1  /* Zero byte detection; basics.  RISCV version.
       2     Copyright (C) 2023 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  #ifdef __riscv_zbb
      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    asm ("orc.b %0, %1" : "=r" (r) : "r" (x));
      36    return ~r;
      37  }
      38  
      39  /* This function returns 0xff for each byte that is equal between X1 and
      40     X2.  */
      41  static __always_inline find_t
      42  find_eq_all (op_t x1, op_t x2)
      43  {
      44    return find_zero_all (x1 ^ x2);
      45  }
      46  
      47  /* Identify zero bytes in X1 or equality between X1 and X2.  */
      48  static __always_inline find_t
      49  find_zero_eq_all (op_t x1, op_t x2)
      50  {
      51    return find_zero_all (x1) | find_eq_all (x1, x2);
      52  }
      53  
      54  /* Identify zero bytes in X1 or inequality between X1 and X2.  */
      55  static __always_inline find_t
      56  find_zero_ne_all (op_t x1, op_t x2)
      57  {
      58    return find_zero_all (x1) | ~find_eq_all (x1, x2);
      59  }
      60  
      61  /* Define the "inexact" versions in terms of the exact versions.  */
      62  # define find_zero_low		find_zero_all
      63  # define find_eq_low		find_eq_all
      64  # define find_zero_eq_low	find_zero_eq_all
      65  #else
      66  #include <sysdeps/generic/string-fza.h>
      67  #endif
      68  
      69  #endif /* _RISCV_STRING_FZA_H  */