calibration.c

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#include <stdio.h>
#include <string.h>
 
#include <unistd.h>
 
#include "log.h"
#include "rl.h"
 
#include "calibration.h"
 
rl_calibration_t rl_calibration;
 
void calibration_reset_offsets(void) {
    for (int i = 0; i < RL_CHANNEL_COUNT; i++) {
        rl_calibration.offsets[i] = 0;
    }
}
 
void calibration_reset_scales(void) {
    for (int i = 0; i < RL_CHANNEL_COUNT; i++) {
        rl_calibration.scales[i] = 1;
    }
}
 
int calibration_load(void) {
    int ret;
    char const *calibration_file_name = NULL;
 
    // check if user/system calibration file existing
    ret = access(RL_CALIBRATION_USER_FILE, R_OK);
    if (ret == 0) {
        calibration_file_name = RL_CALIBRATION_USER_FILE;
    } else {
        ret = access(RL_CALIBRATION_SYSTEM_FILE, R_OK);
        if (ret == 0) {
            calibration_file_name = RL_CALIBRATION_SYSTEM_FILE;
        } else {
            // no calibration file available
            calibration_reset_offsets();
            calibration_reset_scales();
            rl_status.calibration_time = 0;
            rl_status.calibration_file[0] = 0; // empty string
            return ERROR;
        }
    }
 
    FILE *file = fopen(calibration_file_name, "r");
    if (file == NULL) {
        // no calibration file available
        calibration_reset_offsets();
        calibration_reset_scales();
        rl_status.calibration_time = 0;
        return ERROR;
    }
 
    // read calibration
    rl_calibration_file_t calibration_file;
    fread(&calibration_file, sizeof(rl_calibration_file_t), 1, file);
 
    // check data
    if (calibration_file.file_magic != RL_CALIBRATION_FILE_MAGIC) {
        rl_log(RL_LOG_ERROR, "invalid calibration file magic %x",
               calibration_file.file_magic);
        return ERROR;
    }
    if (calibration_file.file_version != RL_CALIBRATION_FILE_VERSION) {
        rl_log(RL_LOG_ERROR, "unsupported calibration file version %d",
               calibration_file.file_version);
        return ERROR;
    }
    if (calibration_file.header_length != RL_CALIBRATION_FILE_HEADER_LENGTH) {
        rl_log(RL_LOG_ERROR, "invalid calibration file header length %d",
               calibration_file.header_length);
        return ERROR;
    }
 
    memcpy(&rl_calibration, &(calibration_file.data), sizeof(rl_calibration_t));
 
    // store calibration info information to status
    rl_status.calibration_time = calibration_file.calibration_time;
    strncpy(rl_status.calibration_file, calibration_file_name,
            sizeof(rl_status.calibration_file) - 1);
 
    // close file
    fclose(file);
 
    return SUCCESS;
}