From 685e54f4dd7e8387f6fba3c691063021303ffe19 Mon Sep 17 00:00:00 2001
From: Zdenek Kabelac <zkabelac@redhat.com>
Date: Thu, 10 Mar 2011 14:51:35 +0000
Subject: [PATCH] Optimise _eat_space and _get_token

Makes the code more readable and has a smaller number of memory
accesses thus it's small optimisation as well.

For _get_token() optimize number parsing. Check for '.' char only
if it's not a digit. Move pointer incrementation into one place.

For _eat_space() check only p->te for '\0' in skipping of comment line.
Avoid check for '\0' when we know it is space. Also master while loop
doesn't need checking p->tb for '\0'. We just need to check p->tb
isn't already at the end of buffer. This could give 'extra' loop cycle
if we are already there - but safes memory access in every other case.
---
 WHATS_NEW           |  1 +
 lib/config/config.c | 42 +++++++++++++++++++++---------------------
 2 files changed, 22 insertions(+), 21 deletions(-)

diff --git a/WHATS_NEW b/WHATS_NEW
index d60f22668..42d74914b 100644
--- a/WHATS_NEW
+++ b/WHATS_NEW
@@ -1,5 +1,6 @@
 Version 2.02.85 - 
 ===================================
+  Optimise _get_token() and _eat_space().
   Add _lv_postorder_vg() to improve efficiency for all LVs in VG.
   Use hash tables to speedup string search in validate_vg().
   Refactor allocation of VG structure, add alloc_vg().
diff --git a/lib/config/config.c b/lib/config/config.c
index e6e97cfe2..9fb2bf61d 100644
--- a/lib/config/config.c
+++ b/lib/config/config.c
@@ -822,18 +822,20 @@ static void _get_token(struct parser *p, int tok_prev)
 	case '+':
 	case '-':
 		if (values_allowed) {
-			te++;
-			while ((te != p->fe) && (*te)) {
-				if (*te == '.') {
-					if (p->t == TOK_FLOAT)
-						break;
-					p->t = TOK_FLOAT;
-				} else if (!isdigit((int) *te))
+			while (++te != p->fe) {
+				if (!isdigit((int) *te)) {
+					if (*te == '.') {
+						if (p->t != TOK_FLOAT) {
+							p->t = TOK_FLOAT;
+							continue;
+						}
+					}
 					break;
-				te++;
+				}
 			}
 			break;
 		}
+		/* fall through */
 
 	default:
 		p->t = TOK_IDENTIFIER;
@@ -850,21 +852,19 @@ static void _get_token(struct parser *p, int tok_prev)
 
 static void _eat_space(struct parser *p)
 {
-	while ((p->tb != p->fe) && (*p->tb)) {
+	while (p->tb != p->fe) {
 		if (*p->te == '#')
-			while ((p->te != p->fe) && (*p->te) && (*p->te != '\n'))
-				p->te++;
-
-		else if (isspace(*p->te)) {
-			while ((p->te != p->fe) && (*p->te) && isspace(*p->te)) {
-				if (*p->te == '\n')
-					p->line++;
-				p->te++;
-			}
-		}
+			while ((p->te != p->fe) && (*p->te != '\n') && (*p->te))
+				++p->te;
 
-		else
-			return;
+		else if (!isspace(*p->te))
+			break;
+
+		while ((p->te != p->fe) && isspace(*p->te)) {
+			if (*p->te == '\n')
+				++p->line;
+			++p->te;
+		}
 
 		p->tb = p->te;
 	}
-- 
2.43.5