From ed492ba62440cdfced0a12e35415d701988a77b7 Mon Sep 17 00:00:00 2001
From: simonmar <unknown>
Date: Tue, 21 Oct 2003 13:24:31 +0000
Subject: [PATCH] [project @ 2003-10-21 13:24:31 by simonmar] Make the GHC
 implementation of peekCString run in constant stack-space
 by checking the length of the array first and then working
 backwards from the end.  Interestingly, this version is
 faster than the original.

---
 Foreign/C/String.hs |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/Foreign/C/String.hs b/Foreign/C/String.hs
index d2d2a29..49d5a2d 100644
--- a/Foreign/C/String.hs
+++ b/Foreign/C/String.hs
@@ -86,14 +86,14 @@ peekCString    :: CString -> IO String
 #ifndef __GLASGOW_HASKELL__
 peekCString cp  = do cs <- peekArray0 nUL cp; return (cCharsToChars cs)
 #else
-peekCString cp = loop 0
+peekCString cp = do
+  l <- lengthArray0 nUL cp
+  if l <= 0 then return "" else loop "" (l-1)
   where
-    loop i = do
+    loop s i = do
         xval <- peekElemOff cp i
 	let val = castCCharToChar xval
-        if (val `seq` (xval == nUL)) then return [] else do
-            rest <- loop (i+1)
-            return (val : rest)
+	val `seq` if i <= 0 then return (val:s) else loop (val:s) (i-1)
 #endif
 
 -- marshal a C string with explicit length into a Haskell string 
-- 
1.7.10.4