1 /* 2 * strchr/strchrnul - find a character in a string 3 * 4 * Copyright (c) 2018-2021, Arm Limited. 5 * SPDX-License-Identifier: MIT 6 */ 7 8 #include "../asmdefs.h" 9 10 #if __ARM_FEATURE_SVE 11 /* Assumptions: 12 * 13 * ARMv8-a, AArch64 14 * SVE Available. 15 */ 16 17 /* To build as strchrnul, define BUILD_STRCHRNUL before compiling this file. */ 18 #ifdef BUILD_STRCHRNUL 19 #define FUNC __strchrnul_aarch64_sve 20 #else 21 #define FUNC __strchr_aarch64_sve 22 #endif 23 24 ENTRY (FUNC) 25 PTR_ARG (0) 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. */ 32 0: 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. */ 46 1: 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. */ 57 2: 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 67 END (FUNC) 68 69 #endif 70 71