diff options
Diffstat (limited to 'libc/string/aarch64/memset.S')
| -rw-r--r-- | libc/string/aarch64/memset.S | 189 |
1 files changed, 189 insertions, 0 deletions
diff --git a/libc/string/aarch64/memset.S b/libc/string/aarch64/memset.S new file mode 100644 index 000000000..d6686bedc --- /dev/null +++ b/libc/string/aarch64/memset.S @@ -0,0 +1,189 @@ +/* Copyright (C) 2012-2017 Free Software Foundation, Inc. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library. If not, see + <http://www.gnu.org/licenses/>. */ + +#include <sysdep.h> + +/* Assumptions: + * + * ARMv8-a, AArch64, unaligned accesses + * + */ + +#define dstin x0 +#define val x1 +#define valw w1 +#define count x2 +#define dst x3 +#define dstend x4 +#define tmp1 x5 +#define tmp1w w5 +#define tmp2 x6 +#define tmp2w w6 +#define zva_len x7 +#define zva_lenw w7 + +ENTRY_ALIGN (memset, 6) + + 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 3 + nop +L(set_long): + and valw, valw, 255 + bic dst, dstin, 15 + str q0, [dstin] + cmp count, 256 + ccmp valw, 0, 0, cs + b.eq L(try_zva) +L(no_zva): + sub count, dstend, dst /* Count is 16 too large. */ + add dst, dst, 16 + sub count, count, 64 + 16 /* Adjust count and bias for loop. */ +1: stp q0, q0, [dst], 64 + stp q0, q0, [dst, -32] +L(tail64): + subs count, count, 64 + b.hi 1b +2: stp q0, q0, [dstend, -64] + stp q0, q0, [dstend, -32] + ret + + .p2align 3 +L(try_zva): + mrs tmp1, dczid_el0 + tbnz tmp1w, 4, L(no_zva) + and tmp1w, tmp1w, 15 + cmp tmp1w, 4 /* ZVA size is 64 bytes. */ + b.ne L(zva_128) + + /* Write the first and last 64 byte aligned block using stp rather + than using DC ZVA. This is faster on some cores. + */ +L(zva_64): + str q0, [dst, 16] + stp q0, q0, [dst, 32] + bic dst, dst, 63 + stp q0, q0, [dst, 64] + stp q0, q0, [dst, 96] + sub count, dstend, dst /* Count is now 128 too large. */ + sub count, count, 128+64+64 /* Adjust count and bias for loop. */ + add dst, dst, 128 + nop +1: dc zva, dst + add dst, dst, 64 + subs count, count, 64 + b.hi 1b + stp q0, q0, [dst, 0] + stp q0, q0, [dst, 32] + stp q0, q0, [dstend, -64] + stp q0, q0, [dstend, -32] + ret + + .p2align 3 +L(zva_128): + cmp tmp1w, 5 /* ZVA size is 128 bytes. */ + b.ne L(zva_other) + + str q0, [dst, 16] + stp q0, q0, [dst, 32] + stp q0, q0, [dst, 64] + stp q0, q0, [dst, 96] + bic dst, dst, 127 + sub count, dstend, dst /* Count is now 128 too large. */ + sub count, count, 128+128 /* Adjust count and bias for loop. */ + add dst, dst, 128 +1: dc zva, dst + add dst, dst, 128 + subs count, count, 128 + b.hi 1b + stp q0, q0, [dstend, -128] + stp q0, q0, [dstend, -96] + stp q0, q0, [dstend, -64] + stp q0, q0, [dstend, -32] + ret + +L(zva_other): + mov tmp2w, 4 + lsl zva_lenw, tmp2w, tmp1w + add tmp1, zva_len, 64 /* Max alignment bytes written. */ + cmp count, tmp1 + blo L(no_zva) + + sub tmp2, zva_len, 1 + add tmp1, dst, zva_len + add dst, dst, 16 + subs count, tmp1, dst /* Actual alignment bytes to write. */ + bic tmp1, tmp1, tmp2 /* Aligned dc zva start address. */ + beq 2f +1: stp q0, q0, [dst], 64 + stp q0, q0, [dst, -32] + subs count, count, 64 + b.hi 1b +2: mov dst, tmp1 + sub count, dstend, tmp1 /* Remaining bytes to write. */ + subs count, count, zva_len + b.lo 4f +3: dc zva, dst + add dst, dst, zva_len + subs count, count, zva_len + b.hs 3b +4: add count, count, zva_len + b L(tail64) + +END (memset) +libc_hidden_def (memset) |