1*412f47f9SXin Li/* 2*412f47f9SXin Li * strchr/strchrnul - find a character in a string 3*412f47f9SXin Li * 4*412f47f9SXin Li * Copyright (c) 2018-2022, Arm Limited. 5*412f47f9SXin Li * SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception 6*412f47f9SXin Li */ 7*412f47f9SXin Li 8*412f47f9SXin Li#include "asmdefs.h" 9*412f47f9SXin Li 10*412f47f9SXin Li#if __ARM_FEATURE_SVE 11*412f47f9SXin Li/* Assumptions: 12*412f47f9SXin Li * 13*412f47f9SXin Li * ARMv8-a, AArch64 14*412f47f9SXin Li * SVE Available. 15*412f47f9SXin Li */ 16*412f47f9SXin Li 17*412f47f9SXin Li/* To build as strchrnul, define BUILD_STRCHRNUL before compiling this file. */ 18*412f47f9SXin Li#ifdef BUILD_STRCHRNUL 19*412f47f9SXin Li#define FUNC __strchrnul_aarch64_sve 20*412f47f9SXin Li#else 21*412f47f9SXin Li#define FUNC __strchr_aarch64_sve 22*412f47f9SXin Li#endif 23*412f47f9SXin Li 24*412f47f9SXin LiENTRY (FUNC) 25*412f47f9SXin Li PTR_ARG (0) 26*412f47f9SXin Li dup z1.b, w1 /* replicate byte across vector */ 27*412f47f9SXin Li setffr /* initialize FFR */ 28*412f47f9SXin Li ptrue p1.b /* all ones; loop invariant */ 29*412f47f9SXin Li 30*412f47f9SXin Li .p2align 4 31*412f47f9SXin Li /* Read a vector's worth of bytes, stopping on first fault. */ 32*412f47f9SXin Li0: ldff1b z0.b, p1/z, [x0, xzr] 33*412f47f9SXin Li rdffrs p0.b, p1/z 34*412f47f9SXin Li b.nlast 2f 35*412f47f9SXin Li 36*412f47f9SXin Li /* First fault did not fail: the whole vector is valid. 37*412f47f9SXin Li Avoid depending on the contents of FFR beyond the branch. */ 38*412f47f9SXin Li incb x0 /* speculate increment */ 39*412f47f9SXin Li cmpeq p2.b, p1/z, z0.b, z1.b /* search for c */ 40*412f47f9SXin Li cmpeq p3.b, p1/z, z0.b, 0 /* search for 0 */ 41*412f47f9SXin Li orrs p4.b, p1/z, p2.b, p3.b /* c | 0 */ 42*412f47f9SXin Li b.none 0b 43*412f47f9SXin Li decb x0 /* undo speculate */ 44*412f47f9SXin Li 45*412f47f9SXin Li /* Found C or 0. */ 46*412f47f9SXin Li1: brka p4.b, p1/z, p4.b /* find first such */ 47*412f47f9SXin Li sub x0, x0, 1 /* adjust pointer for that byte */ 48*412f47f9SXin Li incp x0, p4.b 49*412f47f9SXin Li#ifndef BUILD_STRCHRNUL 50*412f47f9SXin Li ptest p4, p2.b /* was first in c? */ 51*412f47f9SXin Li csel x0, xzr, x0, none /* if there was no c, return null */ 52*412f47f9SXin Li#endif 53*412f47f9SXin Li ret 54*412f47f9SXin Li 55*412f47f9SXin Li /* First fault failed: only some of the vector is valid. 56*412f47f9SXin Li Perform the comparision only on the valid bytes. */ 57*412f47f9SXin Li2: cmpeq p2.b, p0/z, z0.b, z1.b /* search for c */ 58*412f47f9SXin Li cmpeq p3.b, p0/z, z0.b, 0 /* search for 0 */ 59*412f47f9SXin Li orrs p4.b, p0/z, p2.b, p3.b /* c | 0 */ 60*412f47f9SXin Li b.any 1b 61*412f47f9SXin Li 62*412f47f9SXin Li /* No C or 0 found. Re-init FFR, increment, and loop. */ 63*412f47f9SXin Li setffr 64*412f47f9SXin Li incp x0, p0.b 65*412f47f9SXin Li b 0b 66*412f47f9SXin Li 67*412f47f9SXin LiEND (FUNC) 68*412f47f9SXin Li 69*412f47f9SXin Li#endif 70*412f47f9SXin Li 71