blob.c

gif图像文件软件解码器的arm版本的源代码程序

///////////////////////////////////////////////////////////////////////////////
//
//  blob.c
//
//  DESCRIPTION
//        Define functions to read binary data
//
//
///////////////////////////////////////////////////////////////////////////////


/*
  Include declarations.
*/

#include "gifcommon.h"

/*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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%   G e t B l o b I n f o                                                     %
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%
%  GetBlobInfo() initializes the BlobInfo structure.
%
%  The format of the GetBlobInfo method is:
%
%      void GetBlobInfo(BlobInfo *blob_info)
%
%  A description of each parameter follows:
%
%    o blob_info: Specifies a pointer to a BlobInfo structure.
%
%
*/
void GetBlobInfo
(
    BlobInfo    *blob_info
)
{
    (void) memset(blob_info, 0, sizeof(BlobInfo));
    blob_info->quantum = 65536;
}

/*
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%                                                                             %
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%   C l o n e B l o b I n f o                                                 %
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%  Method CloneBlobInfo makes a duplicate of the given blob info structure,
%  or if blob info is NULL, a new one.
%
%  The format of the CloneBlobInfo method is:
%
%      BlobInfo *CloneBlobInfo(const BlobInfo *blob_info)
%
%  A description of each parameter follows:
%
%    o clone_info: Method CloneBlobInfo returns a duplicate of the given
%      blob info, or if blob info is NULL a new one.
%
%    o quantize_info: a structure of type info.
%
%
*/
BlobInfo *CloneBlobInfo
(
    const BlobInfo      *blob_info, 
    AllocateMemory      getmemory
)
{
    BlobInfo    *clone_info;

    clone_info = (BlobInfo *) getmemory(sizeof(BlobInfo));
    
    if (clone_info == (BlobInfo *) OP_NULL)
    {
        return OP_NULL;
    }
    if (blob_info == (BlobInfo *) OP_NULL)
    {
        GetBlobInfo(clone_info);
        return(clone_info);
    }
    *clone_info=(*blob_info);
    
    return(clone_info);
}

/*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                                                                             %
%                                                                             %
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+   O p e n B l o b                                                           %
%                                                                             %
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%  Method OpenBlob opens a file associated with the image.  A file name of
%  '-' sets the file to stdin for type 'r' and stdout for type 'w'.  If the
%  filename suffix is '.gz' or '.Z', the image is decompressed for type 'r'
%  and compressed for type 'w'.  If the filename prefix is '|', it is piped
%  to or from a system command.
%
%  The format of the OpenBlob method is:
%
%      unsigned int OpenBlob(const ImageInfo *image_info,Image *image,
%        const char *type,ExceptionInfo *exception)
%
%  A description of each parameter follows:
%
%    o status:  Method OpenBlob returns True if the file is successfully
%      opened otherwise False.
%
%    o image_info: The image info..
%
%    o image: The image.
%
%    o type: 'r' for reading; 'w' for writing.
%
*/
unsigned int OpenBlob
(
    Image           *image, 
    const char      *type
)
{
    return 1;
}

 /*
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%                                                                             %
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+   C l o s e B l o b                                                         %
%                                                                             %
%                                                                             %
%                                                                             %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%  Method CloseBlob closes a file associated with the image.  If the
%  filename prefix is '|', the file is a pipe and is closed with PipeClose.
%
%  The format of the CloseBlob method is:
%
%      void CloseBlob(Image *image)
%
%  A description of each parameter follows:
%
%    o image: The image.
%
%
*/
void CloseBlob
(
    Image   *image
)
{
}

/*
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%   D e s t r o y B l o b I n f o                                             %
%                                                                             %
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%                                                                             %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%  DestroyBlobInfo() deallocates memory associated with an BlobInfo structure.
%
%  The format of the DestroyBlobInfo method is:
%
%      void DestroyBlobInfo(BlobInfo *blob)
%
%  A description of each parameter follows:
%
%    o blob: Specifies a pointer to a BlobInfo structure.
%
%
*/
void DestroyBlobInfo
(
    BlobInfo            *blob, 
    LiberateMemory      freememory
)
{
    freememory((void *) blob);
}

/*
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                                                                             %
%                                                                             %
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+  R e a d B l o b                                                            %
%                                                                             %
%                                                                             %
%                                                                             %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%  Method ReadBlob reads data from the blob or image file and returns it.  It
%  returns the number of bytes read.
%
%  The format of the ReadBlob method is:
%
%      unsigned int ReadBlob(Image *image,const unsigned int length,void *data)
%
%  A description of each parameter follows:
%
%    o count:  Method ReadBlob returns the number of bytes read.
%
%    o image: The image.
%
%    o length:  Specifies an integer representing the number of bytes
%      to read from the file.
%
%    o data:  Specifies an area to place the information requested from
%      the file.
%
%
*/
unsigned int ReadBlob
(
    Image               *image,
    const unsigned int  length,
    unsigned char       **data
)
{
    unsigned int count;

    count=Min(length,image->blob->length-image->blob->offset);
    if(count != 0)
    {
        *data = image->blob->data+image->blob->offset;
        image->blob->offset+=count;
    }
    return(count);
}

/*
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+  R e a d B l o b B y t e                                                    %
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%  Method ReadBlobByte reads a single byte from the image file and returns it.
%
%  The format of the ReadBlobByte method is:
%
%      int ReadBlobByte(Image *image)
%
%  A description of each parameter follows.
%
%    o value: Method ReadBlobByte returns an integer read from the file.
%
%    o image: The image.
%
%
*/
int ReadBlobByte
(
    Image   *image
)
{
    unsigned char     *tp;
    unsigned char     **p;
    unsigned int      count;

    p = &tp;

    count = ReadBlob(image, 1, p);
    if (count == 0)
    {
        return(EOF);
    }
    return(*tp);
}
/*
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%                                                                             %
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+  R e a d B l o b L S B S h o r t                                            %
%                                                                             %
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%                                                                             %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
%  Method ReadBlobLSBShort reads a short value as a 16 bit quantity in
%  least-significant byte first order.
%
%  The format of the ReadBlobLSBShort method is:
%
%      unsigned short ReadBlobLSBShort(Image *image)
%
%  A description of each parameter follows.
%
%    o value:  Method ReadBlobLSBShort returns an unsigned short read from
%      the file.
%
%    o image: The image.
%
%
*/
unsigned short ReadBlobLSBShort
(
    Image   *image
)
{
    unsigned char       *tp;
    unsigned char       **p;

    unsigned short      value;

    p = &tp;

    value = ReadBlob(image, 2, p);
    if (value == 0)
    {
        return((unsigned short) ~0);
    }
    value = tp[1] << 8;
    value |= tp[0];
    return(value);
}