/*
  * Copyright (c) 2010 Mans Rullgard <mans@mansr.com>
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg 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.
  *
  * FFmpeg 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 FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 #ifndef AVUTIL_INTMATH_H
 #define AVUTIL_INTMATH_H
 

 #include <stdint.h>
 

 #include "config.h"

 #include "attributes.h"

 #if ARCH_ARM
 #   include "arm/intmath.h"
 #endif

 #if ARCH_X86
 #   include "x86/intmath.h"
 #endif

 #if HAVE_FAST_CLZ

 #if AV_GCC_VERSION_AT_LEAST(3,4)

 #ifndef ff_log2

 #   define ff_log2(x) (31 - __builtin_clz((x)|1))

 #   ifndef ff_log2_16bit
 #      define ff_log2_16bit av_log2
 #   endif
 #endif /* ff_log2 */

 #endif /* AV_GCC_VERSION_AT_LEAST(3,4) */

 #endif

 extern const uint8_t ff_log2_tab[256];
 
 #ifndef ff_log2
 #define ff_log2 ff_log2_c
 static av_always_inline av_const int ff_log2_c(unsigned int v)
 {
     int n = 0;
     if (v & 0xffff0000) {
         v >>= 16;
         n += 16;
     }
     if (v & 0xff00) {
         v >>= 8;
         n += 8;
     }
     n += ff_log2_tab[v];
 
     return n;
 }
 #endif
 
 #ifndef ff_log2_16bit
 #define ff_log2_16bit ff_log2_16bit_c
 static av_always_inline av_const int ff_log2_16bit_c(unsigned int v)
 {
     int n = 0;
     if (v & 0xff00) {
         v >>= 8;
         n += 8;
     }
     n += ff_log2_tab[v];
 
     return n;
 }
 #endif
 
 #define av_log2       ff_log2
 #define av_log2_16bit ff_log2_16bit
 

 /**

  * @addtogroup lavu_math
  * @{
  */
 

 #if HAVE_FAST_CLZ

 #if AV_GCC_VERSION_AT_LEAST(3,4)

 #ifndef ff_ctz

 #define ff_ctz(v) __builtin_ctz(v)

 #endif

 #ifndef ff_ctzll
 #define ff_ctzll(v) __builtin_ctzll(v)
 #endif

 #ifndef ff_clz
 #define ff_clz(v) __builtin_clz(v)
 #endif

 #endif

 #endif
 
 #ifndef ff_ctz
 #define ff_ctz ff_ctz_c

 /**
  * Trailing zero bit count.
  *
  * @param v  input value. If v is 0, the result is undefined.
  * @return   the number of trailing 0-bits
  */

 /* We use the De-Bruijn method outlined in:
  * http://supertech.csail.mit.edu/papers/debruijn.pdf. */

 static av_always_inline av_const int ff_ctz_c(int v)
 {

     static const uint8_t debruijn_ctz32[32] = {
         0, 1, 28, 2, 29, 14, 24, 3, 30, 22, 20, 15, 25, 17, 4, 8,
         31, 27, 13, 23, 21, 19, 16, 7, 26, 12, 18, 6, 11, 5, 10, 9
     };
     return debruijn_ctz32[(uint32_t)((v & -v) * 0x077CB531U) >> 27];

 }
 #endif
 

 #ifndef ff_ctzll
 #define ff_ctzll ff_ctzll_c
 /* We use the De-Bruijn method outlined in:
  * http://supertech.csail.mit.edu/papers/debruijn.pdf. */
 static av_always_inline av_const int ff_ctzll_c(long long v)
 {

     static const uint8_t debruijn_ctz64[64] = {

         0, 1, 2, 53, 3, 7, 54, 27, 4, 38, 41, 8, 34, 55, 48, 28,
         62, 5, 39, 46, 44, 42, 22, 9, 24, 35, 59, 56, 49, 18, 29, 11,
         63, 52, 6, 26, 37, 40, 33, 47, 61, 45, 43, 21, 23, 58, 17, 10,
         51, 25, 36, 32, 60, 20, 57, 16, 50, 31, 19, 15, 30, 14, 13, 12
     };

     return debruijn_ctz64[(uint64_t)((v & -v) * 0x022FDD63CC95386DU) >> 58];

 }
 #endif
 

 #ifndef ff_clz
 #define ff_clz ff_clz_c
 static av_always_inline av_const unsigned ff_clz_c(unsigned x)
 {
     unsigned i = sizeof(x) * 8;
 
     while (x) {
         x >>= 1;
         i--;
     }
 
     return i;
 }
 #endif
 

 #if AV_GCC_VERSION_AT_LEAST(3,4)
 #ifndef av_parity
 #define av_parity __builtin_parity

 #endif
 #endif
 

 /**
  * @}
  */

 #endif /* AVUTIL_INTMATH_H */