char * strtok_P(char *__s, const char *__delim)
strtok_P() parses the string s into tokens. The first call to strtok_P() should have s as its first argument. Subsequent calls should have the first argument set to NULL. If a token ends with a delimiter, this delimiting character is overwritten with a '\0' and a pointer to the next character is saved for the next call to strtok_P(). The delimiter string delim may be different for each call.
The strtok_P() function is similar to strtok() except that delim is pointer to a string in program space.
The strtok_P() function returns a pointer to the next token or NULL when no more tokens are found.
strtok_P() is NOT reentrant. For a reentrant version of this function see strtok_rP().