2014-06-11 18:42:54 +08:00
|
|
|
/*
|
2023-09-12 16:33:09 +08:00
|
|
|
* strchrnul - find a character or nul in a string
|
|
|
|
*
|
|
|
|
* Copyright (c) 2014-2022, Arm Limited.
|
|
|
|
* SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception
|
|
|
|
*/
|
2014-06-11 18:42:54 +08:00
|
|
|
#if (defined (__OPTIMIZE_SIZE__) || defined (PREFER_SIZE_OVER_SPEED))
|
|
|
|
/* See strchrnul-stub.c */
|
|
|
|
#else
|
|
|
|
|
|
|
|
/* Assumptions:
|
|
|
|
*
|
|
|
|
* ARMv8-a, AArch64
|
|
|
|
* Neon Available.
|
|
|
|
*/
|
|
|
|
|
2023-09-12 16:33:09 +08:00
|
|
|
#include "asmdefs.h"
|
|
|
|
|
2014-06-11 18:42:54 +08:00
|
|
|
/* Arguments and results. */
|
|
|
|
#define srcin x0
|
|
|
|
#define chrin w1
|
|
|
|
|
|
|
|
#define result x0
|
|
|
|
|
|
|
|
#define src x2
|
|
|
|
#define tmp1 x3
|
|
|
|
#define wtmp2 w4
|
|
|
|
#define tmp3 x5
|
|
|
|
|
|
|
|
#define vrepchr v0
|
|
|
|
#define vdata1 v1
|
|
|
|
#define vdata2 v2
|
|
|
|
#define vhas_nul1 v3
|
|
|
|
#define vhas_nul2 v4
|
|
|
|
#define vhas_chr1 v5
|
|
|
|
#define vhas_chr2 v6
|
2014-12-10 17:35:10 +08:00
|
|
|
#define vrepmask v7
|
2014-06-11 18:42:54 +08:00
|
|
|
#define vend1 v16
|
|
|
|
|
|
|
|
/* Core algorithm.
|
|
|
|
|
|
|
|
For each 32-byte hunk we calculate a 64-bit syndrome value, with
|
|
|
|
two bits per byte (LSB is always in bits 0 and 1, for both big
|
|
|
|
and little-endian systems). For each tuple, bit 0 is set iff
|
|
|
|
the relevant byte matched the requested character or nul. Since the
|
|
|
|
bits in the syndrome reflect exactly the order in which things occur
|
|
|
|
in the original string a count_trailing_zeros() operation will
|
|
|
|
identify exactly which byte is causing the termination. */
|
|
|
|
|
|
|
|
/* Locals and temporaries. */
|
|
|
|
|
2023-09-12 16:33:09 +08:00
|
|
|
ENTRY (strchrnul)
|
|
|
|
PTR_ARG (0)
|
2014-06-11 18:42:54 +08:00
|
|
|
/* Magic constant 0x40100401 to allow us to identify which lane
|
|
|
|
matches the termination condition. */
|
|
|
|
mov wtmp2, #0x0401
|
|
|
|
movk wtmp2, #0x4010, lsl #16
|
|
|
|
dup vrepchr.16b, chrin
|
|
|
|
bic src, srcin, #31 /* Work with aligned 32-byte hunks. */
|
|
|
|
dup vrepmask.4s, wtmp2
|
|
|
|
ands tmp1, srcin, #31
|
2023-09-12 16:33:09 +08:00
|
|
|
b.eq L(loop)
|
2014-06-11 18:42:54 +08:00
|
|
|
|
|
|
|
/* Input string is not 32-byte aligned. Rather than forcing
|
|
|
|
the padding bytes to a safe value, we calculate the syndrome
|
|
|
|
for all the bytes, but then mask off those bits of the
|
|
|
|
syndrome that are related to the padding. */
|
|
|
|
ld1 {vdata1.16b, vdata2.16b}, [src], #32
|
|
|
|
neg tmp1, tmp1
|
|
|
|
cmeq vhas_chr1.16b, vdata1.16b, vrepchr.16b
|
|
|
|
cmeq vhas_chr2.16b, vdata2.16b, vrepchr.16b
|
2023-09-12 16:33:09 +08:00
|
|
|
cmhs vhas_nul1.16b, vhas_chr1.16b, vdata1.16b
|
|
|
|
cmhs vhas_nul2.16b, vhas_chr2.16b, vdata2.16b
|
|
|
|
and vhas_chr1.16b, vhas_nul1.16b, vrepmask.16b
|
|
|
|
and vhas_chr2.16b, vhas_nul2.16b, vrepmask.16b
|
2014-06-11 18:42:54 +08:00
|
|
|
lsl tmp1, tmp1, #1
|
|
|
|
addp vend1.16b, vhas_chr1.16b, vhas_chr2.16b // 256->128
|
|
|
|
mov tmp3, #~0
|
|
|
|
addp vend1.16b, vend1.16b, vend1.16b // 128->64
|
|
|
|
lsr tmp1, tmp3, tmp1
|
|
|
|
|
2023-09-12 16:33:09 +08:00
|
|
|
mov tmp3, vend1.d[0]
|
2014-06-11 18:42:54 +08:00
|
|
|
bic tmp1, tmp3, tmp1 // Mask padding bits.
|
2023-09-12 16:33:09 +08:00
|
|
|
cbnz tmp1, L(tail)
|
2014-06-11 18:42:54 +08:00
|
|
|
|
2023-09-12 16:33:09 +08:00
|
|
|
.p2align 4
|
|
|
|
L(loop):
|
2014-06-11 18:42:54 +08:00
|
|
|
ld1 {vdata1.16b, vdata2.16b}, [src], #32
|
|
|
|
cmeq vhas_chr1.16b, vdata1.16b, vrepchr.16b
|
|
|
|
cmeq vhas_chr2.16b, vdata2.16b, vrepchr.16b
|
2023-09-12 16:33:09 +08:00
|
|
|
cmhs vhas_nul1.16b, vhas_chr1.16b, vdata1.16b
|
|
|
|
cmhs vhas_nul2.16b, vhas_chr2.16b, vdata2.16b
|
|
|
|
orr vend1.16b, vhas_nul1.16b, vhas_nul2.16b
|
|
|
|
umaxp vend1.16b, vend1.16b, vend1.16b
|
|
|
|
mov tmp1, vend1.d[0]
|
|
|
|
cbz tmp1, L(loop)
|
2014-06-11 18:42:54 +08:00
|
|
|
|
|
|
|
/* Termination condition found. Now need to establish exactly why
|
|
|
|
we terminated. */
|
2023-09-12 16:33:09 +08:00
|
|
|
and vhas_chr1.16b, vhas_nul1.16b, vrepmask.16b
|
|
|
|
and vhas_chr2.16b, vhas_nul2.16b, vrepmask.16b
|
2014-06-11 18:42:54 +08:00
|
|
|
addp vend1.16b, vhas_chr1.16b, vhas_chr2.16b // 256->128
|
|
|
|
addp vend1.16b, vend1.16b, vend1.16b // 128->64
|
|
|
|
|
2023-09-12 16:33:09 +08:00
|
|
|
mov tmp1, vend1.d[0]
|
|
|
|
L(tail):
|
2014-06-11 18:42:54 +08:00
|
|
|
/* Count the trailing zeros, by bit reversing... */
|
|
|
|
rbit tmp1, tmp1
|
|
|
|
/* Re-bias source. */
|
|
|
|
sub src, src, #32
|
|
|
|
clz tmp1, tmp1 /* ... and counting the leading zeros. */
|
|
|
|
/* tmp1 is twice the offset into the fragment. */
|
|
|
|
add result, src, tmp1, lsr #1
|
|
|
|
ret
|
|
|
|
|
2023-09-12 16:33:09 +08:00
|
|
|
END (strchrnul)
|
2014-06-11 18:42:54 +08:00
|
|
|
#endif
|