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DEFINITIONS
This source file includes following definitions.
- av_log2
- av_log2_16bit
- av_clip
- av_clip_uint8
- av_clip_int16
- av_clipf
/*
* copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
*
* 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
*/
/**
* @file libavutil/common.h
* common internal and external API header
*/
#ifndef AVUTIL_COMMON_H
#define AVUTIL_COMMON_H
#include <ctype.h>
#include <errno.h>
#include <inttypes.h>
#include <limits.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#ifdef __GNUC__
# define AV_GCC_VERSION_AT_LEAST(x,y) (__GNUC__ > x || __GNUC__ == x && __GNUC_MINOR__ >= y)
#else
# define AV_GCC_VERSION_AT_LEAST(x,y) 0
#endif
#ifndef av_always_inline
#if AV_GCC_VERSION_AT_LEAST(3,1)
# define av_always_inline __attribute__((always_inline)) inline
#else
# define av_always_inline inline
#endif
#endif
#ifndef av_noinline
#if AV_GCC_VERSION_AT_LEAST(3,1)
# define av_noinline __attribute__((noinline))
#else
# define av_noinline
#endif
#endif
#ifndef av_pure
#if AV_GCC_VERSION_AT_LEAST(3,1)
# define av_pure __attribute__((pure))
#else
# define av_pure
#endif
#endif
#ifndef av_const
#if AV_GCC_VERSION_AT_LEAST(2,6)
# define av_const __attribute__((const))
#else
# define av_const
#endif
#endif
#ifndef av_cold
#if (!defined(__ICC) || __ICC > 1100) && AV_GCC_VERSION_AT_LEAST(4,3)
# define av_cold __attribute__((cold))
#else
# define av_cold
#endif
#endif
#ifndef av_flatten
#if AV_GCC_VERSION_AT_LEAST(4,1)
# define av_flatten __attribute__((flatten))
#else
# define av_flatten
#endif
#endif
#ifndef attribute_deprecated
#if AV_GCC_VERSION_AT_LEAST(3,1)
# define attribute_deprecated __attribute__((deprecated))
#else
# define attribute_deprecated
#endif
#endif
#ifndef av_unused
#if defined(__GNUC__)
# define av_unused __attribute__((unused))
#else
# define av_unused
#endif
#endif
#ifndef av_uninit
#if defined(__GNUC__) && !defined(__ICC)
# define av_uninit(x) x=x
#else
# define av_uninit(x) x
#endif
#endif
//rounded division & shift
#define RSHIFT(a,b) ((a) > 0 ? ((a) + ((1<<(b))>>1))>>(b) : ((a) + ((1<<(b))>>1)-1)>>(b))
/* assume b>0 */
#define ROUNDED_DIV(a,b) (((a)>0 ? (a) + ((b)>>1) : (a) - ((b)>>1))/(b))
#define FFABS(a) ((a) >= 0 ? (a) : (-(a)))
#define FFSIGN(a) ((a) > 0 ? 1 : -1)
#define FFMAX(a,b) ((a) > (b) ? (a) : (b))
#define FFMAX3(a,b,c) FFMAX(FFMAX(a,b),c)
#define FFMIN(a,b) ((a) > (b) ? (b) : (a))
#define FFMIN3(a,b,c) FFMIN(FFMIN(a,b),c)
#define FFSWAP(type,a,b) do{type SWAP_tmp= b; b= a; a= SWAP_tmp;}while(0)
#define FF_ARRAY_ELEMS(a) (sizeof(a) / sizeof((a)[0]))
/* misc math functions */
extern const uint8_t ff_log2_tab[256];
static inline av_const int av_log2(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;
}
static inline av_const int av_log2_16bit(unsigned int v)
{
int n = 0;
if (v & 0xff00) {
v >>= 8;
n += 8;
}
n += ff_log2_tab[v];
return n;
}
/**
* Clips a signed integer value into the amin-amax range.
* @param a value to clip
* @param amin minimum value of the clip range
* @param amax maximum value of the clip range
* @return clipped value
*/
static inline av_const int av_clip(int a, int amin, int amax)
{
if (a < amin) return amin;
else if (a > amax) return amax;
else return a;
}
/**
* Clips a signed integer value into the 0-255 range.
* @param a value to clip
* @return clipped value
*/
static inline av_const uint8_t av_clip_uint8(int a)
{
if (a&(~255)) return (-a)>>31;
else return a;
}
/**
* Clips a signed integer value into the -32768,32767 range.
* @param a value to clip
* @return clipped value
*/
static inline av_const int16_t av_clip_int16(int a)
{
if ((a+32768) & ~65535) return (a>>31) ^ 32767;
else return a;
}
/**
* Clips a float value into the amin-amax range.
* @param a value to clip
* @param amin minimum value of the clip range
* @param amax maximum value of the clip range
* @return clipped value
*/
static inline av_const float av_clipf(float a, float amin, float amax)
{
if (a < amin) return amin;
else if (a > amax) return amax;
else return a;
}
#define MKTAG(a,b,c,d) (a | (b << 8) | (c << 16) | (d << 24))
#define MKBETAG(a,b,c,d) (d | (c << 8) | (b << 16) | (a << 24))
/*!
* \def GET_UTF8(val, GET_BYTE, ERROR)
* Converts a UTF-8 character (up to 4 bytes long) to its 32-bit UCS-4 encoded form
* \param val is the output and should be of type uint32_t. It holds the converted
* UCS-4 character and should be a left value.
* \param GET_BYTE gets UTF-8 encoded bytes from any proper source. It can be
* a function or a statement whose return value or evaluated value is of type
* uint8_t. It will be executed up to 4 times for values in the valid UTF-8 range,
* and up to 7 times in the general case.
* \param ERROR action that should be taken when an invalid UTF-8 byte is returned
* from GET_BYTE. It should be a statement that jumps out of the macro,
* like exit(), goto, return, break, or continue.
*/
#define GET_UTF8(val, GET_BYTE, ERROR)\
val= GET_BYTE;\
{\
int ones= 7 - av_log2(val ^ 255);\
if(ones==1)\
ERROR\
val&= 127>>ones;\
while(--ones > 0){\
int tmp= GET_BYTE - 128;\
if(tmp>>6)\
ERROR\
val= (val<<6) + tmp;\
}\
}
/*!
* \def PUT_UTF8(val, tmp, PUT_BYTE)
* Converts a 32-bit Unicode character to its UTF-8 encoded form (up to 4 bytes long).
* \param val is an input-only argument and should be of type uint32_t. It holds
* a UCS-4 encoded Unicode character that is to be converted to UTF-8. If
* val is given as a function it is executed only once.
* \param tmp is a temporary variable and should be of type uint8_t. It
* represents an intermediate value during conversion that is to be
* output by PUT_BYTE.
* \param PUT_BYTE writes the converted UTF-8 bytes to any proper destination.
* It could be a function or a statement, and uses tmp as the input byte.
* For example, PUT_BYTE could be "*output++ = tmp;" PUT_BYTE will be
* executed up to 4 times for values in the valid UTF-8 range and up to
* 7 times in the general case, depending on the length of the converted
* Unicode character.
*/
#define PUT_UTF8(val, tmp, PUT_BYTE)\
{\
int bytes, shift;\
uint32_t in = val;\
if (in < 0x80) {\
tmp = in;\
PUT_BYTE\
} else {\
bytes = (av_log2(in) + 4) / 5;\
shift = (bytes - 1) * 6;\
tmp = (256 - (256 >> bytes)) | (in >> shift);\
PUT_BYTE\
while (shift >= 6) {\
shift -= 6;\
tmp = 0x80 | ((in >> shift) & 0x3f);\
PUT_BYTE\
}\
}\
}
#include "mem.h"
#ifdef HAVE_AV_CONFIG_H
# include "config.h"
# include "internal.h"
#endif /* HAVE_AV_CONFIG_H */
#endif /* AVUTIL_COMMON_H */