Merge "Everyone has CLZ."
diff --git a/libc/arch-arm/bionic/ffs.S b/libc/arch-arm/bionic/ffs.S
index c59091f..701af8c 100644
--- a/libc/arch-arm/bionic/ffs.S
+++ b/libc/arch-arm/bionic/ffs.S
@@ -31,55 +31,11 @@
#include <machine/asm.h>
#include <machine/cpu-features.h>
-/*
- * ffs - find first set bit, this algorithm isolates the first set
- * bit, then multiplies the number by 0x0450fbaf which leaves the top
- * 6 bits as an index into the table. This algorithm should be a win
- * over the checking each bit in turn as per the C compiled version.
- *
- * Some newer ARM architectures have an instruction named
- * CLZ (count leading Zero's) that is used
- *
- * This is the ffs algorithm devised by d.seal and posted to comp.sys.arm on
- * 16 Feb 1994.
- */
-
ENTRY(ffs)
/* Standard trick to isolate bottom bit in r0 or 0 if r0 = 0 on entry */
rsb r1, r0, #0
ands r0, r0, r1
-#ifndef __ARM_HAVE_CLZ
- /*
- * now r0 has at most one set bit, call this X
- * if X = 0, all further instructions are skipped
- */
- adrne r2, .L_ffs_table
- orrne r0, r0, r0, lsl #4 /* r0 = X * 0x11 */
- orrne r0, r0, r0, lsl #6 /* r0 = X * 0x451 */
- rsbne r0, r0, r0, lsl #16 /* r0 = X * 0x0450fbaf */
-
- /* now lookup in table indexed on top 6 bits of r0 */
- ldrneb r0, [ r2, r0, lsr #26 ]
-
- bx lr
-END(ffs)
-
-.text;
-.type .L_ffs_table, _ASM_TYPE_OBJECT;
-.L_ffs_table:
-/* 0 1 2 3 4 5 6 7 */
- .byte 0, 1, 2, 13, 3, 7, 0, 14 /* 0- 7 */
- .byte 4, 0, 8, 0, 0, 0, 0, 15 /* 8-15 */
- .byte 11, 5, 0, 0, 9, 0, 0, 26 /* 16-23 */
- .byte 0, 0, 0, 0, 0, 22, 28, 16 /* 24-31 */
- .byte 32, 12, 6, 0, 0, 0, 0, 0 /* 32-39 */
- .byte 10, 0, 0, 25, 0, 0, 21, 27 /* 40-47 */
- .byte 31, 0, 0, 0, 0, 24, 0, 20 /* 48-55 */
- .byte 30, 0, 23, 19, 29, 18, 17, 0 /* 56-63 */
-#else /* !defined(__ARM_HAVE_CLZ) */
clzne r0, r0
rsbne r0, r0, #32
bx lr
END(ffs)
-#endif /* !defined(__ARM_HAVE_CLZ) */
-
diff --git a/tests/Android.mk b/tests/Android.mk
index eb97e6c..da9d676 100644
--- a/tests/Android.mk
+++ b/tests/Android.mk
@@ -71,6 +71,7 @@
stdio_test.cpp \
stdlib_test.cpp \
string_test.cpp \
+ strings_test.cpp \
stubs_test.cpp \
unistd_test.cpp \
diff --git a/tests/strings_test.cpp b/tests/strings_test.cpp
new file mode 100644
index 0000000..5200859
--- /dev/null
+++ b/tests/strings_test.cpp
@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <gtest/gtest.h>
+
+#include <errno.h>
+#include <strings.h>
+
+TEST(strings, ffs) {
+ ASSERT_EQ( 0, ffs(0x00000000));
+ ASSERT_EQ( 1, ffs(0x00000001));
+ ASSERT_EQ( 6, ffs(0x00000020));
+ ASSERT_EQ(11, ffs(0x00000400));
+ ASSERT_EQ(16, ffs(0x00008000));
+ ASSERT_EQ(17, ffs(0x00010000));
+ ASSERT_EQ(22, ffs(0x00200000));
+ ASSERT_EQ(27, ffs(0x04000000));
+ ASSERT_EQ(32, ffs(0x80000000));
+}