FreeBSD/Linux Kernel Cross Reference
sys/contrib/zstd/lib/freebsd/zstd_kfreebsd.c

     /*-
      * Copyright (c) 2018 Conrad Meyer <cem@freebsd.org>
      * All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
      * 1. Redistributions of source code must retain the above copyright
      *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     * $FreeBSD$
     */
    
    #include "zstd_kfreebsd.h"
    #include <sys/param.h>
    #include <sys/endian.h>
    
    #ifndef _KERNEL
    #include <strings.h>
    #endif
    
    /*
     * The kernel as a standalone target does not link against libgcc or
     * libcompiler-rt. On platforms (e.g., MIPS and RISCV) that do not have a
     * direct assembly implementation of the relevant builtin functions that zstd
     * references, the compiler converts them into calls to the runtime library
     * intrinsics.  Since the kernel does not link against the runtime libraries,
     * this results in a failure to link the kernel.
     *
     * The goal of the following definitions is to use supported kernel constructs
     * to implement the same functionality, without adding diff to the Zstd contrib
     * code.
     *
     * A subsequent enhancement might create a mini compiler-rt library for kernel
     * use and move these over there instead.
     */
    
    /* Swap endianness */
    int
    __bswapsi2(int x)
    {
            return (bswap32(x));
    }
    
    long long
    __bswapdi2(long long x)
    {
            return (bswap64(x));
    }
    
    /* Count trailing zeros */
    int
    __ctzsi2(int x)
    {
           if (x == 0)
                   return (sizeof(x) * NBBY);
           return (ffs(x) - 1);
    }
    
    long long
    __ctzdi2(long long x)
    {
           if (x == 0)
                   return (sizeof(x) * NBBY);
           return (ffsll(x) - 1);
    }
    
    /* Count leading zeros */
    int
    __clzsi2(int x)
    {
           return (sizeof(x) * NBBY - fls(x));
    }
    
    long long
    __clzdi2(long long x)
    {
           return (sizeof(x) * NBBY - flsll(x));
    }

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