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/* Miscellaneous functions used in string implementations. RISC-V version.
Copyright (C) 2025-2026 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 _RISCV_STRING_MISC_H
#define _RISCV_STRING_MISC_H 1
#include <limits.h>
#include <endian.h>
#include <string-optype.h>
#if defined __riscv_zbkb
/* Extract the byte at index IDX from word X, with index 0 being the
least significant byte. */
static __always_inline unsigned char
extractbyte (op_t x, unsigned int idx)
{
if (__BYTE_ORDER == __LITTLE_ENDIAN)
return x >> (idx * CHAR_BIT);
else
return x >> (sizeof (x) - 1 - idx) * CHAR_BIT;
}
/* Setup an word with each byte being c_in. For instance, on a 64 bits
machine with input as 0xce the functions returns 0xcececececececece. */
static __always_inline op_t
repeat_bytes (unsigned char c_in)
{
op_t c = c_in;
#if __riscv_xlen == 64
/* 8bit -> 16bit -> 32bit -> 64bit pattern replication */
__asm__ ("packh %0, %1, %1\n\t"
"packw %0, %0, %0\n\t"
"pack %0, %0, %0"
: "=r"(c) : "r"(c));
#elif __riscv_xlen == 32
/* 8bit -> 16bit -> 32bit pattern replication */
__asm__ ("packh %0, %1, %1\n\t"
"pack %0, %0, %0"
: "=r"(c) : "r"(c));
#else
#error unsupported xlen
#endif
return c;
}
#else
#include <sysdeps/generic/string-misc.h>
#endif
#endif /* _RISCV_STRING_MISC_H */
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