tweaks: use mnemonic constants instead of TRUE and FALSE

And use these constants in another context too.

src/files.c

@@ -639,16 +639,16 @@ void switch_to_adjacent_buffer(bool to_next)
 #endif
 }
 
-/* Switch to the previous entry in the openfile filebuffer. */
+/* Switch to the previous entry in the list of open files. */
 void switch_to_prev_buffer(void)
 {
-    switch_to_adjacent_buffer(FALSE);
+    switch_to_adjacent_buffer(BACKWARD);
 }
 
-/* Switch to the next entry in the openfile filebuffer. */
+/* Switch to the next entry in the list of open files. */
 void switch_to_next_buffer(void)
 {
-    switch_to_adjacent_buffer(TRUE);
+    switch_to_adjacent_buffer(FORWARD);
 }
 
 /* Delete an entry from the circular list of open files, and switch to the

src/move.c

@@ -502,7 +502,7 @@ void do_up(bool scroll_only)
     set_proper_index_and_pww(&leftedge, target_column, FALSE);
 
     if (scroll_only)
-	edit_scroll(UPWARD, 1);
+	edit_scroll(BACKWARD, 1);
 
     edit_redraw(was_current, FLOWING);
 
@@ -526,7 +526,7 @@ void do_down(bool scroll_only)
     set_proper_index_and_pww(&leftedge, target_column, TRUE);
 
     if (scroll_only)
-	edit_scroll(DOWNWARD, 1);
+	edit_scroll(FORWARD, 1);
 
     edit_redraw(was_current, FLOWING);
 

src/nano.h

@@ -132,6 +132,9 @@
 #define DISABLE_WRAPJUSTIFY 1
 #endif
 
+#define BACKWARD FALSE
+#define FORWARD TRUE
+
 /* Enumeration types. */
 typedef enum {
     NIX_FILE, DOS_FILE, MAC_FILE
@@ -149,10 +152,6 @@ typedef enum {
     SOFTMARK, HARDMARK
 } mark_type;
 
-typedef enum {
-    UPWARD, DOWNWARD
-} scroll_dir;
-
 typedef enum {
     CENTERING, FLOWING, STATIONARY
 } update_type;

src/proto.h

@@ -663,7 +663,7 @@ bool line_needs_update(const size_t old_column, const size_t new_column);
 int go_back_chunks(int nrows, filestruct **line, size_t *leftedge);
 int go_forward_chunks(int nrows, filestruct **line, size_t *leftedge);
 bool less_than_a_screenful(size_t was_lineno, size_t was_leftedge);
-void edit_scroll(scroll_dir direction, int nrows);
+void edit_scroll(bool direction, int nrows);
 #ifndef NANO_TINY
 size_t get_softwrap_breakpoint(const char *text, size_t leftedge,
 				bool *end_of_line);

src/winio.c

@@ -2902,7 +2902,7 @@ bool less_than_a_screenful(size_t was_lineno, size_t was_leftedge)
 
 /* Scroll the edit window in the given direction and the given number of rows,
  * and draw new lines on the blank lines left after the scrolling. */
-void edit_scroll(scroll_dir direction, int nrows)
+void edit_scroll(bool direction, int nrows)
 {
     filestruct *line;
     size_t leftedge;
@@ -2912,7 +2912,7 @@ void edit_scroll(scroll_dir direction, int nrows)
 
     /* Move the top line of the edit window the requested number of rows up or
      * down, and reduce the number of rows with the amount we couldn't move. */
-    if (direction == UPWARD)
+    if (direction == BACKWARD)
 	nrows -= go_back_chunks(nrows, &openfile->edittop, &openfile->firstcolumn);
     else
 	nrows -= go_forward_chunks(nrows, &openfile->edittop, &openfile->firstcolumn);
@@ -2935,7 +2935,7 @@ void edit_scroll(scroll_dir direction, int nrows)
 
     /* Scroll the text of the edit window a number of rows up or down. */
     scrollok(edit, TRUE);
-    wscrl(edit, (direction == UPWARD) ? -nrows : nrows);
+    wscrl(edit, (direction == BACKWARD) ? -nrows : nrows);
     scrollok(edit, FALSE);
 
     /* Part 2: nrows is now the number of rows in the scrolled region of the
@@ -2951,7 +2951,7 @@ void edit_scroll(scroll_dir direction, int nrows)
     leftedge = openfile->firstcolumn;
 
     /* If we scrolled forward, move down to the start of the blank region. */
-    if (direction == DOWNWARD)
+    if (direction == FORWARD)
 	go_forward_chunks(editwinrows - nrows, &line, &leftedge);
 
 #ifndef NANO_TINY