/* misc.c
 *
 * Copyright (C) 2006-2015 wolfSSL Inc.
 *
 * This file is part of wolfSSL. (formerly known as CyaSSL)
 *
 * wolfSSL is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * wolfSSL 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
 */

#ifdef HAVE_CONFIG_H
    #include <config.h>
#endif

#include <wolfssl/wolfcrypt/settings.h>

#ifndef WOLF_CRYPT_MISC_C
#define WOLF_CRYPT_MISC_C

#include <wolfssl/wolfcrypt/misc.h>

/* inlining these functions is a huge speed increase and a small size decrease, 
   because the functions are smaller than function call setup/cleanup, e.g.,
   md5 benchmark is twice as fast with inline.  If you don't want it, then
   define NO_INLINE and compile this file into wolfssl, otherwise it's used as
   a source header
 */

#ifdef NO_INLINE
    #define STATIC
#else
    #define STATIC static
#endif


#ifdef INTEL_INTRINSICS

    #include <stdlib.h>      /* get intrinsic definitions */

    /* for non visual studio probably need no long version, 32 bit only
     * i.e., _rotl and _rotr */
    #pragma intrinsic(_lrotl, _lrotr)

    STATIC INLINE word32 rotlFixed(word32 x, word32 y)
    {
        return y ? _lrotl(x, y) : x;
    }

    STATIC INLINE word32 rotrFixed(word32 x, word32 y)
    {
        return y ? _lrotr(x, y) : x;
    }

#else /* generic */

    STATIC INLINE word32 rotlFixed(word32 x, word32 y)
    {
        return (x << y) | (x >> (sizeof(y) * 8 - y));
    }   


    STATIC INLINE word32 rotrFixed(word32 x, word32 y)
    {
        return (x >> y) | (x << (sizeof(y) * 8 - y));
    }

#endif


STATIC INLINE word32 ByteReverseWord32(word32 value)
{
#ifdef PPC_INTRINSICS
    /* PPC: load reverse indexed instruction */
    return (word32)__lwbrx(&value,0);
#elif defined(KEIL_INTRINSICS)
    return (word32)__rev(value);
#elif defined(FAST_ROTATE)
    /* 5 instructions with rotate instruction, 9 without */
    return (rotrFixed(value, 8U) & 0xff00ff00) |
           (rotlFixed(value, 8U) & 0x00ff00ff);
#else
    /* 6 instructions with rotate instruction, 8 without */
    value = ((value & 0xFF00FF00) >> 8) | ((value & 0x00FF00FF) << 8);
    return rotlFixed(value, 16U);
#endif
}


STATIC INLINE void ByteReverseWords(word32* out, const word32* in,
                                    word32 byteCount)
{
    word32 count = byteCount/(word32)sizeof(word32), i;

    for (i = 0; i < count; i++)
        out[i] = ByteReverseWord32(in[i]);

}


#ifdef WORD64_AVAILABLE


STATIC INLINE word64 rotlFixed64(word64 x, word64 y)
{
    return (x << y) | (x >> (sizeof(y) * 8 - y));
}  


STATIC INLINE word64 rotrFixed64(word64 x, word64 y)
{
    return (x >> y) | (x << (sizeof(y) * 8 - y));
}


STATIC INLINE word64 ByteReverseWord64(word64 value)
{
#ifdef WOLFCRYPT_SLOW_WORD64
	return (word64)(ByteReverseWord32((word32)value)) << 32 | 
                    ByteReverseWord32((word32)(value>>32));
#else
	value = ((value & W64LIT(0xFF00FF00FF00FF00)) >> 8) |
            ((value & W64LIT(0x00FF00FF00FF00FF)) << 8);
	value = ((value & W64LIT(0xFFFF0000FFFF0000)) >> 16) |
            ((value & W64LIT(0x0000FFFF0000FFFF)) << 16);
	return rotlFixed64(value, 32U);
#endif
}


STATIC INLINE void ByteReverseWords64(word64* out, const word64* in,
                                      word32 byteCount)
{
    word32 count = byteCount/(word32)sizeof(word64), i;

    for (i = 0; i < count; i++)
        out[i] = ByteReverseWord64(in[i]);

}

#endif /* WORD64_AVAILABLE */


STATIC INLINE void XorWords(wolfssl_word* r, const wolfssl_word* a, word32 n)
{
    word32 i;

    for (i = 0; i < n; i++) r[i] ^= a[i];
}


STATIC INLINE void xorbuf(void* buf, const void* mask, word32 count)
{
    if (((wolfssl_word)buf | (wolfssl_word)mask | count) % WOLFSSL_WORD_SIZE == 0)
        XorWords( (wolfssl_word*)buf,
                  (const wolfssl_word*)mask, count / WOLFSSL_WORD_SIZE);
    else {
        word32 i;
        byte*       b = (byte*)buf;
        const byte* m = (const byte*)mask;

        for (i = 0; i < count; i++) b[i] ^= m[i];
    }
}


/* Make sure compiler doesn't skip */
STATIC INLINE void ForceZero(const void* mem, word32 len)
{
    volatile byte* z = (volatile byte*)mem;

    while (len--) *z++ = 0;
}


/* check all length bytes for equality, return 0 on success */
STATIC INLINE int ConstantCompare(const byte* a, const byte* b, int length)
{
    int i;
    int compareSum = 0;

    for (i = 0; i < length; i++) {
        compareSum |= a[i] ^ b[i];
    }

    return compareSum;
}

#undef STATIC

#endif /* WOLF_CRYPT_MISC_C */