1 files changed, 101 insertions, 0 deletions

diff --git a/src/buffer.h b/src/buffer.h
index 9875b8a447b..3da49414bb8 100644
--- a/src/buffer.h
+++ b/src/buffer.h
@@ -1562,6 +1562,107 @@ CHARACTER_WIDTH (int c)
           : !NILP (BVAR (current_buffer, ctl_arrow)) ? 2 : 4);
 }
 
+
+/* Like fetch_string_char_advance, but fetch character from the current
+   buffer.  */
+
+INLINE int
+fetch_char_advance (ptrdiff_t *charidx, ptrdiff_t *byteidx)
+{
+  int output;
+  ptrdiff_t c = *charidx, b = *byteidx;
+  c++;
+  unsigned char *chp = BYTE_POS_ADDR (b);
+  if (!NILP (BVAR (current_buffer, enable_multibyte_characters)))
+    {
+      int chlen;
+      output = string_char_and_length (chp, &chlen);
+      b += chlen;
+    }
+  else
+    {
+      output = *chp;
+      b++;
+    }
+  *charidx = c;
+  *byteidx = b;
+  return output;
+}
+
+
+/* Like fetch_char_advance, but assumes the current buffer is multibyte.  */
+
+INLINE int
+fetch_char_advance_no_check (ptrdiff_t *charidx, ptrdiff_t *byteidx)
+{
+  int output;
+  ptrdiff_t c = *charidx, b = *byteidx;
+  c++;
+  unsigned char *chp = BYTE_POS_ADDR (b);
+  int chlen;
+  output = string_char_and_length (chp, &chlen);
+  b += chlen;
+  *charidx = c;
+  *byteidx = b;
+  return output;
+}
+
+/* Return the number of bytes in the multibyte character in BUF
+   that starts at position POS_BYTE.  This relies on the fact that
+   *GPT_ADDR and *Z_ADDR are always accessible and the values are
+   '\0'.  No range checking of POS_BYTE.  */
+
+INLINE int
+buf_next_char_len (struct buffer *buf, ptrdiff_t pos_byte)
+{
+  unsigned char *chp = BUF_BYTE_ADDRESS (buf, pos_byte);
+  return BYTES_BY_CHAR_HEAD (*chp);
+}
+
+INLINE int
+next_char_len (ptrdiff_t pos_byte)
+{
+  return buf_next_char_len (current_buffer, pos_byte);
+}
+
+/* Return the number of bytes in the multibyte character in BUF just
+   before POS_BYTE.  No range checking of POS_BYTE.  */
+
+INLINE int
+buf_prev_char_len (struct buffer *buf, ptrdiff_t pos_byte)
+{
+  unsigned char *chp
+    = (BUF_BEG_ADDR (buf) + pos_byte - BEG_BYTE
+       + (pos_byte <= BUF_GPT_BYTE (buf) ? 0 : BUF_GAP_SIZE (buf)));
+  return raw_prev_char_len (chp);
+}
+
+INLINE int
+prev_char_len (ptrdiff_t pos_byte)
+{
+  return buf_prev_char_len (current_buffer, pos_byte);
+}
+
+/* Increment both *CHARPOS and *BYTEPOS, each in the appropriate way.  */
+
+INLINE void
+inc_both (ptrdiff_t *charpos, ptrdiff_t *bytepos)
+{
+  (*charpos)++;
+  (*bytepos) += (!NILP (BVAR (current_buffer, enable_multibyte_characters))
+                 ? next_char_len (*bytepos) : 1);
+}
+
+/* Decrement both *CHARPOS and *BYTEPOS, each in the appropriate way.  */
+
+INLINE void
+dec_both (ptrdiff_t *charpos, ptrdiff_t *bytepos)
+{
+  (*charpos)--;
+  (*bytepos) -= (!NILP (BVAR (current_buffer, enable_multibyte_characters))
+                 ? prev_char_len (*bytepos) : 1);
+}
+
 INLINE_HEADER_END
 
 #endif /* EMACS_BUFFER_H */