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/*
* strcpy/stpcpy - copy a string returning pointer to start/end.
*
* Copyright (c) 2018, Linaro Limited
* All rights Reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * 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.
* * Neither the name of the company nor the names of its contributors
* may be used to endorse or promote products derived from this
* software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT
* HOLDER 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.
*/
/* Assumptions:
*
* ARMv8-a, AArch64
* SVE Available.
*/
.arch armv8-a+sve
.text
/* To build as stpcpy, define BUILD_STPCPY before compiling this file. */
#ifdef BUILD_STPCPY
#define FUNC stpcpy
#else
#define FUNC strcpy
#endif
.globl FUNC
.type FUNC, %function
.p2align 4
FUNC:
setffr /* initialize FFR */
ptrue p2.b, all /* all ones; loop invariant */
mov x2, 0 /* initialize offset */
.p2align 4
/* Read a vector's worth of bytes, stopping on first fault. */
0: ldff1b z0.b, p2/z, [x1, x2]
rdffrs p0.b, p2/z
b.nlast 1f
/* First fault did not fail: the whole vector is valid.
Avoid depending on the contexts of FFR beyond the branch. */
cmpeq p1.b, p2/z, z0.b, 0 /* search for zeros */
b.any 2f
/* No zero found. Store the whole vector and loop. */
st1b z0.b, p2, [x0, x2]
incb x2, all
b 0b
/* First fault failed: only some of the vector is valid.
Perform the comparison only on the valid bytes. */
1: cmpeq p1.b, p0/z, z0.b, 0 /* search for zeros */
b.any 2f
/* No zero found. Store the valid portion of the vector and loop. */
setffr /* re-init FFR */
st1b z0.b, p0, [x0, x2]
incp x2, p0.b
b 0b
/* Zero found. Crop the vector to the found zero and finish. */
2: brka p0.b, p2/z, p1.b
st1b z0.b, p0, [x0, x2]
#ifdef BUILD_STPCPY
add x0, x0, x2
sub x0, x0, 1
incp x0, p0.b
#endif
ret
.size FUNC, . - FUNC
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