6 files changed, 50 insertions, 7 deletions

diff --git a/engines/glk/frotz/glk_interface.h b/engines/glk/frotz/glk_interface.h
index 0103f88b1b..5e2fa62663 100644
--- a/engines/glk/frotz/glk_interface.h
+++ b/engines/glk/frotz/glk_interface.h
@@ -94,10 +94,33 @@ public:
 	bool _soundLocked;
 	bool _soundPlaying;
 protected:
+	/**
+	 * Return the length of the character in screen units.
+	 */
 	int os_char_width(zchar z);
+
+	/**
+	 * Calculate the length of a word in screen units. Apart from letters,
+	 * the word may contain special codes:
+	 *
+	 *    ZC_NEW_STYLE - next character is a new text style
+	 *    ZC_NEW_FONT  - next character is a new font
+	 */
 	int os_string_width(const zchar *s);
+
+	/**
+	 * Return the length of a string
+	 */
 	int os_string_length(zchar *s);
+
+	/**
+	 * Prepare a sample for playing
+	 */
 	void os_prepare_sample(int a);
+
+	/**
+	 * Signal that a given sample is finished with
+	 */
 	void os_finish_with_sample(int a);
 
 	/**
diff --git a/engines/glk/frotz/mem.cpp b/engines/glk/frotz/mem.cpp
index 378e49666d..6ee6781690 100644
--- a/engines/glk/frotz/mem.cpp
+++ b/engines/glk/frotz/mem.cpp
@@ -174,10 +174,10 @@ void Mem::initializeStoryFile() {
 }
 
 void Mem::initializeUndo() {
-	void *reserved = nullptr;
+	byte *reserved = nullptr;
 
 	if (reserve_mem != 0) {
-		if ((reserved = malloc(reserve_mem)) == NULL)
+		if ((reserved = new byte[reserve_mem]) == nullptr)
 			return;
 	}
 
diff --git a/engines/glk/frotz/processor.h b/engines/glk/frotz/processor.h
index 7c8944f451..5f61a2e658 100644
--- a/engines/glk/frotz/processor.h
+++ b/engines/glk/frotz/processor.h
@@ -314,11 +314,32 @@ private:
 	 * @{
 	 */
 
+	/**
+	 * Start printing a so-called debugging message. The contents of the
+	 * message are passed to the message stream, a Frotz specific output
+	 * stream with maximum priority.
+	 */
+	void screen_mssg_on();
+
+	/**
+	 * Stop printing a "debugging" message
+	 */
+	void screen_mssg_off();
+
+	/**
+	 * Display a single character on the screen.
+	 */
 	void screen_char(zchar c);
+
+	/**
+	 * Print a newline to the screen.
+	 */
 	void screen_new_line();
+
+	/**
+	 * Print a newline to the screen.
+	 */
 	void screen_word(const zchar *s);
-	void screen_mssg_on();
-	void screen_mssg_off();
 
 	/**@}*/
 
diff --git a/engines/glk/frotz/processor_buffer.cpp b/engines/glk/frotz/processor_buffer.cpp
index c4eaeaa42e..b8b37ed60e 100644
--- a/engines/glk/frotz/processor_buffer.cpp
+++ b/engines/glk/frotz/processor_buffer.cpp
@@ -158,7 +158,7 @@ void Processor::runtimeError(ErrorCode errNum) {
 	if (_err_report_mode == ERR_REPORT_FATAL
 		|| (!_ignore_errors && errNum <= ERR_MAX_FATAL)) {
 		flush_buffer();
-		error(ERR_MESSAGES[errNum - 1]);
+		error("%s", ERR_MESSAGES[errNum - 1]);
 		return;
 	}
 
diff --git a/engines/glk/frotz/processor_screen.cpp b/engines/glk/frotz/processor_screen.cpp
index 2e07b477cb..c0d8ca1e2a 100644
--- a/engines/glk/frotz/processor_screen.cpp
+++ b/engines/glk/frotz/processor_screen.cpp
@@ -122,7 +122,6 @@ void Processor::screen_word(const zchar *s) {
 	}
 }
 
-
 void Processor::z_buffer_mode() {
 	// No implementation
 }
diff --git a/engines/glk/frotz/processor_streams.cpp b/engines/glk/frotz/processor_streams.cpp
index 93b9c0bb91..ebeb3035f7 100644
--- a/engines/glk/frotz/processor_streams.cpp
+++ b/engines/glk/frotz/processor_streams.cpp
@@ -174,7 +174,7 @@ zchar Processor::stream_read_input(int max, zchar *buf, zword timeout, zword rou
 
     // Remove initial input from the transscript file or from the screen
     if (ostream_script && enable_scripting && !no_scripting)
-	script_erase_input(buf);
+		script_erase_input(buf);
 
     // Read input line from current input stream
 continue_input: