diff options
| author | Corinna Vinschen <corinna@vinschen.de> | 2012-11-30 13:31:38 +0400 |
|---|---|---|
| committer | Corinna Vinschen <corinna@vinschen.de> | 2012-11-30 13:31:38 +0400 |
| commit | b8637f43b08b1407cde47fc0477a1100b617f71f (patch) | |
| tree | 357fd0f56dcc9e9b6bb050ef7240642d1d587d7e /newlib/libc/machine | |
| parent | d551cb9226153a6855bde55aa8f0a7b0b8e688ab (diff) | |
* libc/machine/arm/strcmp.S (compute_return_value): Fix return value.
* testsuite/newlib.string/strcmp-1.c (main): Add new test cases.
Diffstat (limited to 'newlib/libc/machine')
| -rw-r--r-- | newlib/libc/machine/arm/strcmp.S | 12 |
1 files changed, 11 insertions, 1 deletions
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 |