--- a/th_string.c	Fri Jan 17 00:01:55 2020 +0200
+++ b/th_string.c	Fri Jan 17 03:18:40 2020 +0200
@@ -12,7 +12,10 @@
 #include "th_printf.c"
 
 
-/* Implementation of strdup() with a NULL check
+/**
+ * Implementation of strdup() with a @c NULL check.
+ * @param[in] src string to create a copy of
+ * @returns copy of the given string, or @c NULL if @p src was @c NULL or memory could not be allocated.
  */
 char *th_strdup(const char *src)
 {
@@ -31,7 +34,14 @@
 }
 
 
-/* Implementation of strndup() with NULL check
+/**
+ * Implementation of strndup() with @c NULL check. Copies up to @p n
+ * characters from the source. A NUL terminator is always added,
+ * unless @p src was @c NULL or memory could not be allocated, in which
+ * case @c NULL pointer is returned.
+ * @param[in] src string pointer to be copied from
+ * @param[in] n maximum number of characters to copy
+ * @returns the resulting string or @c NULL pointer
  */
 char *th_strndup(const char *src, const size_t n)
 {
@@ -55,9 +65,15 @@
 }
 
 
-/* Like strdup, but trims whitespace from the string according to specified flags.
- * See TH_TRIM_* in th_string.h. If the resulting string would be empty (length 0),
- * NULL is returned.
+/**
+ * Helper function for th_strdup_trim() and friends. Copies @p len characters from
+ * given string, and trims whitespace from it according to specified @p flags. 
+ * See TH_TRIM_* in th_string.h. If @p len or the resulting trimmed string would
+ * be empty (length 0), no copy is allocated and a @c NULL pointer is returned.
+ * @param[in] src source string (does not need to be NUL terminated, as length must be specified)
+ * @param[in] len length of the source string, or desired number of characters to copy at maximum
+ * @param[in] flags trimming flags, see TH_TRIM_* in th_string.h
+ * @returns the resulting string or @c NULL pointer
  */
 static char * th_strdup_trim_do(const char *src, size_t len, const int flags)
 {
@@ -93,6 +109,14 @@
 }
 
 
+/**
+ * Create copy of the given string, but trim the result according to specified @p flags.
+ * See TH_TRIM_* in th_string.h. If length the resulting trimmed string would
+ * be empty (0), no copy is allocated and a NULL pointer is returned.
+ * @param[in] src source string
+ * @param[in] flags trimming flags, see TH_TRIM_* in th_string.h
+ * @returns the resulting string or @c NULL pointer
+ */
 char *th_strdup_trim(const char *src, const int flags)
 {
     if (src == NULL)
@@ -102,6 +126,16 @@
 }
 
 
+/**
+ * Create copy of the given string @p src, up to @p n characters (or less, if the string
+ * is shorter.) The result is trimmed according to specified @p flags.
+ * See TH_TRIM_* in th_string.h. If @p n or the resulting trimmed string would
+ * be empty (length 0), no copy is allocated and a NULL pointer is returned.
+ * @param[in] src source string
+ * @param[in] n maximum number of characters to copy from the source string
+ * @param[in] flags trimming flags, see TH_TRIM_* in th_string.h
+ * @returns the resulting string or @c NULL pointer
+ */
 char *th_strndup_trim(const char *src, const size_t n, const int flags)
 {
     size_t len;
@@ -147,6 +181,14 @@
 #endif
 
 
+/**
+ * Wrapper for either libc vsnprintf() or th-libs internal
+ * vsnprintf() implementation, as determined by a compile-time define.
+ * @param[out] buf pointer to buffer to print to
+ * @param[in] size available space in the buffer in bytes
+ * @param[in] fmt format string
+ * @param[in] ap a va_list variable arguments list structure
+ */
 int th_vsnprintf(char *buf, size_t size, const char *fmt, va_list ap)
 {
 #ifdef TH_USE_INTERNAL_SPRINTF
@@ -172,6 +214,14 @@
 }
 
 
+/**
+ * Wrapper for either libc snprintf() or th-libs internal
+ * snprintf() implementation, as determined by a compile-time define.
+ * @param[out] buf pointer to buffer to print to
+ * @param[in] size available space in the buffer in bytes
+ * @param[in] fmt format string
+ * @param[in] ... variable arguments
+ */
 int th_snprintf(char *buf, size_t size, const char *fmt, ...)
 {
     int n;
@@ -253,6 +303,13 @@
 #endif
 
 
+/**
+ * Combination of vsprintf() and strdup. Automatically allocates memory
+ * for the resulting string.
+ * @param[in] fmt format string
+ * @param[in] args variable arguments list structure
+ * @returns the resulting string or @c NULL pointer in case of error
+ */
 char *th_strdup_vprintf(const char *fmt, va_list args)
 {
 #ifdef TH_USE_INTERNAL_SPRINTF
@@ -317,6 +374,13 @@
 }
 
 
+/**
+ * Combination of sprintf() and strdup. Automatically allocates memory
+ * for the resulting string.
+ * @param[in] fmt format string
+ * @param[in] ... optional printf arguments
+ * @returns the resulting string or @c NULL pointer in case of error
+ */
 char *th_strdup_printf(const char *fmt, ...)
 {
     char *res;
@@ -330,6 +394,14 @@
 }
 
 
+/**
+ * A helper function that is given a pointer to a pointer of string,
+ * which will be automatically freed (if necessary) and replaced with
+ * a pointer to the newly created string.
+ * @param[in,out] buf pointer to a char pointer/string
+ * @param[in] fmt format string
+ * @param[in] args variable arguments list structure
+ */
 void th_pstr_vprintf(char **buf, const char *fmt, va_list ap)
 {
     char *tmp = th_strdup_vprintf(fmt, ap);
@@ -338,6 +410,14 @@
 }
 
 
+/**
+ * A helper function that is given a pointer to a pointer of string,
+ * which will be automatically freed (if necessary) and replaced with
+ * a pointer to the newly created string.
+ * @param[in,out] buf pointer to a char pointer/string
+ * @param[in] fmt format string
+ * @param[in] ... optional printf arguments
+ */
 void th_pstr_printf(char **buf, const char *fmt, ...)
 {
     char *tmp;