bidi.c: update the API.

The input length field is now a size_t rather than an int, on general
principles. The return value is now void (we weren't using the
previous return value at all). And we now require the client to have
previously allocated a BidiContext, which will allow allocated storage
to be reused between runs, saving a lot of churn on malloc.

(However, the current BidiContext doesn't contain anything
interesting. I could have moved the existing mallocs into it, but
there's no point, since I'm about to rewrite the whole thing anyway.)

defs.h

@@ -170,6 +170,8 @@ typedef struct SessionSpecial SessionSpecial;
 
 typedef struct StripCtrlChars StripCtrlChars;
 
+typedef struct BidiContext BidiContext;
+
 /*
  * A small structure wrapping up a (pointer, length) pair so that it
  * can be conveniently passed to or from a function.

putty.h

@@ -2359,7 +2359,9 @@ typedef struct bidi_char {
     unsigned int origwc, wc;
     unsigned short index, nchars;
 } bidi_char;
-int do_bidi(bidi_char *line, int count);
+BidiContext *bidi_new_context(void);
+void bidi_free_context(BidiContext *ctx);
+void do_bidi(BidiContext *ctx, bidi_char *line, size_t count);
 int do_shape(bidi_char *line, bidi_char *to, int count);
 bool is_rtl(int c);
 

terminal/bidi.c

@@ -1116,6 +1116,22 @@ int do_shape(bidi_char *line, bidi_char *to, int count)
     return 1;
 }
 
+struct BidiContext {
+    int dummy;
+};
+
+BidiContext *bidi_new_context(void)
+{
+    BidiContext *ctx = snew(BidiContext);
+    memset(ctx, 0, sizeof(BidiContext));
+    return ctx;
+}
+
+void bidi_free_context(BidiContext *ctx)
+{
+    sfree(ctx);
+}
+
 /*
  * The Main Bidi Function, and the only function that should
  * be used by the outside world.
@@ -1124,7 +1140,7 @@ int do_shape(bidi_char *line, bidi_char *to, int count)
  * the Bidirectional algorithm to.
  */
 
-int do_bidi(bidi_char *line, int count)
+void do_bidi(BidiContext *ctx, bidi_char *line, size_t count)
 {
     unsigned char* types;
     unsigned char* levels;
@@ -1145,7 +1161,7 @@ int do_bidi(bidi_char *line, int count)
         }
     }
     if (!yes)
-        return L;
+        return;
 
     /* Initialize types, levels */
     types = snewn(count, unsigned char);
@@ -1565,7 +1581,7 @@ int do_bidi(bidi_char *line, int count)
      */
     sfree(types);
     sfree(levels);
-    return R;
+    return;
 }
 
 

terminal/terminal.c

@@ -2048,6 +2048,8 @@ Terminal *term_init(Conf *myconf, struct unicode_data *ucsdata, TermWin *win)
     term->win_scrollbar_update_pending = false;
     term->win_palette_pending = false;
 
+    term->bidi_ctx = bidi_new_context();
+
     palette_reset(term, false);
 
     return term;
@@ -2107,6 +2109,8 @@ void term_free(Terminal *term)
     sfree(term->window_title);
     sfree(term->icon_title);
 
+    bidi_free_context(term->bidi_ctx);
+
     sfree(term);
 }
 
@@ -5662,7 +5666,7 @@ static termchar *term_bidi_line(Terminal *term, struct termline *ldata,
             }
 
             if(!term->no_bidi)
-                do_bidi(term->wcFrom, nbc);
+                do_bidi(term->bidi_ctx, term->wcFrom, nbc);
 
             if(!term->no_arabicshaping) {
                 do_shape(term->wcFrom, term->wcTo, nbc);

terminal/terminal.h

@@ -353,6 +353,8 @@ struct terminal_tag {
     char *window_title, *icon_title;
     bool minimised;
 
+    BidiContext *bidi_ctx;
+
     /* Multi-layered colour palette. The colours from Conf (plus the
      * default xterm-256 ones that don't have Conf ids at all) have
      * lowest priority, followed by platform overrides if any,