| /* |
| * memset - fill memory with a constant byte |
| * |
| * Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| * See https://llvm.org/LICENSE.txt for license information. |
| * SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| */ |
| |
| /* Assumptions: |
| * |
| * ARMv8-a, AArch64, Advanced SIMD, unaligned accesses. |
| * |
| */ |
| |
| #include "../asmdefs.h" |
| |
| #define dstin x0 |
| #define val x1 |
| #define valw w1 |
| #define count x2 |
| #define dst x3 |
| #define dstend x4 |
| #define zva_val x5 |
| |
| ENTRY (__memset_aarch64) |
| |
| dup v0.16B, valw |
| add dstend, dstin, count |
| |
| cmp count, 96 |
| b.hi L(set_long) |
| cmp count, 16 |
| b.hs L(set_medium) |
| mov val, v0.D[0] |
| |
| /* Set 0..15 bytes. */ |
| tbz count, 3, 1f |
| str val, [dstin] |
| str val, [dstend, -8] |
| ret |
| nop |
| 1: tbz count, 2, 2f |
| str valw, [dstin] |
| str valw, [dstend, -4] |
| ret |
| 2: cbz count, 3f |
| strb valw, [dstin] |
| tbz count, 1, 3f |
| strh valw, [dstend, -2] |
| 3: ret |
| |
| /* Set 17..96 bytes. */ |
| L(set_medium): |
| str q0, [dstin] |
| tbnz count, 6, L(set96) |
| str q0, [dstend, -16] |
| tbz count, 5, 1f |
| str q0, [dstin, 16] |
| str q0, [dstend, -32] |
| 1: ret |
| |
| .p2align 4 |
| /* Set 64..96 bytes. Write 64 bytes from the start and |
| 32 bytes from the end. */ |
| L(set96): |
| str q0, [dstin, 16] |
| stp q0, q0, [dstin, 32] |
| stp q0, q0, [dstend, -32] |
| ret |
| |
| .p2align 4 |
| L(set_long): |
| and valw, valw, 255 |
| bic dst, dstin, 15 |
| str q0, [dstin] |
| cmp count, 160 |
| ccmp valw, 0, 0, hs |
| b.ne L(no_zva) |
| |
| #ifndef SKIP_ZVA_CHECK |
| mrs zva_val, dczid_el0 |
| and zva_val, zva_val, 31 |
| cmp zva_val, 4 /* ZVA size is 64 bytes. */ |
| b.ne L(no_zva) |
| #endif |
| str q0, [dst, 16] |
| stp q0, q0, [dst, 32] |
| bic dst, dst, 63 |
| sub count, dstend, dst /* Count is now 64 too large. */ |
| sub count, count, 128 /* Adjust count and bias for loop. */ |
| |
| .p2align 4 |
| L(zva_loop): |
| add dst, dst, 64 |
| dc zva, dst |
| subs count, count, 64 |
| b.hi L(zva_loop) |
| stp q0, q0, [dstend, -64] |
| stp q0, q0, [dstend, -32] |
| ret |
| |
| L(no_zva): |
| sub count, dstend, dst /* Count is 16 too large. */ |
| sub dst, dst, 16 /* Dst is biased by -32. */ |
| sub count, count, 64 + 16 /* Adjust count and bias for loop. */ |
| L(no_zva_loop): |
| stp q0, q0, [dst, 32] |
| stp q0, q0, [dst, 64]! |
| subs count, count, 64 |
| b.hi L(no_zva_loop) |
| stp q0, q0, [dstend, -64] |
| stp q0, q0, [dstend, -32] |
| ret |
| |
| END (__memset_aarch64) |
