sysdeps/riscv/string-fza.h

   1 /* Zero byte detection; basics.  RISCV version.
   2    Copyright (C) 2023-2024 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #ifndef _RISCV_STRING_FZA_H
  20 #define _RISCV_STRING_FZA_H 1
  21
  22 #if defined __riscv_zbb || defined __riscv_xtheadbb
  23 /* With bitmap extension we can use orc.b to find all zero bytes.  */
  24 # include <string-misc.h>
  25 # include <string-optype.h>
  26
  27 /* The functions return a byte mask.  */
  28 typedef op_t find_t;
  29
  30 /* This function returns 0xff for each byte that is zero in X.  */
  31 static __always_inline find_t
  32 find_zero_all (op_t x)
  33 {
  34   find_t r;
  35 #ifdef __riscv_xtheadbb
  36   asm ("th.tstnbz %0, %1" : "=r" (r) : "r" (x));
  37   return r;
  38 #else
  39   asm ("orc.b %0, %1" : "=r" (r) : "r" (x));
  40   return ~r;
  41 #endif
  42 }
  43
  44 /* This function returns 0xff for each byte that is equal between X1 and
  45    X2.  */
  46 static __always_inline find_t
  47 find_eq_all (op_t x1, op_t x2)
  48 {
  49   return find_zero_all (x1 ^ x2);
  50 }
  51
  52 /* Identify zero bytes in X1 or equality between X1 and X2.  */
  53 static __always_inline find_t
  54 find_zero_eq_all (op_t x1, op_t x2)
  55 {
  56   return find_zero_all (x1) | find_eq_all (x1, x2);
  57 }
  58
  59 /* Identify zero bytes in X1 or inequality between X1 and X2.  */
  60 static __always_inline find_t
  61 find_zero_ne_all (op_t x1, op_t x2)
  62 {
  63   return find_zero_all (x1) | ~find_eq_all (x1, x2);
  64 }
  65
  66 /* Define the "inexact" versions in terms of the exact versions.  */
  67 # define find_zero_low          find_zero_all
  68 # define find_eq_low            find_eq_all
  69 # define find_zero_eq_low       find_zero_eq_all
  70 #else
  71 #include <sysdeps/generic/string-fza.h>
  72 #endif
  73
  74 #endif /* _RISCV_STRING_FZA_H  */