Merge pull request #60 from masatake/more-inline

Make one more function inine and use a table instead of switch/case

Author: masatake

NEWS.md

@@ -1,21 +1,21 @@
 # Version XXX
 
-- imporve performance; put inline keyword on a hot spot function.
+- improve performance; put inline keyword on hot spot functions.
 
-	- before this change
+	- before this change (0.4.0)
 
 		```
-		$ /bin/time ./readtags -t ~/.citre/kernel82.tags -l > /dev/null
-		9.59user 0.42system 0:10.06elapsed 99%CPU (0avgtext+0avgdata 2819340maxresident)k
-		0inputs+0outputs (0major+44149minor)pagefaults 0swaps
+		$ /bin/time ~/bin/readtags -t ~/.citre/kernel82.tags -l > /dev/null
+		7.68user 0.15system 0:07.88elapsed 99%CPU (0avgtext+0avgdata 2819592maxresident)k
+		0inputs+0outputs (0major+44138minor)pagefaults 0swaps
 		```
 
 	- after this change
 
 		```
-		$ /bin/time ./readtags -t ~/.citre/kernel82.tags -l > /dev/null
-		7.82user 0.43system 0:08.30elapsed 99%CPU (0avgtext+0avgdata 2819688maxresident)k
-		0inputs+0outputs (0major+44138minor)pagefaults 0swaps
+		$ /bin/time ~/bin/readtags -t ~/.citre/kernel82.tags -l > /dev/null
+		4.67user 0.19system 0:04.89elapsed 99%CPU (0avgtext+0avgdata 2819612maxresident)k
+		0inputs+0outputs (0major+44137minor)pagefaults 0swaps
 		```
 
 # Version 0.4.0

readtags.c

@@ -156,10 +156,22 @@ static int xdigitValue (unsigned char digit)
 		return 0;
 }
 
+static unsigned char altchars[0x100] = {
+	['\\'] = '\\',
+	['a']  = '\a', /* u-ctags extension */
+	['b']  = '\b', /* u-ctags extension */
+	['f']  = '\f', /* u-ctags extension */
+	['n']  = '\n',
+	['r']  = '\r',
+	['t']  = '\t',
+	['v']  = '\v', /* u-ctags extension */
+};
+
 /*
  * Reads the first character from the string, possibly un-escaping it, and
  * advances *s to the start of the next character.
  */
+
 READTAGS_INLINE
 int readTagCharacter (const char **const s)
 {
@@ -170,28 +182,27 @@ int readTagCharacter (const char **const s)
 
 	if (c == '\\')
 	{
+		unsigned char a;
 		switch (*p)
 		{
-			case 't': c = '\t'; p++; break;
-			case 'r': c = '\r'; p++; break;
-			case 'n': c = '\n'; p++; break;
-			case '\\': c = '\\'; p++; break;
-			/* Universal-CTags extensions */
-			case 'a': c = '\a'; p++; break;
-			case 'b': c = '\b'; p++; break;
-			case 'v': c = '\v'; p++; break;
-			case 'f': c = '\f'; p++; break;
-			case 'x':
-				if (isxdigit (p[1]) && isxdigit (p[2]))
+		default:
+			a = altchars[*p];
+			if (a) {
+				c = a;
+				p++;
+			}
+			break;
+		case 'x':
+			if (isxdigit (p[1]) && isxdigit (p[2]))
+			{
+				int val = (xdigitValue (p[1]) << 4) | xdigitValue (p[2]);
+				if (val < 0x80)
 				{
-					int val = (xdigitValue (p[1]) << 4) | xdigitValue (p[2]);
-					if (val < 0x80)
-					{
-						p += 3;
-						c = val;
-					}
+					p += 3;
+					c = val;
 				}
-				break;
+			}
+			break;
 		}
 	}
 
@@ -541,7 +552,8 @@ static unsigned int countContinuousBackslashesBackward(const char *from,
  * It is converted to 0x9 and occupies one byte.
  * memmove called here for shortening the line
  * buffer. */
-static char *unescapeInPlace (char *q, char **tab, size_t *p_len)
+READTAGS_INLINE
+char *unescapeInPlace (char *q, char **tab, size_t *p_len)
 {
 	char *p = q;