From 9d1008c523a56e27c0f568de1a63a649d01a006e Mon Sep 17 00:00:00 2001
From: Pavol Babincak <scroolik@gmail.com>
Date: Mon, 1 May 2006 22:58:51 +0200
Subject: [PATCH] Added utf8_prevchar for moving throught UTF-8 string to left.

---
 src/intl/charsets.c | 18 ++++++++++++++++++
 src/intl/charsets.h |  1 +
 2 files changed, 19 insertions(+)

diff --git a/src/intl/charsets.c b/src/intl/charsets.c
index 52c9dfd04..35c6ce8d3 100644
--- a/src/intl/charsets.c
+++ b/src/intl/charsets.c
@@ -252,6 +252,24 @@ strlen_utf8(unsigned char **str)
 	return x;
 }
 
+#define utf8_issingle(p) (((p) & 0x80) == 0)
+#define utf8_islead(p) (utf8_issingle(p) || ((p) & 0xc0) == 0xc0)
+
+/* Start from @current and move back to @pos char. This pointer return. The
+ * most left pointer is @start. */
+inline unsigned char *
+utf8_prevchar(unsigned char *current, int pos, unsigned char *start)
+{
+  if (current == NULL || start == NULL || pos < 0)
+    return NULL;
+  while (pos > 0 && current != start) {
+    current--;
+    if (utf8_islead(*current))
+      pos--;
+  }
+  return current;
+}
+
 /* Count number of standard terminal cells needed for displaying UTF-8
  * character. */
 int
diff --git a/src/intl/charsets.h b/src/intl/charsets.h
index 2b5380b3f..04e6a0f68 100644
--- a/src/intl/charsets.h
+++ b/src/intl/charsets.h
@@ -55,6 +55,7 @@ int is_cp_special(int);
 void free_conv_table(void);
 #ifdef CONFIG_UTF_8
 inline unsigned char *encode_utf_8(unicode_val_T);
+inline unsigned char *utf8_prevchar(unsigned char *, int, unsigned char *);
 inline int utf8charlen(const unsigned char *);
 int utf8_char2cells(unsigned char *, unsigned char *);
 int utf8_ptr2cells(unsigned char *, unsigned char *);