Module Name: src
Committed By: matt
Date: Wed Jan 2 15:24:21 UTC 2013
Added Files:
src/common/lib/libc/arch/arm/string: strlen.S
Removed Files:
src/common/lib/libc/arch/arm/string: strlen_armv6.S
Log Message:
Rename strlen_armv6.S to strlen.S since this is no longer armv6 dependent.
To generate a diff of this commit:
cvs rdiff -u -r0 -r1.1 src/common/lib/libc/arch/arm/string/strlen.S
cvs rdiff -u -r1.3 -r0 src/common/lib/libc/arch/arm/string/strlen_armv6.S
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Added files:
Index: src/common/lib/libc/arch/arm/string/strlen.S
diff -u /dev/null src/common/lib/libc/arch/arm/string/strlen.S:1.1
--- /dev/null Wed Jan 2 15:24:21 2013
+++ src/common/lib/libc/arch/arm/string/strlen.S Wed Jan 2 15:24:21 2013
@@ -0,0 +1,121 @@
+/*-
+ * Copyright (c) 2012 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * This code is derived from software contributed to The NetBSD Foundation
+ * by Matt Thomas of 3am Software Foundry.
+ *
+ * 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
+ */
+
+#include <machine/asm.h>
+
+RCSID("$NetBSD: strlen.S,v 1.1 2013/01/02 15:24:21 matt Exp $")
+
+#ifdef __ARMEL__
+#define BYTE0 0x000000ff
+#define BYTE1 0x0000ff00
+#define BYTE2 0x00ff0000
+#define BYTE3 0xff000000
+#else
+#define BYTE0 0xff000000
+#define BYTE1 0x00ff0000
+#define BYTE2 0x0000ff00
+#define BYTE3 0x000000ff
+#endif
+
+ .text
+ENTRY(strlen)
+ add ip, r0, #4 /* for the final post-inc */
+1: tst r0, #3 /* test for word alignment */
+ beq .Lpre_main_loop /* finally word aligned */
+ ldrb r3, [r0], #1 /* load a byte */
+ teq r3, #0 /* is it 0? */
+ bne 1b /* no, try next byte */
+ sub ip, ip, #3 /* subtract (4 - the NUL) */
+ sub r0, r0, ip /* subtract start */
+ RET /* return */
+.Lpre_main_loop:
+#if defined(_ARM_ARCH_6)
+#if defined(_ARM_ARCH_7)
+ movw r1, #0xfefe /* magic constant; 254 in each byte */
+#else
+ mov r1, #0xfe /* put 254 in low byte */
+ orr r1, r1, r1, lsl #8 /* move to next byte */
+#endif
+ orr r1, r1, r1, lsl #16 /* move to next halfword */
+#endif /* _ARM_ARCH_6 */
+.Lmain_loop:
+ ldr r3, [r0], #4 /* load next word */
+#if defined(_ARM_ARCH_6)
+ /*
+ * Add 254 to each byte using the UQADD8 (unsigned saturating add 8)
+ * instruction. For every non-NUL byte, the result for that byte will
+ * become 255. For NUL, it will be 254. When we complement the
+ * result, if the result is non-0 then we must have encountered a NUL.
+ */
+ uqadd8 r3, r3, r1 /* magic happens here */
+ mvns r3, r3 /* is the complemented result non-0? */
+ beq .Lmain_loop /* no, then we encountered no NULs */
+#else
+ /*
+ * No fancy shortcuts so just test each byte lane for a NUL.
+ * (other tests for NULs in a word take more instructions/cycles).
+ */
+ tst r3, #BYTE0 /* is this byte 0? */
+ tstne r3, #BYTE1 /* no, is this byte 0? */
+ tstne r3, #BYTE2 /* no, is this byte 0? */
+ tstne r3, #BYTE3 /* no, is this byte 0? */
+ bne .Lmain_loop /* no, then get next word */
+#endif
+#if defined(_ARM_ARCH_6)
+ /*
+ * We encountered a NUL. Find out where by doing a CLZ and then
+ * shifting right by 3. That will be the number of non-NUL bytes.
+ */
+#ifdef __ARMEL__
+ rev r3, r3 /* we want this in BE for the CLZ */
+#endif
+ clz r3, r3 /* count how many leading zeros */
+ add r0, r0, r3, lsr #3 /* divide that by 8 and add to count */
+#else
+ /*
+ * We encountered a NUL.
+ */
+ tst r3, #BYTE0 /* 1st byte was NUL? */
+ beq 1f /* yes, done adding */
+ add r0, r0, #1 /* we have one more non-NUL byte */
+ tst r3, #BYTE1 /* 2nd byte was NUL? */
+ beq 1f /* yes, done adding */
+ add r0, r0, #1 /* we have one more non-NUL byte */
+ tst r3, #BYTE2 /* 3rd byte was NUL? */
+ addne r0, r0, #1 /* no, we have one more non-NUL byte */
+1:
+#endif /* _ARM_ARCH_6 */
+ /*
+ * r0 now points to 4 past the NUL due to the post-inc. Subtract the
+ * start of the string (which also has 4 added to it to compensate for
+ * the post-inc.
+ */
+ sub r0, r0, ip /* subtract start to get length */
+ RET
+END(strlen)
