zinnetyazicii53 0:78a2573ad768 265 */
zinnetyazicii53 0:78a2573ad768 266 {
zinnetyazicii53 0:78a2573ad768 267
zinnetyazicii53 0:78a2573ad768 268 int32_t i, j, n_old_npks, n_dist;
zinnetyazicii53 0:78a2573ad768 269
zinnetyazicii53 0:78a2573ad768 270 /* Order peaks from large to small */
zinnetyazicii53 0:78a2573ad768 271 maxim_sort_indices_descend( pn_x, pn_locs, *pn_npks );
zinnetyazicii53 0:78a2573ad768 272
zinnetyazicii53 0:78a2573ad768 273 for ( i = -1; i < *pn_npks; i++ ){
zinnetyazicii53 0:78a2573ad768 274 n_old_npks = *pn_npks;
zinnetyazicii53 0:78a2573ad768 275 *pn_npks = i+1;
zinnetyazicii53 0:78a2573ad768 276 for ( j = i+1; j < n_old_npks; j++ ){
zinnetyazicii53 0:78a2573ad768 277 n_dist = pn_locs[j] - ( i == -1 ? -1 : pn_locs[i] ); // lag-zero peak of autocorr is at index -1
zinnetyazicii53 0:78a2573ad768 278 if ( n_dist > n_min_distance || n_dist < -n_min_distance )
zinnetyazicii53 0:78a2573ad768 279 pn_locs[(*pn_npks)++] = pn_locs[j];
zinnetyazicii53 0:78a2573ad768 280 }
zinnetyazicii53 0:78a2573ad768 281 }
zinnetyazicii53 0:78a2573ad768 282
zinnetyazicii53 0:78a2573ad768 283 // Resort indices longo ascending order
zinnetyazicii53 0:78a2573ad768 284 maxim_sort_ascend( pn_locs, *pn_npks );
zinnetyazicii53 0:78a2573ad768 285 }
zinnetyazicii53 0:78a2573ad768 286
zinnetyazicii53 0:78a2573ad768 287 void spo2_algorithm::maxim_sort_ascend(int32_t *pn_x,int32_t n_size)
zinnetyazicii53 0:78a2573ad768 288 /**
zinnetyazicii53 0:78a2573ad768 289 * \brief Sort array
zinnetyazicii53 0:78a2573ad768 290 * \par Details
zinnetyazicii53 0:78a2573ad768 291 * Sort array in ascending order (insertion sort algorithm)
zinnetyazicii53 0:78a2573ad768 292 *
zinnetyazicii53 0:78a2573ad768 293 * \retval None
zinnetyazicii53 0:78a2573ad768 294 */
zinnetyazicii53 0:78a2573ad768 295 {
zinnetyazicii53 0:78a2573ad768 296 int32_t i, j, n_temp;
zinnetyazicii53 0:78a2573ad768 297 for (i = 1; i < n_size; i++) {
zinnetyazicii53 0:78a2573ad768 298 n_temp = pn_x[i];
zinnetyazicii53 0:78a2573ad768 299 for (j = i; j > 0 && n_temp < pn_x[j-1]; j--)
zinnetyazicii53 0:78a2573ad768 300 pn_x[j] = pn_x[j-1];
zinnetyazicii53 0:78a2573ad768 301 pn_x[j] = n_temp;
zinnetyazicii53 0:78a2573ad768 302 }
zinnetyazicii53 0:78a2573ad768 303 }
zinnetyazicii53 0:78a2573ad768 304
zinnetyazicii53 0:78a2573ad768 305 void spo2_algorithm::maxim_sort_indices_descend(int32_t *pn_x, int32_t *pn_indx, int32_t n_size)
zinnetyazicii53 0:78a2573ad768 306 /**
zinnetyazicii53 0:78a2573ad768 307 * \brief Sort indices
zinnetyazicii53 0:78a2573ad768 308 * \par Details
zinnetyazicii53 0:78a2573ad768 309 * Sort indices according to descending order (insertion sort algorithm)
zinnetyazicii53 0:78a2573ad768 310 *
zinnetyazicii53 0:78a2573ad768 311 * \retval None
zinnetyazicii53 0:78a2573ad768 312 */
zinnetyazicii53 0:78a2573ad768 313 {
zinnetyazicii53 0:78a2573ad768 314 int32_t i, j, n_temp;
zinnetyazicii53 0:78a2573ad768 315 for (i = 1; i < n_size; i++) {
zinnetyazicii53 0:78a2573ad768 316 n_temp = pn_indx[i];
zinnetyazicii53 0:78a2573ad768 317 for (j = i; j > 0 && pn_x[n_temp] > pn_x[pn_indx[j-1]]; j--)
zinnetyazicii53 0:78a2573ad768 318 pn_indx[j] = pn_indx[j-1];
zinnetyazicii53 0:78a2573ad768 319 pn_indx[j] = n_temp;
zinnetyazicii53 0:78a2573ad768 320 }
zinnetyazicii53 0:78a2573ad768 321 }