From b8637f43b08b1407cde47fc0477a1100b617f71f Mon Sep 17 00:00:00 2001
From: Corinna Vinschen <corinna@vinschen.de>
Date: Fri, 30 Nov 2012 09:31:38 +0000
Subject: 	* libc/machine/arm/strcmp.S (compute_return_value): Fix return
 value. 	* testsuite/newlib.string/strcmp-1.c (main): Add new test
 cases.

---
 newlib/libc/machine/arm/strcmp.S | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

(limited to 'newlib/libc/machine')

diff --git a/newlib/libc/machine/arm/strcmp.S b/newlib/libc/machine/arm/strcmp.S
index 6298bc98d..0a4057e3b 100644
--- a/newlib/libc/machine/arm/strcmp.S
+++ b/newlib/libc/machine/arm/strcmp.S
@@ -396,7 +396,17 @@ do_return:
         lsr     r2, r2, r0
 
 compute_return_value:
-        subs    r0, r1, r2
+        movs    r0, #1
+        cmp     r1, r2
+        /* The return value is computed as follows.
+        If r1>r2 then (C==1 and Z==0) and LS doesn't hold and r0 is #1 at return.
+        If r1<r2 then (C==0 and Z==0) and we execute SBC with carry_in=0,
+        which means r0:=r0-r0-1 and r0 is #-1 at return.
+        If r1=r2 then (C==1 and Z==1) and we execute SBC with carry_in=1,
+        which means r0:=r0-r0 and r0 is #0 at return.
+        (C==0 and Z==1) cannot happen because the carry bit is "not borrow".  */
+        it      ls
+        sbcls   r0, r0, r0
         bx      lr
 
 
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