Inital commit (1.0)

CMakeLists.txt

+cmake_minimum_required(VERSION 3.19)
+
+project(relaxisloader LANGUAGES C CXX)
+
+set(SRC_FILES
+	relaxisloader.c
+	utils.c
+)
+
+set(API_HEADERS_DIR relaxisloader/)
+
+set(API_HEADERS_C
+	${API_HEADERS_DIR}/relaxisloader.h
+)
+
+find_package(PkgConfig REQUIRED)
+find_package(Doxygen)
+pkg_check_modules(SQL REQUIRED sqlite3)
+
+add_library(${PROJECT_NAME} SHARED ${SRC_FILES} ${API_HEADERS_C})
+target_link_libraries(${PROJECT_NAME} ${SQL_LIBRARIES})
+target_include_directories(${PROJECT_NAME} PUBLIC ./${API_HEADERS_DIR} ${SQL_INCLUDE_DIRS})
+set_target_properties(${PROJECT_NAME} PROPERTIES COMPILE_FLAGS "-Wall -O2 -march=native -g" LINK_FLAGS "-flto -pthread")
+target_compile_definitions(${PROJECT_NAME} PRIVATE _XOPEN_SOURCE)
+
+if(CMAKE_INSTALL_PREFIX_INITIALIZED_TO_DEFAULT)
+	set(CMAKE_INSTALL_PREFIX "/usr" CACHE PATH "..." FORCE)
+endif(CMAKE_INSTALL_PREFIX_INITIALIZED_TO_DEFAULT)
+
+install(TARGETS ${PROJECT_NAME} DESTINATION lib)
+install(FILES ${API_HEADERS_C} DESTINATION include/${PROJECT_NAME})
+
+link_directories(${CMAKE_CURRENT_BINARY_DIR})
+set(SRC_FILES_TEST_APP main.c)
+set(LIBS_TEST -L. -l${PROJECT_NAME})
+add_executable(${PROJECT_NAME}_test ${SRC_FILES_TEST_APP})
+add_dependencies(${PROJECT_NAME}_test ${PROJECT_NAME})
+target_link_libraries(${PROJECT_NAME}_test ${LIBS_TEST})
+target_include_directories(${PROJECT_NAME}_test PUBLIC ./${API_HEADERS_DIR})
+set_target_properties(${PROJECT_NAME}_test PROPERTIES COMPILE_FLAGS "-Wall -O2 -march=native -g" LINK_FLAGS "-flto")
+install(TARGETS ${PROJECT_NAME}_test DESTINATION bin)
+
+if (DOXYGEN_FOUND)
+	set(DOXYGEN_IN ${CMAKE_CURRENT_SOURCE_DIR}/doc/librelaxisloader.doxygen.in)
+	set(DOXYGEN_OUT ${CMAKE_CURRENT_BINARY_DIR}/doc/librelaxisloader.doxygen)
+	configure_file(${DOXYGEN_IN} ${DOXYGEN_OUT} @ONLY)
+	message("Doxygen build started")
+
+	add_custom_target(doc
+		COMMAND ${DOXYGEN_EXECUTABLE} ${DOXYGEN_OUT}
+		WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
+		COMMENT "Generating API documentation with Doxygen"
+		VERBATIM )
+else (DOXYGEN_FOUND)
+  message("Doxygen needs to be installed to generate the doxygen documentation")
+endif (DOXYGEN_FOUND)

README.md

+# librelaxisloader
+
+librelaxisloader is a shared library that allows you to load data from RelaxIS3 files. This library supports only files with a DatabaseFormat of "1"
+
+For questions or comments, please write to klemm@rhd-instruments.de
+
+Full API documentation can be built with the "doc" target and is also avialable [here](http://uvos.xyz/kiss/librelaxisloaderdoc)
+
+## Compile/Install
+
+### Requirements
+
+* git
+* c99 capable compiler (GCC, CLANG)
+* cmake 3.20 or later
+* curl 7.64 or later
+* (optinal) doxygen 1.8 or later to generate the documentation
+
+### Procedure
+
+In a console do:
+
+* git clone https://git-ce.rwth-aachen.de/carl_philipp.klemm/librelaxisloader.git
+* cd librelaxisloader
+* mkdir build
+* cd build
+* cmake ..
+* make
+* sudo make install

doc/DoxygenLayout.xml

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+    <tab type="files" visible="yes" title="">
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+    </tab>
+    <tab type="examples" visible="yes" title="" intro=""/>  
+  </navindex>
+
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doc/mainpage.txt

+/*! \mainpage librelaxisloader manual
+
+librelaxisloader is a shared library that allows you to load data from RelaxIS3 files. This library supports only files with DatabaseFormat of "1"
+
+An API referance can be found here: \subpage API
+*/

main.c

+#include <stdio.h>
+#include <relaxisloader.h>
+#include <stdlib.h>
+
+int main(int argc, char** argv)
+{
+	if(argc < 2) {
+		printf("Usage %s [FILE]\n", argc == 1 ? argv[0] : "NULL");
+		return 1;
+	}
+
+	const char *error;
+	struct rxfile *file = rlx_open_file(argv[1], &error);
+	if(!file) {
+		printf("Unable to open %s: %s\n", argv[1], error);
+		return 2;
+	}
+
+	size_t projectCount;
+	struct rlx_project** projects = rlx_get_projects(file, &projectCount);
+	if(projectCount < 1) {
+		printf("File contains no projects: %s\n", rlx_get_errnum_str(rlx_get_errnum(file)));
+		return 4;
+	}
+
+	size_t idCount;
+	int *ids = rlx_get_spectra_ids(file, projects[0], &idCount);
+	for(int i = 0; i < idCount; ++i)
+		printf("PROJECT: %d ID: %d\n", projects[0]->id, ids[i]);
+	if(idCount < 1) {
+		printf("No spectra in project %d: %s\n", projects[0]->id, rlx_get_errnum_str(rlx_get_errnum(file)));
+		return 3;
+	}
+
+	printf("%p %d\n", projects[0], projects[0]->id);
+	struct rlx_spectra* spectra = rlx_get_spectra(file, projects[0], ids[0]);
+	if(!spectra) {
+		printf("Could not load spectra for %d %d: %s\n", projects[0]->id, ids[0], rlx_get_errnum_str(rlx_get_errnum(file)));
+		return 3;
+	}
+	printf("Spectra for PROJECT: %d ID: %d\nomega, re, im\n", projects[0]->id, ids[0]);
+	for(size_t i = 0; i < spectra->length; ++i) {
+		printf("%f,%f,%f\n", spectra->datapoints[i].omega, spectra->datapoints[i].re, spectra->datapoints[i].im);
+	}
+
+	size_t paramCount;
+	struct rlx_fitparam** params = rlx_get_fit_parameters(file, projects[0], ids[0], &paramCount);
+	if(!params) {
+		printf("Could not get parameters for project %d spectra %d: %s\n", projects[0]->id, ids[0], rlx_get_errnum_str(rlx_get_errnum(file)));
+		return 4;
+	}
+	for(size_t i = 0; i < paramCount; ++i) {
+		printf("Parameter %d: Name: %s Value: %f Error: %f\n", params[i]->p_index, params[i]->name, params[i]->value, params[i]->error);
+	}
+
+	rlx_project_free_array(projects);
+	rlx_spectra_free(spectra);
+	rlx_fitparam_free_array(params);
+	free(ids);
+	rlx_close_file(file);
+	return 0;
+}

relaxisloader.c

+#include "relaxisloader.h"
+
+#include <stdlib.h>
+#include <math.h>
+#include <sqlite3.h>
+#include <assert.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "utils.h"
+
+struct rxfile
+{
+	int error;
+	sqlite3 *db;
+};
+
+/**
+ * @brief Frees a project struct
+ *
+ * @param proj project struct to be freed, or NULL
+ */
+void rlx_project_free(struct rlx_project* proj)
+{
+	if(!proj)
+		return;
+	if(proj->name)
+		free(proj->name);
+	free(proj);
+}
+
+void rlx_project_free_array(struct rlx_project** proj)
+{
+	struct rlx_project** firstproj = proj;
+	while(*proj) {
+		rlx_project_free(*proj);
+		++proj;
+	}
+	free(firstproj);
+}
+
+void rlx_spectra_free(struct rlx_spectra* specta)
+{
+	if(!specta)
+		return;
+
+	if(specta->circuit)
+		free(specta->circuit);
+	free(specta->datapoints);
+	free(specta);
+}
+
+void rlx_spectra_free_array(struct rlx_spectra** specta)
+{
+	struct rlx_spectra** firstspectra = specta;
+	while(*specta) {
+		rlx_spectra_free(*specta);
+		++specta;
+	}
+	free(firstspectra);
+}
+
+void rlx_fitparam_free(struct rlx_fitparam* param)
+{
+	if(!param)
+		return;
+	if(param->name)
+		free(param->name);
+	free(param);
+}
+
+void rlx_fitparam_free_array(struct rlx_fitparam** param)
+{
+	struct rlx_fitparam** firstparam = param;
+	while(*param) {
+		rlx_fitparam_free(*param);
+		++param;
+	}
+	free(firstparam);
+}
+
+struct rxfile* rlx_open_file(const char* path, const char** error)
+{
+	struct rxfile *file = calloc(1, sizeof(*file));
+	int ret = sqlite3_open_v2(path, &file->db, SQLITE_OPEN_READONLY, NULL);
+	if(!(ret == SQLITE_OK || ret == SQLITE_DONE)) {
+		if(error)
+			*error = sqlite3_errstr(ret);
+		free(file);
+		return NULL;
+	}
+
+	const char *req = "SELECT Value FROM Properties WHERE Name=\"DatabaseFormat\"";
+	sqlite3_stmt *ppStmt;
+	ret = sqlite3_prepare_v2(file->db, req, strlen(req), &ppStmt, NULL);
+	if(ret != SQLITE_OK) {
+		if(error)
+			*error = "Unable to read file version";
+		return NULL;
+	}
+
+	ret = sqlite3_step(ppStmt);
+	if((ret != SQLITE_OK && ret != SQLITE_DONE && ret != SQLITE_ROW) || sqlite3_column_count(ppStmt) != 1) {
+		if(error)
+			*error = "Unable to read file version, field missing";
+		return NULL;
+	}
+
+	int version = sqlite3_column_int(ppStmt, 0);
+	if(version != 1) {
+		if(error)
+			*error = "Unsupported file version";
+		return NULL;
+	}
+
+	if(error)
+		*error = NULL;
+
+	sqlite3_finalize(ppStmt);
+	return file;
+}
+
+void rlx_close_file(struct rxfile* file)
+{
+	sqlite3_close(file->db);
+	free(file);
+}
+
+struct rlx_project** rlx_get_projects(struct rxfile* file, size_t* length)
+{
+	char **table;
+	int rows;
+	int cols;
+	char *error;
+	int ret = sqlite3_get_table(file->db, "SELECT ID,NAME,DATE FROM Projects", &table, &rows, &cols, &error);
+
+	if(ret != SQLITE_OK) {
+		file->error = ret;
+		free(error);
+		if(length)
+			*length = 0;
+		return NULL;
+	}
+	rows++;
+	assert(cols == 3);
+
+	struct rlx_project **projects = malloc(sizeof(*projects)*(rows));
+	assert(projects);
+
+	if(length)
+		*length = rows-1;
+
+	for(int i = 1; i < rows; ++i) {
+		projects[i-1] = malloc(sizeof(struct rlx_project));
+		assert(projects[i-1]);
+		projects[i-1]->name = rlx_strdup(table[i*cols+1]);
+		int ret = sscanf(table[i*cols], "%d", &projects[i-1]->id);
+		assert(ret == 1);
+		projects[i-1]->date = rlx_str_to_time(table[i*cols+2]);
+	}
+	projects[rows-1] = NULL;
+
+	sqlite3_free_table(table);
+	return projects;
+}
+
+static struct rlx_datapoint* rlx_get_datapoints(struct rxfile* file, int id, size_t *length)
+{
+	char **table;
+	int rows;
+	int cols;
+	char *error;
+	char *req = rlx_alloc_printf("SELECT frequency,zreal,zimag FROM Datapoints WHERE file_id=%d", id);
+	int ret = sqlite3_get_table(file->db, req, &table, &rows, &cols, &error);
+	free(req);
+	++rows;
+	if(ret != SQLITE_OK) {
+		file->error = ret;
+		free(error);
+		if(length)
+			*length = 0;
+		return NULL;
+	}
+	assert(cols == 3);
+
+	if(rows < 2) {
+		file->error = -100;
+		sqlite3_free_table(table);
+		return NULL;
+	}
+
+	if(length)
+		*length = rows-1;
+	struct rlx_datapoint *out = malloc(sizeof(*out)*(rows-1));
+
+	for(int i = 1; i < rows; ++i) {
+		int ret = sscanf(table[i*cols], "%lf", &out[i-1].omega);
+		assert(ret == 1);
+		out[i-1].omega *= 2*M_PI;
+		ret = sscanf(table[i*cols+1], "%lf", &out[i-1].re);
+		assert(ret == 1);
+		ret = sscanf(table[i*cols+2], "%lf", &out[i-1].im);
+		assert(ret == 1);
+	}
+	sqlite3_free_table(table);
+	return out;
+}
+
+struct rlx_spectra* rlx_get_spectra(struct rxfile* file, const struct rlx_project* project, int id)
+{
+	char **table;
+	int rows;
+	int cols;
+	char *error;
+	char *req = rlx_alloc_printf(
+		"SELECT groupname,fitted,lowfreqlimit,highfreqlimit,dateadded,datefitted FROM Files WHERE project_id=%d AND ID=%d",
+		project->id, id);
+	int ret = sqlite3_get_table(file->db, req, &table, &rows, &cols, &error);
+	free(req);
+	++rows;
+	if(ret != SQLITE_OK) {
+		file->error = ret;
+		free(error);
+		return NULL;
+	}
+
+	if(rows < 2) {
+		file->error = -100;
+		sqlite3_free_table(table);
+		return NULL;
+	}
+
+	assert(cols == 6);
+
+	struct rlx_spectra *out = malloc(sizeof(*out));
+	out->id = id;
+	out->circuit = rlx_strdup(table[6]);
+	out->fitted = table[7][0] == '1';
+	out->project_id = project->id;
+	ret = sscanf(table[8], "%lf", &out->freq_lower_limit);
+	assert(ret == 1);
+	ret = sscanf(table[9], "%lf", &out->freq_upper_limit);
+	assert(ret == 1);
+	out->date_added  = rlx_str_to_time(table[10]);
+	out->date_fitted = rlx_str_to_time(table[11]);
+
+	out->datapoints = rlx_get_datapoints(file, id, &out->length);
+	sqlite3_free_table(table);
+	return out;
+}
+
+struct rlx_spectra** rlx_get_all_spectra(struct rxfile* file, const struct rlx_project* project)
+{
+	size_t length;
+	int *ids = rlx_get_spectra_ids(file, project, &length);
+
+	if(!ids)
+		return NULL;
+
+	struct rlx_spectra **out = malloc(sizeof(*out)*(length+1));
+	for(size_t i = 0; i < length; ++i) {
+		out[i] = rlx_get_spectra(file, project, i);
+	}
+	out[length] = NULL;
+
+	free(ids);
+	return out;
+}
+
+int* rlx_get_spectra_ids(struct rxfile* file, const struct rlx_project* project, size_t* length)
+{
+	char **table;
+	int rows;
+	int cols;
+	char *error;
+	int ret = sqlite3_get_table(file->db, "SELECT ID FROM Files;", &table, &rows, &cols, &error);
+	if(ret != SQLITE_OK) {
+		file->error = ret;
+		free(error);
+		if(length)
+			*length = 0;
+		return NULL;
+	}
+	++rows;
+	printf("%s: got %dx%d\n", __func__, rows, cols);
+	assert(cols == 1);
+
+	if(rows < 2) {
+		file->error = -100;
+		sqlite3_free_table(table);
+		return NULL;
+	}
+
+	if(length)
+		*length = rows-1;
+
+	int *ids = malloc(sizeof(*ids)*(rows-1));
+
+	for(int i = 1; i < rows; ++i) {
+		int ret = sscanf(table[i], "%d", &ids[i-1]);
+		assert(ret == 1);
+	}
+
+	sqlite3_free_table(table);
+	return ids;
+}
+
+struct rlx_fitparam** rlx_get_fit_parameters(struct rxfile* file, const struct rlx_project* project, int id, size_t *length)
+{
+	(void)project;
+	if(length)
+		*length = 0;
+	char *req = rlx_alloc_printf("SELECT pindex,name,value,error,lowerlimit,upperlimit FROM Fitparameters WHERE file_id=%d", id);
+	sqlite3_stmt *ppStmt;
+	int ret = sqlite3_prepare_v2(file->db, req, strlen(req), &ppStmt, NULL);
+	free(req);
+	if(ret != SQLITE_OK) {
+		file->error = ret;
+		return NULL;
+	}
+
+	size_t outSize = 8;
+	size_t outIndex = 0;
+	struct rlx_fitparam **out = malloc(sizeof(*out)*outSize);
+
+	while((ret = sqlite3_step(ppStmt)) == SQLITE_ROW) {
+		assert(sqlite3_column_count(ppStmt) == 6);
+		struct rlx_fitparam *param = malloc(sizeof(*param));
+		param->p_index = sqlite3_column_int(ppStmt, 0);
+		param->spectra_id = id;
+		param->name = rlx_strdup((char*)sqlite3_column_text(ppStmt, 1));
+		param->value = sqlite3_column_double(ppStmt, 2);
+		param->error = sqlite3_column_double(ppStmt, 3);
+		param->lower_limit = sqlite3_column_double(ppStmt, 4);
+		param->upper_limit = sqlite3_column_double(ppStmt, 5);
+		if(outIndex == outSize) {
+			outSize *= 2;
+			assert((out = realloc(out, sizeof(*out)*outSize)));
+		}
+		out[outIndex] = param;
+		++outIndex;
+	}
+
+	if(ret != SQLITE_OK && ret != SQLITE_DONE) {
+		free(out);
+		file->error = ret;
+		return NULL;
+	}
+
+	if(outIndex == outSize) {
+		outSize += 1;
+		assert((out = realloc(out, sizeof(*out)*outSize)));
+	}
+	out[outIndex] = NULL;
+
+	if(length)
+		*length = outIndex;
+	file->error = sqlite3_finalize(ppStmt);
+	return out;
+}
+
+int rlx_get_errnum(const struct rxfile* file)
+{
+	return file->error;
+}
+
+const char* rlx_get_errnum_str(int errnum)
+{
+	if(errnum == 0)
+		return "Success";
+	if(errnum > 0)
+		return sqlite3_errstr(errnum);
+	if(errnum == -100)
+		return "No sutch entry";
+	return "Unkown error";
+}
+

relaxisloader/relaxisloader.h

+/*
+ * relaxisloader.h
+ * Copyright (C) Carl Philipp Klemm 2023 <carl@uvos.xyz>
+ *
+ * relaxisloader.h is free software: you can redistribute it and/or modify it
+ * under the terms of the lesser GNU General Public License as published by the
+ * Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * relaxisloader.h is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the lesser GNU General Public License along
+ * with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+#include <stdbool.h>
+#include <time.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+Api for use by librelaxisloader users.
+* @defgroup API User API
+* This api allows you to load relaxis files and get the data therein
+* @{
+*/
+
+struct rxfile;
+
+struct rlx_project {
+	int id; /**< Project id*/
+	char* name; /**< Name of the project */
+	time_t date; /**< Project creation time*/
+};
+
+/**
+ * @brief Frees a project struct
+ *
+ * @param proj project struct to be freed, or NULL
+ */
+void rlx_project_free(struct rlx_project* proj);
+
+/**
+ * @brief Frees an array of project structs
+ *
+ * @param proj_array array of project structs to be freed
+ */
+void rlx_project_free_array(struct rlx_project** proj_array);
+
+struct rlx_datapoint {
+	double im; /**< imaginary part of the mesurement in Ohms*/
+	double re; /**< real part of the mesurement in Ohms*/
+	double omega; /**< freqency of the mesurement in rad/s*/
+};
+
+struct rlx_spectra {
+	int id; /**< Spectra id, also called "file" in relaxis*/
+
+	struct rlx_datapoint* datapoints; /**< datapoints of the spectrum*/
+	size_t length; /**< Amount of datapoints in the spectrum*/
+
+	char* circuit; /**< Relaxis circuit descriptian string*/
+	bool fitted; /**< True if circuit has been fitted to spectrum*/
+	int project_id; /**< Id of the project this spectrum belongs to*/
+	double freq_lower_limit; /**< Lower limit of freqency range of this spctrum*/
+	double freq_upper_limit; /**< Upper limit of freqency range of this spctrum*/
+	time_t date_added;
+	time_t date_fitted;
+};
+
+/**
+ * @brief Frees a spectra struct
+ *
+ * @param spectra spectra to be freed
+ */
+void rlx_spectra_free(struct rlx_spectra* spectra);
+
+/**
+ * @brief Frees an array of spectra structs
+ *
+ * @param spectra_array array of spectra structs to be freed
+ */
+void rlx_spectra_free_array(struct rlx_spectra** spectra_array);
+
+struct rlx_fitparam {
+	int spectra_id;
+	int p_index;
+	char* name;
+	double value;
+	double error;
+	double lower_limit;
+	double upper_limit;
+};
+
+/**
+ * @brief Frees a fitparam struct
+ *
+ * @param fitparam fitparam struct to be freed
+ */
+void rlx_fitparam_free(struct rlx_fitparam* param);
+
+/**
+ * @brief Frees an array of fitparam structs
+ *
+ * @param param_array array of fitparam structs to be freed
+ */
+void rlx_fitparam_free_array(struct rlx_fitparam** param_array);
+
+/**
+ * @brief Frees a project struct
+ *
+ * @param path the filesystem path where the file shal be opened
+ * @param error if an error occures and NULL is retuned, pointer to an error string is set here,
+ * owned by librelaxisloader, do not free, valid only untill next call to librelaxisloader
+ * @return a rxfile struct or NULL if opening was unsucessfull, to be closed with rlx_close_file
+ */
+struct rxfile* rlx_open_file(const char* path, const char** error);
+
+void rlx_close_file(struct rxfile* file);
+
+/**
+ * @brief Gets all the projects in a given RelaxIS file
+ *
+ * @param file file to load projects from
+ * @param length pointer to a size_t where the number of projects will be stored, or NULL
+ * @return A NULL terminated array of project structs will be allocated here, to be freed with rlx_project_free_array, or NULL on error
+ */
+struct rlx_project** rlx_get_projects(struct rxfile* file, size_t* length);
+
+/**
+ * @brief Loads all spectra from file
+ *
+ * @param file file to load spectra from
+ * @param project project to load spectra from
+ * @return A NULL terminated array of spectra structs will be allocated here, to be freed with rlx_spectra_free_array, or NULL on error
+ */
+struct rlx_spectra** rlx_get_all_spectra(struct rxfile* file, const struct rlx_project* project);
+
+/**
+ * @brief Loads a given spectra from file
+ *
+ * @param file file to load spectra from
+ * @param project project to load spectra from
+ * @param id spectra id for wich to load parameters
+ * @param length pointer to size_t where the number of ids will be stored or NULL
+ * @return A NULL terminated array of fitparam structs will be allocated here, to be freed with rlx_fitparam_free_array, or NULL on error
+ */
+int* rlx_get_spectra_ids(struct rxfile* file, const struct rlx_project* project, size_t* length);
+
+/**
+ * @brief Loads a given spectra from file
+ *
+ * @param file file to load spectra from
+ * @param project project to load spectra from
+ * @param id spectra id to load
+ * @return spectra struct or NULL if unsucessful, to be freed with rlx_spectra_free
+ */
+struct rlx_spectra* rlx_get_spectra(struct rxfile* file, const struct rlx_project* project, int id);
+
+/**
+ * @brief Loads a given spectra from file
+ *
+ * @param file file to load spectra from
+ * @param project project to load spectra from
+ * @param id spectra id for wich to load parameters
+ * @param length a pointer to a size_t where the number of parameters will be stored, or NULL
+ * @return A NULL terminated array of fitparam structs will be allocated here, to be freed with rlx_fitparam_free_array, or NULL on error
+ */
+struct rlx_fitparam** rlx_get_fit_parameters(struct rxfile* file, const struct rlx_project* project, int id, size_t *length);
+
+/**
+ * @brief Returns the last error retuned on a file operation
+ *
+ * @return relaxiloader error number
+ */
+int rlx_get_errnum(const struct rxfile* file);
+
+/**
+ * @brief Returns a human reable error string for a given error number
+ *
+ * @return Error string, owend by librelaxisloader do not free
+ */
+const char* rlx_get_errnum_str(int errnum);
+
+/**
+....
+* @}
+*/
+
+#ifdef __cplusplus
+}
+#endif

utils.c

+#include "utils.h"
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdarg.h>
+#include <stdio.h>
+
+char *rlx_strconcat(const char* a, const char* b)
+{
+	char* full_str = malloc(strlen(a)+strlen(b));
+	assert(full_str);
+	strcpy(full_str, a);
+	strcat(full_str, b);
+	return full_str;
+}
+
+char *rlx_strdup(const char* a)
+{
+	char *ret = malloc(strlen(a)+1);
+	assert(ret);
+	strcpy(ret, a);
+	return ret;
+}
+
+time_t rlx_str_to_time(const char* str)
+{
+	struct tm tm = {};
+	char *tmRet = strptime(str, "%Y-%m-%d%t%H:%M:%S", &tm);
+	assert(tmRet);
+	return mktime(&tm);
+}
+
+char *rlx_alloc_printf(const char* fmt, ...)
+{
+	va_list args;
+	va_start(args, fmt);
+	int len = vsnprintf(NULL, 0, fmt, args);
+	va_end(args);
+	char *out = malloc(len+1);
+	va_start(args, fmt);
+	vsnprintf(out, len+1, fmt, args);
+	va_end(args);
+	return out;
+}

utils.h

+#pragma once
+#include <time.h>
+
+char *rlx_strconcat(const char* a, const char* b);
+char *rlx_strdup(const char* a);
+time_t rlx_str_to_time(const char* str);
+char *rlx_alloc_printf(const char* fmt, ...) __attribute__((format(printf, 1, 2)));