1/*
2 *  Copyright (c) 2010 The WebM project authors. All Rights Reserved.
3 *
4 *  Use of this source code is governed by a BSD-style license
5 *  that can be found in the LICENSE file in the root of the source
6 *  tree. An additional intellectual property rights grant can be found
7 *  in the file PATENTS.  All contributing project authors may
8 *  be found in the AUTHORS file in the root of the source tree.
9 */
10
11#ifndef VP9_COMMON_VP9_SYSTEMDEPENDENT_H_
12#define VP9_COMMON_VP9_SYSTEMDEPENDENT_H_
13
14#ifdef _MSC_VER
15# include <math.h>  // the ceil() definition must precede intrin.h
16# if _MSC_VER > 1310 && (defined(_M_X64) || defined(_M_IX86))
17#  include <intrin.h>
18#  define USE_MSC_INTRIN
19# endif
20# define snprintf _snprintf
21#endif
22
23#ifdef __cplusplus
24extern "C" {
25#endif
26
27#include "./vpx_config.h"
28#if ARCH_X86 || ARCH_X86_64
29void vpx_reset_mmx_state(void);
30#define vp9_clear_system_state() vpx_reset_mmx_state()
31#else
32#define vp9_clear_system_state()
33#endif
34
35#if defined(_MSC_VER) && _MSC_VER < 1800
36// round is not defined in MSVC before VS2013.
37static INLINE int round(double x) {
38  if (x < 0)
39    return (int)ceil(x - 0.5);
40  else
41    return (int)floor(x + 0.5);
42}
43#endif
44
45// use GNU builtins where available.
46#if defined(__GNUC__) && \
47    ((__GNUC__ == 3 && __GNUC_MINOR__ >= 4) || __GNUC__ >= 4)
48static INLINE int get_msb(unsigned int n) {
49  return 31 ^ __builtin_clz(n);
50}
51#elif defined(USE_MSC_INTRIN)
52#pragma intrinsic(_BitScanReverse)
53
54static INLINE int get_msb(unsigned int n) {
55  unsigned long first_set_bit;
56  _BitScanReverse(&first_set_bit, n);
57  return first_set_bit;
58}
59#undef USE_MSC_INTRIN
60#else
61// Returns (int)floor(log2(n)). n must be > 0.
62static INLINE int get_msb(unsigned int n) {
63  int log = 0;
64  unsigned int value = n;
65  int i;
66
67  for (i = 4; i >= 0; --i) {
68    const int shift = (1 << i);
69    const unsigned int x = value >> shift;
70    if (x != 0) {
71      value = x;
72      log += shift;
73    }
74  }
75  return log;
76}
77#endif
78
79#ifdef __cplusplus
80}  // extern "C"
81#endif
82
83#endif  // VP9_COMMON_VP9_SYSTEMDEPENDENT_H_
84