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author | Richard Henderson <richard.henderson@linaro.org> | 2023-01-10 18:01:04 -0300 |
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committer | Adhemerval Zanella <adhemerval.zanella@linaro.org> | 2023-02-06 16:19:35 -0300 |
commit | 885306b2f68e4a82034cff420c8fc93c695f10bc (patch) | |
tree | 1b8915201717869ec22473e748f0b0ee460755e6 /sysdeps/arm | |
parent | 120ad6ed1ae72ed8bf46638c5a7bf6c3b239d4dc (diff) | |
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arm: Add string-fza.h
While arm has the more important string functions in assembly,
there are still a few generic routines used.
Use the UQSUB8 insn for testing of zeros.
Checked on armv7-linux-gnueabihf
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Diffstat (limited to 'sysdeps/arm')
-rw-r--r-- | sysdeps/arm/armv6t2/string-fza.h | 67 |
1 files changed, 67 insertions, 0 deletions
diff --git a/sysdeps/arm/armv6t2/string-fza.h b/sysdeps/arm/armv6t2/string-fza.h new file mode 100644 index 0000000000..76274ccca7 --- /dev/null +++ b/sysdeps/arm/armv6t2/string-fza.h @@ -0,0 +1,67 @@ +/* Zero byte detection; basics. ARM version. + Copyright (C) 2023 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + 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/>. */ + +#ifndef _STRING_FZA_H +#define _STRING_FZA_H 1 + +#include <string-misc.h> +#include <string-optype.h> + +/* The functions return a byte mask. */ +typedef op_t find_t; + +/* This function returns at least one bit set within every byte + of X that is zero. */ +static __always_inline find_t +find_zero_all (op_t x) +{ + /* Use unsigned saturated subtraction from 1 in each byte. + That leaves 1 for every byte that was zero. */ + op_t ones = repeat_bytes (0x01); + return __builtin_arm_uqsub8 (ones, x); +} + +/* Identify bytes that are equal between X1 and X2. */ +static __always_inline find_t +find_eq_all (op_t x1, op_t x2) +{ + return find_zero_all (x1 ^ x2); +} + +/* Identify zero bytes in X1 or equality between X1 and X2. */ +static __always_inline find_t +find_zero_eq_all (op_t x1, op_t x2) +{ + return find_zero_all (x1) | find_zero_all (x1 ^ x2); +} + +/* Identify zero bytes in X1 or inequality between X1 and X2. */ +static __always_inline find_t +find_zero_ne_all (op_t x1, op_t x2) +{ + /* Make use of the fact that we'll already have ONES in a register. */ + op_t ones = repeat_bytes (0x01); + return find_zero_all (x1) | (find_zero_all (x1 ^ x2) ^ ones); +} + +/* Define the "inexact" versions in terms of the exact versions. */ +#define find_zero_low find_zero_all +#define find_eq_low find_eq_all +#define find_zero_eq_low find_zero_eq_all + +#endif /* _STRING_FZA_H */ |