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3d6fcf1bd7
XTheadBb has similar instructions like Zbb, which allow optimized string processing: * th.ff0: find-first zero is a CLZ instruction. * th.tstnbz: Similar like orc.b, but with a bit-inverted result. The instructions are documented here: https://github.com/T-head-Semi/thead-extension-spec/tree/master/xtheadbb These instructions can be found in the T-Head C906 and the C910. Tested with the string tests. Signed-off-by: Christoph Müllner <christoph.muellner@vrull.eu> Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
75 lines
2.2 KiB
C
75 lines
2.2 KiB
C
/* Zero byte detection; basics. RISCV version.
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Copyright (C) 2023 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#ifndef _RISCV_STRING_FZA_H
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#define _RISCV_STRING_FZA_H 1
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#if defined __riscv_zbb || defined __riscv_xtheadbb
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/* With bitmap extension we can use orc.b to find all zero bytes. */
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# include <string-misc.h>
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# include <string-optype.h>
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/* The functions return a byte mask. */
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typedef op_t find_t;
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/* This function returns 0xff for each byte that is zero in X. */
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static __always_inline find_t
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find_zero_all (op_t x)
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{
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find_t r;
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#ifdef __riscv_xtheadbb
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asm ("th.tstnbz %0, %1" : "=r" (r) : "r" (x));
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return r;
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#else
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asm ("orc.b %0, %1" : "=r" (r) : "r" (x));
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return ~r;
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#endif
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}
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/* This function returns 0xff for each byte that is equal between X1 and
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X2. */
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static __always_inline find_t
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find_eq_all (op_t x1, op_t x2)
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{
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return find_zero_all (x1 ^ x2);
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}
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/* Identify zero bytes in X1 or equality between X1 and X2. */
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static __always_inline find_t
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find_zero_eq_all (op_t x1, op_t x2)
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{
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return find_zero_all (x1) | find_eq_all (x1, x2);
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}
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/* Identify zero bytes in X1 or inequality between X1 and X2. */
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static __always_inline find_t
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find_zero_ne_all (op_t x1, op_t x2)
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{
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return find_zero_all (x1) | ~find_eq_all (x1, x2);
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}
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/* Define the "inexact" versions in terms of the exact versions. */
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# define find_zero_low find_zero_all
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# define find_eq_low find_eq_all
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# define find_zero_eq_low find_zero_eq_all
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#else
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#include <sysdeps/generic/string-fza.h>
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#endif
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#endif /* _RISCV_STRING_FZA_H */
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