(decode_coding_utf_8): Add simple loop for fast processing of ASCII characters.

1 files changed, 39 insertions, 0 deletions

diff --git a/src/coding.c b/src/coding.c
index e779197bbde..385a22a188d 100644
--- a/src/coding.c
+++ b/src/coding.c
@@ -1363,6 +1363,45 @@ decode_coding_utf_8 (struct coding_system *coding)
           break;
         }
 
+      /* In the simple case, rapidly handle ordinary characters */
+      if (multibytep && ! eol_dos
+          && charbuf < charbuf_end - 6 && src < src_end - 6)
+        {
+          while (charbuf < charbuf_end - 6 && src < src_end - 6)
+            {
+              c1 = *src;
+              if (c1 & 0x80)
+                break;
+              src++;
+              consumed_chars++;
+              *charbuf++ = c1;
+
+              c1 = *src;
+              if (c1 & 0x80)
+                break;
+              src++;
+              consumed_chars++;
+              *charbuf++ = c1;
+
+              c1 = *src;
+              if (c1 & 0x80)
+                break;
+              src++;
+              consumed_chars++;
+              *charbuf++ = c1;
+
+              c1 = *src;
+              if (c1 & 0x80)
+                break;
+              src++;
+              consumed_chars++;
+              *charbuf++ = c1;
+            }
+          /* If we handled at least one character, restart the main loop.  */
+          if (src != src_base)
+            continue;
+        }
+
       if (byte_after_cr >= 0)
         c1 = byte_after_cr, byte_after_cr = -1;
       else