common.h

播放H264文件的播放器

/*
 * copyright (c) 2006 Michael Niedermayer <[e-mail]>
 *
 * 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 <limits.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef signed char  int8_t;
typedef signed short int16_t;
typedef signed int   int32_t;
typedef unsigned char  uint8_t;
typedef unsigned short uint16_t;
typedef unsigned int   uint32_t;

typedef signed __int64   int64_t;
typedef unsigned __int64 uint64_t;

#define ABS(a) ((a) >= 0 ? (a) : (-(a)))

#define FFMAX(a,b) ((a) > (b) ? (a) : (b))
#define FFMIN(a,b) ((a) > (b) ? (b) : (a))

#define FASTDIV(a,b)   ((a)/(b))

#define NEG_SSR32(a,s) ((( int32_t)(a))>>(32-(s)))
#define NEG_USR32(a,s) (((uint32_t)(a))>>(32-(s)))

#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 "internal.h"
#endif /* HAVE_AV_CONFIG_H */

#endif /* AVUTIL_COMMON_H */