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/*
* memchr - find a character in a memory zone
*
* Copyright (c) 2018-2022, Arm Limited.
* SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception
*/
#include "asmdefs.h"
#if __ARM_FEATURE_SVE
/* Assumptions:
*
* ARMv8-a, AArch64
* SVE Available.
*/
ENTRY (__memchr_aarch64_sve)
PTR_ARG (0)
SIZE_ARG (2)
dup z1.b, w1 /* duplicate c to a vector */
setffr /* initialize FFR */
mov x3, 0 /* initialize off */
.p2align 4
0: whilelo p1.b, x3, x2 /* make sure off < max */
b.none 9f
/* Read a vector's worth of bytes, bounded by max,
stopping on first fault. */
ldff1b z0.b, p1/z, [x0, x3]
rdffrs p0.b, p1/z
b.nlast 2f
/* First fault did not fail: the vector bounded by max is valid.
Avoid depending on the contents of FFR beyond the branch. */
incb x3 /* speculate increment */
cmpeq p2.b, p1/z, z0.b, z1.b /* search for c */
b.none 0b
decb x3 /* undo speculate */
/* Found C. */
1: brkb p2.b, p1/z, p2.b /* find the first c */
add x0, x0, x3 /* form partial pointer */
incp x0, p2.b /* form final pointer to c */
ret
/* First fault failed: only some of the vector is valid.
Perform the comparision only on the valid bytes. */
2: cmpeq p2.b, p0/z, z0.b, z1.b
b.any 1b
/* No C found. Re-init FFR, increment, and loop. */
setffr
incp x3, p0.b
b 0b
/* Found end of count. */
9: mov x0, 0 /* return null */
ret
END (__memchr_aarch64_sve)
#endif
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