Module Name: src
Committed By: matt
Date: Sat Dec 15 19:26:34 UTC 2012
Added Files:
src/common/lib/libc/arch/arm/string: strlen_neon.S
Log Message:
Add a NEON implementation of strlen.
To generate a diff of this commit:
cvs rdiff -u -r0 -r1.1 src/common/lib/libc/arch/arm/string/strlen_neon.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_neon.S
diff -u /dev/null src/common/lib/libc/arch/arm/string/strlen_neon.S:1.1
--- /dev/null Sat Dec 15 19:26:34 2012
+++ src/common/lib/libc/arch/arm/string/strlen_neon.S Sat Dec 15 19:26:34 2012
@@ -0,0 +1,85 @@
+/*-
+ * 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_neon.S,v 1.1 2012/12/15 19:26:34 matt Exp $")
+ .text
+
+ENTRY(strlen)
+ mov ip, r0 /* we r0 for return value */
+ ands r1, r0, #15 /* verify qword alignment */
+ neg r0, r1 /* subtract misalignment from count */
+ veor q2, q2, q2 /* clear mask */
+ mov r3, #7 /* NBBY - 1 */
+ vdup.32 q3, r3 /* dup throughout q3 */
+ beq .Lmain_loop
+ veor q0, q0, q0 /* clear q0 */
+ vmvn q2, q2 /* set all 16 bytes of mask to all 1s */
+ bic ip, ip, #15 /* qword align string address */
+ lsl r2, r1, #3 /* convert to bits */
+ neg r2, r2 /* make negative since we are shifting right */
+ tst r1, #8 /* do we need skip the first 8? */
+ bne 1f /* yes, we need to skip */
+ veor d4, d4, d4 /* clear lower 8 bytes (upper is set) */
+ vmov s2, r2 /* set shift amount for upper half */
+ b 2f
+1: vmov s0, r2 /* set shift amount for lower half */
+2: vshl.u64 q2, q2, q0 /* shift */
+ /*
+ * Main loop. Load 16 bytes, do a clz,
+ */
+.Lmain_loop:
+ vld1.64 {d0, d1}, [ip:128]! /* load qword */
+#ifdef __ARMEL__
+ vrev64.8 q0, q0 /* convert to BE for clz */
+#endif
+ vswp d0, d1 /* swap dwords to get BE qword */
+ vorr q0, q0, q2 /* or "in" leading byte mask */
+ veor q2, q2, q2 /* clear byte mask */
+ vceq.i8 q1, q0, #0 /* test each byte for 0 */
+ vclz.i32 q1, q1 /* count leading zeroes to find the 0 byte */
+ vadd.i32 q1, q1, q3 /* round up to byte bounary */
+ vshr.u32 q1, q1, #3 /* convert to bytes */
+ vmov r2, r3, d3 /* get lo & hi counts */
+ add r0, r0, r3 /* add bytes to count */
+ cmp r3, #4 /* less than 4 means a NUL encountered */
+ bxlt lr /* return */
+ add r0, r0, r2 /* add bytes to count */
+ cmp r2, #4 /* less than 4 means a NUL encountered */
+ bxlt lr /* return */
+ vmov r2, r3, d2 /* get lo & hi counts */
+ add r0, r0, r3 /* add bytes to count */
+ cmp r3, #4 /* less than 4 means a NUL encountered */
+ bxlt lr /* return */
+ add r0, r0, r2 /* add bytes to count */
+ cmp r2, #4 /* less than 4 means a NUL encountered */
+ bxlt lr /* return */
+ b .Lmain_loop
+END(strlen)
