Add string based constructors for UPM sensors

Signed-off-by: Mihai Stefanescu <mihai.stefanescu@rinftech.com>
Signed-off-by: Stefan Andritoiu <stefan.andritoiu@gmail.com>
Signed-off-by: Mihai Tudor Panu <mihai.tudor.panu@intel.com>

src/buzzer/buzzer.h

@@ -29,6 +29,7 @@
 
 #include <stdlib.h>
 #include <stdio.h>
+#include <string.h>
 #include <upm.h>
 
 #include <mraa/pwm.h>
@@ -110,6 +111,38 @@ extern "C" {
      */
     float buzzer_get_volume(const buzzer_context dev);
 
+    char** upm_parse_init_str(const char* str, const char* delims, int *num_tokens)
+    {
+      char *saveptr, *tok, *s, *p_str;
+      char **output = NULL;
+      size_t output_size = 0;
+
+      p_str = strdup(str);
+
+      for (s = p_str; ; s = NULL) {
+        tok = strtok_r(s, delims, &saveptr);
+        if (tok == NULL)
+          break;
+        output = (char**)realloc(output, (++output_size) * sizeof(char*));
+        output[output_size - 1] = (char*)calloc(strlen(tok) + 1, sizeof(char));
+        strncpy(output[output_size - 1], tok, strlen(tok));
+      }
+      *num_tokens = output_size;
+
+      free(p_str);
+
+      return output;
+    }
+
+    void upm_delete_parsed_str(char **str, int num_tokens)
+    {
+      for (int i = 0; i < num_tokens; ++i) {
+        free(str[i]);
+      }
+
+      free(str);
+    }
+
 #ifdef __cplusplus
 }
 #endif