+ * Diagnostic function: verify that a termline has a correct
+ * combining character structure.
+ *
+ * XXX-REMOVE-BEFORE-RELEASE: This is a performance-intensive
+ * check. Although it's currently really useful for getting all the
+ * bugs out of the new cc stuff, it will want to be absent when we
+ * make a proper release.
+ */
+static void cc_check(termline *line)
+{
+ unsigned char *flags;
+ int i, j;
+
+ assert(line->size >= line->cols);
+
+ flags = snewn(line->size, unsigned char);
+
+ for (i = 0; i < line->size; i++)
+ flags[i] = (i < line->cols);
+
+ for (i = 0; i < line->cols; i++) {
+ j = i;
+ while (line->chars[j].cc_next) {
+ j += line->chars[j].cc_next;
+ assert(j >= line->cols && j < line->size);
+ assert(!flags[j]);
+ flags[j] = TRUE;
+ }
+ }
+
+ j = line->cc_free;
+ if (j) {
+ while (1) {
+ assert(j >= line->cols && j < line->size);
+ assert(!flags[j]);
+ flags[j] = TRUE;
+ if (line->chars[j].cc_next)
+ j += line->chars[j].cc_next;
+ else
+ break;
+ }
+ }
+
+ j = 0;
+ for (i = 0; i < line->size; i++)
+ j += (flags[i] != 0);
+
+ assert(j == line->size);
+
+ sfree(flags);
+}
+
+/*
+ * Add a combining character to a character cell.
+ */
+static void add_cc(termline *line, int col, unsigned long chr)
+{
+ int newcc;
+
+ assert(col >= 0 && col < line->cols);
+
+ /*
+ * Start by extending the cols array if the free list is empty.
+ */
+ if (!line->cc_free) {
+ int n = line->size;
+ line->size += 16 + (line->size - line->cols) / 2;
+ line->chars = sresize(line->chars, line->size, termchar);
+ line->cc_free = n;
+ while (n < line->size) {
+ if (n+1 < line->size)
+ line->chars[n].cc_next = 1;
+ else
+ line->chars[n].cc_next = 0;
+ n++;
+ }
+ }
+
+ /*
+ * Now walk the cc list of the cell in question.
+ */
+ while (line->chars[col].cc_next)
+ col += line->chars[col].cc_next;
+
+ /*
+ * `col' now points at the last cc currently in this cell; so
+ * we simply add another one.
+ */
+ newcc = line->cc_free;
+ if (line->chars[newcc].cc_next)
+ line->cc_free = newcc + line->chars[newcc].cc_next;
+ else
+ line->cc_free = 0;
+ line->chars[newcc].cc_next = 0;
+ line->chars[newcc].chr = chr;
+ line->chars[col].cc_next = newcc - col;
+
+ cc_check(line); /* XXX-REMOVE-BEFORE-RELEASE */
+}
+
+/*
+ * Clear the combining character list in a character cell.
+ */
+static void clear_cc(termline *line, int col)
+{
+ int oldfree, origcol = col;
+
+ assert(col >= 0 && col < line->cols);
+
+ if (!line->chars[col].cc_next)
+ return; /* nothing needs doing */
+
+ oldfree = line->cc_free;
+ line->cc_free = col + line->chars[col].cc_next;
+ while (line->chars[col].cc_next)
+ col += line->chars[col].cc_next;
+ if (oldfree)
+ line->chars[col].cc_next = oldfree - col;
+ else
+ line->chars[col].cc_next = 0;
+
+ line->chars[origcol].cc_next = 0;
+
+ cc_check(line); /* XXX-REMOVE-BEFORE-RELEASE */
+}
+
+/*
+ * Compare two character cells for equality. Special case required
+ * in do_paint() where we override what we expect the chr and attr
+ * fields to be.
+ */
+static int termchars_equal_override(termchar *a, termchar *b,
+ unsigned long bchr, unsigned long battr)
+{
+ /* FULL-TERMCHAR */
+ if (a->chr != bchr)
+ return FALSE;
+ if ((a->attr &~ DATTR_MASK) != (battr &~ DATTR_MASK))
+ return FALSE;
+ while (a->cc_next || b->cc_next) {
+ if (!a->cc_next || !b->cc_next)
+ return FALSE; /* one cc-list ends, other does not */
+ a += a->cc_next;
+ b += b->cc_next;
+ if (a->chr != b->chr)
+ return FALSE;
+ }
+ return TRUE;
+}
+
+static int termchars_equal(termchar *a, termchar *b)
+{
+ return termchars_equal_override(a, b, b->chr, b->attr);
+}
+
+/*
+ * Copy a character cell. (Requires a pointer to the destination
+ * termline, so as to access its free list.)
+ */
+static void copy_termchar(termline *destline, int x, termchar *src)
+{
+ clear_cc(destline, x);
+
+ destline->chars[x] = *src; /* copy everything except cc-list */
+ destline->chars[x].cc_next = 0; /* and make sure this is zero */
+
+ while (src->cc_next) {
+ src += src->cc_next;
+ add_cc(destline, x, src->chr);
+ }
+
+ cc_check(destline); /* XXX-REMOVE-BEFORE-RELEASE */
+}
+
+/*
+ * Move a character cell within its termline.
+ */
+static void move_termchar(termline *line, termchar *dest, termchar *src)
+{
+ /* First clear the cc list from the original char, just in case. */
+ clear_cc(line, dest - line->chars);
+
+ /* Move the character cell and adjust its cc_next. */
+ *dest = *src; /* copy everything except cc-list */
+ if (src->cc_next)
+ dest->cc_next = src->cc_next - (dest-src);
+
+ /* Ensure the original cell doesn't have a cc list. */
+ src->cc_next = 0;
+
+ cc_check(line); /* XXX-REMOVE-BEFORE-RELEASE */
+}
+
+/*