/* Optimized rawmemchr implementation using basic LoongArch instructions.
   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
   <https://www.gnu.org/licenses/>.  */

#include <sysdep.h>
#include <sys/regdef.h>
#include <sys/asm.h>

#if IS_IN (libc)
# define RAWMEMCHR_NAME __rawmemchr_aligned
#else
# define RAWMEMCHR_NAME __rawmemchr
#endif

LEAF(RAWMEMCHR_NAME, 6)
    andi        t1, a0, 0x7
    bstrins.d   a0, zero, 2, 0
    lu12i.w     a2, 0x01010
    bstrins.d   a1, a1, 15, 8

    ld.d        t0, a0, 0
    slli.d      t1, t1, 3
    ori         a2, a2, 0x101
    bstrins.d   a1, a1, 31, 16

    li.w        t8, -1
    bstrins.d   a1, a1, 63, 32
    bstrins.d   a2, a2, 63, 32
    sll.d       t2, t8, t1

    sll.d       t3, a1, t1
    orn         t0, t0, t2
    slli.d      a3, a2, 7
    beqz        a1, L(find_zero)

    xor         t0, t0, t3
    sub.d       t1, t0, a2
    andn        t2, a3, t0
    and         t3, t1, t2

    bnez        t3, L(count_pos)
    addi.d      a0, a0, 8

L(loop):
    ld.d        t0, a0, 0
    xor         t0, t0, a1

    sub.d       t1, t0, a2
    andn        t2, a3, t0
    and         t3, t1, t2
    bnez        t3, L(count_pos)

    ld.d        t0, a0, 8
    addi.d      a0, a0, 16
    xor         t0, t0, a1
    sub.d       t1, t0, a2

    andn        t2, a3, t0
    and         t3, t1, t2
    beqz        t3, L(loop)
    addi.d      a0, a0, -8
L(count_pos):
    ctz.d       t0, t3
    srli.d      t0, t0, 3
    add.d       a0, a0, t0
    jr          ra

L(loop_7bit):
    ld.d        t0, a0, 0
L(find_zero):
    sub.d       t1, t0, a2
    and         t2, t1, a3
    bnez        t2, L(more_check)

    ld.d        t0, a0, 8
    addi.d      a0, a0, 16
    sub.d       t1, t0, a2
    and         t2, t1, a3

    beqz        t2, L(loop_7bit)
    addi.d      a0, a0, -8

L(more_check):
    andn        t2, a3, t0
    and         t3, t1, t2
    bnez        t3, L(count_pos)
    addi.d      a0, a0, 8

L(loop_8bit):
    ld.d        t0, a0, 0

    sub.d       t1, t0, a2
    andn        t2, a3, t0
    and         t3, t1, t2
    bnez        t3, L(count_pos)

    ld.d        t0, a0, 8
    addi.d      a0, a0, 16
    sub.d       t1, t0, a2

    andn        t2, a3, t0
    and         t3, t1, t2
    beqz        t3, L(loop_8bit)

    addi.d      a0, a0, -8
    b           L(count_pos)

END(RAWMEMCHR_NAME)

libc_hidden_builtin_def (__rawmemchr)