1/* 2 * strchr/strchrnul - find a character in a string 3 * 4 * Copyright (c) 2018-2022, Arm Limited. 5 * SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception 6 */ 7 8#include "asmdefs.h" 9 10.arch armv8-a+sve 11 12/* Assumptions: 13 * 14 * ARMv8-a, AArch64 15 * SVE Available. 16 */ 17 18/* To build as strchrnul, define BUILD_STRCHRNUL before compiling this file. */ 19#ifdef BUILD_STRCHRNUL 20#define FUNC __strchrnul_aarch64_sve 21#else 22#define FUNC __strchr_aarch64_sve 23#endif 24 25ENTRY (FUNC) 26 dup z1.b, w1 /* replicate byte across vector */ 27 setffr /* initialize FFR */ 28 ptrue p1.b /* all ones; loop invariant */ 29 30 .p2align 4 31 /* Read a vector's worth of bytes, stopping on first fault. */ 320: ldff1b z0.b, p1/z, [x0, xzr] 33 rdffrs p0.b, p1/z 34 b.nlast 2f 35 36 /* First fault did not fail: the whole vector is valid. 37 Avoid depending on the contents of FFR beyond the branch. */ 38 incb x0 /* speculate increment */ 39 cmpeq p2.b, p1/z, z0.b, z1.b /* search for c */ 40 cmpeq p3.b, p1/z, z0.b, 0 /* search for 0 */ 41 orrs p4.b, p1/z, p2.b, p3.b /* c | 0 */ 42 b.none 0b 43 decb x0 /* undo speculate */ 44 45 /* Found C or 0. */ 461: brka p4.b, p1/z, p4.b /* find first such */ 47 sub x0, x0, 1 /* adjust pointer for that byte */ 48 incp x0, p4.b 49#ifndef BUILD_STRCHRNUL 50 ptest p4, p2.b /* was first in c? */ 51 csel x0, xzr, x0, none /* if there was no c, return null */ 52#endif 53 ret 54 55 /* First fault failed: only some of the vector is valid. 56 Perform the comparision only on the valid bytes. */ 572: cmpeq p2.b, p0/z, z0.b, z1.b /* search for c */ 58 cmpeq p3.b, p0/z, z0.b, 0 /* search for 0 */ 59 orrs p4.b, p0/z, p2.b, p3.b /* c | 0 */ 60 b.any 1b 61 62 /* No C or 0 found. Re-init FFR, increment, and loop. */ 63 setffr 64 incp x0, p0.b 65 b 0b 66 67END (FUNC) 68