Simple coldfire assembly strlen() function, 20-25% faster than the c

version. Move function out of iram as it turns out that makes it 
slightly faster.


git-svn-id: svn://svn.rockbox.org/rockbox/trunk@13713 a1c6a512-1295-4272-9138-f99709370657

1 files changed, 40 insertions, 0 deletions

diff --git a/firmware/target/coldfire/strlen-coldfire.S b/firmware/target/coldfire/strlen-coldfire.S
new file mode 100644
index 0000000000..9be42a5864
--- /dev/null
+++ b/firmware/target/coldfire/strlen-coldfire.S
@@ -0,0 +1,40 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ * $Id $
+ *
+ * Copyright (C) 2007 Nils Wallménius
+ *
+ * All files in this archive are subject to the GNU General Public License.
+ * See the file COPYING in the source tree root for full license agreement.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ****************************************************************************/
+
+/* size_t strlen(const char *str) */
+
+    .section    .text,"ax",@progbits
+    .align  2
+    .globl  strlen
+    .type   strlen, @function
+
+strlen:
+    move.l 4(%sp),%a0    /* %a0 = *str */
+    move.l %a0,%d0       /* %d0 = start address */
+
+    1:
+    tst.b (%a0)+         /* test if %a0 == 0 and increment */
+    bne.b 1b             /* if the test was false repeat */
+
+    sub.l %d0,%a0        /* how many times did we repeat? */
+    move.l %a0,%d0
+    subq.l #1,%d0        /* %d0 is 1 too large due to the last increment */
+    rts
+    .size   strlen, .-strlen
+