4 files changed, 44 insertions, 46 deletions
diff --git a/payloads/libpayload/include/libpayload.h b/payloads/libpayload/include/libpayload.h
index 781a41d354..c3ca123f1f 100644
--- a/payloads/libpayload/include/libpayload.h
+++ b/payloads/libpayload/include/libpayload.h
@@ -311,6 +311,13 @@ u8 bin2hex(u8 b);
 u8 hex2bin(u8 h);
 void hexdump(const void *memory, size_t length);
 void fatal(const char *msg) __attribute__ ((noreturn));
+
+/* Count Leading Zeroes: clz(0) == 32, clz(0xf) == 28, clz(1 << 31) == 0 */
+static inline int clz(u32 x) { return x ? __builtin_clz(x) : sizeof(x) * 8; }
+/* Integer binary logarithm (rounding down): log2(0) == -1, log2(5) == 2 */
+static inline int log2(u32 x) { return sizeof(x) * 8 - clz(x) - 1; }
+/* Find First Set: __ffs(0xf) == 0, __ffs(0) == -1, __ffs(1 << 31) == 31 */
+static inline int __ffs(u32 x) { return log2(x & (u32)(-(s32)x)); }
 /** @} */
 
 
diff --git a/payloads/libpayload/include/strings.h b/payloads/libpayload/include/strings.h
deleted file mode 100644
index 5beddc6a7f..0000000000
--- a/payloads/libpayload/include/strings.h
+++ /dev/null
@@ -1,35 +0,0 @@
-/*
- * This file is part of the libpayload project.
- *
- * Copyright (C) 2011 secunet Security Networks AG
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- * 3. The name of the author may not be used to endorse or promote products
- *    derived from this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- */
-
-#ifndef _STRINGS_H
-#define _STRINGS_H
-
-int ffs(int i);
-
-#endif
diff --git a/payloads/libpayload/libc/Makefile.inc b/payloads/libpayload/libc/Makefile.inc
index b4f75a6cb5..272cda9ac4 100644
--- a/payloads/libpayload/libc/Makefile.inc
+++ b/payloads/libpayload/libc/Makefile.inc
@@ -29,10 +29,10 @@
 ##
 
 libc-$(CONFIG_LP_LIBC) += malloc.c printf.c console.c string.c
-libc-$(CONFIG_LP_LIBC) += memory.c ctype.c ipchecksum.c lib.c
+libc-$(CONFIG_LP_LIBC) += memory.c ctype.c ipchecksum.c lib.c libgcc.c
 libc-$(CONFIG_LP_LIBC) += rand.c time.c exec.c
 libc-$(CONFIG_LP_LIBC) += readline.c getopt_long.c sysinfo.c
-libc-$(CONFIG_LP_LIBC) += args.c strings.c
+libc-$(CONFIG_LP_LIBC) += args.c
 libc-$(CONFIG_LP_LIBC) += strlcpy.c
 libc-$(CONFIG_LP_LIBC) += qsort.c
 libc-$(CONFIG_LP_LIBC) += hexdump.c
diff --git a/payloads/libpayload/libc/strings.c b/payloads/libpayload/libc/libgcc.c
index 465ae4f12d..86698d8db3 100644
--- a/payloads/libpayload/libc/strings.c
+++ b/payloads/libpayload/libc/libgcc.c
@@ -1,7 +1,7 @@
 /*
  * This file is part of the libpayload project.
  *
- * Copyright (C) 2011 secunet Security Networks AG
+ * Copyright 2015 Google Inc.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -14,6 +14,10 @@
  * 3. The name of the author may not be used to endorse or promote products
  *    derived from this software without specific prior written permission.
  *
+ * Alternatively, this software may be distributed under the terms of the
+ * GNU General Public License ("GPL") version 2 as published by the Free
+ * Software Foundation.
+ *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
@@ -27,16 +31,38 @@
  * SUCH DAMAGE.
  */
 
-#include <strings.h>
+#include <libpayload.h>
 
-int ffs(int i)
+/*
+ * Provide platform-independent backend implementation for __builtin_clz() in
+ * <libpayload.h> in case GCC does not have an assembly version for this arch.
+ */
+
+int __clzsi2(u32 a);
+int __clzsi2(u32 a)
 {
-	int count = 1;
-	if (i == 0) return 0;
+	static const u8 four_bit_table[] = {
+		[0x0] = 4, [0x1] = 3, [0x2] = 2, [0x3] = 2,
+		[0x4] = 1, [0x5] = 1, [0x6] = 1, [0x7] = 1,
+		[0x8] = 0, [0x9] = 0, [0xa] = 0, [0xb] = 0,
+		[0xc] = 0, [0xd] = 0, [0xe] = 0, [0xf] = 0,
+	};
+	int r = 0;
 
-	while ((i & 1) != 1) {
-		i>>=1;
-		count++;
+	if (!(a & (0xffff << 16))) {
+		r += 16;
+		a <<= 16;
 	}
-	return count;
+
+	if (!(a & (0xff << 24))) {
+		r += 8;
+		a <<= 8;
+	}
+
+	if (!(a & (0xf << 28))) {
+		r += 4;
+		a <<= 4;
+	}
+
+	return r + four_bit_table[a >> 28];
 }