ftstream.c

Qt/Embedded是一个多平台的C++图形用户界面应用程序框架

#include <ftstream.h>
#include <ftdebug.h>

#undef  FT_COMPONENT
#define FT_COMPONENT  trace_stream


  BASE_FUNC
  void  FT_New_Memory_Stream( FT_Library     library,
                              void*          base,
                              unsigned long  size,
                              FT_Stream      stream )
  {
    stream->memory = library->memory;
    stream->base   = (char*)base;
    stream->size   = size;
    stream->pos    = 0;
    stream->cursor = 0;
    stream->read   = 0;
    stream->close  = 0;
  }


  BASE_FUNC
  FT_Error  FT_Seek_Stream( FT_Stream  stream,
                            FT_ULong   pos )
  {
    FT_Error  error;

    stream->pos = pos;

    if (stream->read)
    {
      if (stream->read( stream, pos, 0, 0 ))
      {
        error = FT_Err_Invalid_Stream_Operation;

        FT_ERROR(( "FT_Seek_Stream:" ));
        FT_ERROR(( " invalid i/o, pos = 0x%lx, size = 0x%lx\n",
                   pos, stream->size ));
      }
      else
        error = FT_Err_Ok;
    }
    /* note that seeking to the first position after the file is valid */
    else if (pos > stream->size)
    {
      error = FT_Err_Invalid_Stream_Operation;

      FT_ERROR(( "FT_Seek_Stream:" ));
      FT_ERROR(( " invalid i/o, pos = 0x%lx, size = 0x%lx\n",
                 pos, stream->size ));
    }

    else
      error = FT_Err_Ok;

    return error;
  }


  BASE_FUNC
  FT_Error  FT_Skip_Stream( FT_Stream  stream,
                            FT_Long    distance )
  {
    return FT_Seek_Stream( stream, (FT_ULong)(stream->pos + distance) );
  }



  BASE_FUNC
  FT_Long   FT_Stream_Pos( FT_Stream  stream )
  {
    return stream->pos;
  }


  BASE_FUNC
  FT_Error  FT_Read_Stream( FT_Stream  stream,
                            void*      buffer,
                            FT_ULong   count )
  {
    return FT_Read_Stream_At( stream, stream->pos, buffer, count );
  }


  BASE_FUNC
  FT_Error  FT_Read_Stream_At( FT_Stream  stream,
                               FT_ULong   pos,
                               void*      buffer,
                               FT_ULong   count )
  {
    FT_Error  error = FT_Err_Ok;
    FT_ULong  read_bytes;

    if (pos >= stream->size)
    {
      FT_ERROR(( "FT_Read_Stream_At:" ));
      FT_ERROR(( " invalid i/o, pos = 0x%lx, size = 0x%lx\n",
                 pos, stream->size ));

      return FT_Err_Invalid_Stream_Operation;
    }

    if (stream->read)
      read_bytes = stream->read( stream, pos, buffer, count );
    else
    {
      read_bytes = stream->size - pos;
      if (read_bytes > count)
        read_bytes = count;

      MEM_Copy( buffer, stream->base + pos, read_bytes );
    }

    stream->pos = pos + read_bytes;

    if (read_bytes < count)
    {
      FT_ERROR(( "FT_Read_Stream_At:" ));
      FT_ERROR(( " invalid read, expected %lu bytes, got %lu",
                 count, read_bytes ));
      error = FT_Err_Invalid_Stream_Operation;
    }

    return error;
  }



  BASE_FUNC
  FT_Error  FT_Access_Frame( FT_Stream  stream,
                             FT_ULong   count )
  {
    FT_Error  error = FT_Err_Ok;
    FT_ULong  read_bytes;

    /* check for nested frame access */
    FT_Assert( stream && stream->cursor == 0 );

    if (stream->read)
    {
      /* allocate the frame in memory */
      FT_Memory  memory = stream->memory;

      if ( ALLOC( stream->base, count ) )
        goto Exit;

      /* read it */
      read_bytes = stream->read( stream, stream->pos,
                                 stream->base, count );
      if (read_bytes < count)
      {
        FT_ERROR(( "FT_Access_Frame:" ));
        FT_ERROR(( " invalid read, expected %lu bytes, got %lu",
                   count, read_bytes ));

        FREE( stream->base );
        error = FT_Err_Invalid_Stream_Operation;
      }
      stream->cursor = stream->base;
      stream->limit  = stream->cursor + count;
      stream->pos   += read_bytes;
    }
    else
    {
      /* check current and new position */
      if (stream->pos >= stream->size || stream->pos + count > stream->size)
      {
        FT_ERROR(( "FT_Access_Frame:" ));
        FT_ERROR(( " invalid i/o, pos = 0x%lx, count = %lu, size = 0x%lx",
                   stream->pos, count, stream->size ));

        error = FT_Err_Invalid_Stream_Operation;
        goto Exit;
      }

      /* set cursor */
      stream->cursor = stream->base + stream->pos;
      stream->limit  = stream->cursor + count;
      stream->pos   += count;
    }
  Exit:
    return error;
  }


  BASE_FUNC
  void  FT_Forget_Frame( FT_Stream  stream )
  {
    FT_Assert( stream && stream->cursor != 0 );

    if (stream->read)
    {
      FT_Memory  memory = stream->memory;

      FREE( stream->base );
    }
    stream->cursor = 0;
    stream->limit  = 0;
  }


  BASE_FUNC
  FT_Char  FT_Get_Char( FT_Stream  stream )
  {
    FT_Char  result;

    FT_Assert( stream && stream->cursor && stream->cursor );

    result = 0;
    if (stream->cursor < stream->limit)
      result = *stream->cursor++;

    return result;
  }


  BASE_FUNC
  FT_Short  FT_Get_Short( FT_Stream  stream )
  {
    char*     p;
    FT_Short  result;

    FT_Assert( stream && stream->cursor );

    result         = 0;
    p              = stream->cursor;
    if (p+1 < stream->limit)
      result       = NEXT_Short(p);
    stream->cursor = p;
    return result;
  }


  BASE_FUNC
  FT_Long  FT_Get_Offset( FT_Stream  stream )
  {
    char*    p;
    FT_Long  result;

    FT_Assert( stream && stream->cursor );

    result         = 0;
    p              = stream->cursor;
    if (p+2 < stream->limit)
      result       = NEXT_Offset(p);
    stream->cursor = p;
    return result;
  }


  BASE_FUNC
  FT_Long  FT_Get_Long( FT_Stream  stream )
  {
    char*    p;
    FT_Long  result;

    FT_Assert( stream && stream->cursor );

    result         = 0;
    p              = stream->cursor;
    if (p+3 < stream->limit)
      result       = NEXT_Long(p);
    stream->cursor = p;
    return result;
  }


  BASE_FUNC
  FT_Char  FT_Read_Char( FT_Stream  stream,
                         FT_Error*  error )
  {
    char  result = 0;

    FT_Assert( stream );

    *error = FT_Err_Ok;

    if (stream->read)
    {
      if ( stream->read( stream, stream->pos, &result, 1L ) != 1L )
        goto Fail;
    }
    else
    {
      if (stream->pos < stream->size)
        result = stream->base[stream->pos];
      else
        goto Fail;
    }
    stream->pos++;
    return result;

  Fail:
    *error = FT_Err_Invalid_Stream_Operation;
    FT_ERROR(( "FT_Read_Char:" ));
    FT_ERROR(( " invalid i/o, pos = 0x%lx, size = 0x%lx",
               stream->pos, stream->size ));
    return 0;
  }


  BASE_FUNC
  FT_Short  FT_Read_Short( FT_Stream  stream,
                           FT_Error*  error )
  {
    char     reads[2];
    char*    p = 0;
    FT_Short result = 0;

    FT_Assert( stream );

    *error = FT_Err_Ok;

    if (stream->pos+1 < stream->size)
    {
      if (stream->read)
      {
        if (stream->read( stream, stream->pos, reads, 2L ) != 2L )
          goto Fail;

        p = reads;
      }
      else
      {
        p = stream->base + stream->pos;
      }

      if (p)
        result = NEXT_Short(p);
    }
    else goto Fail;

    stream->pos += 2;
    return result;

  Fail:
    *error = FT_Err_Invalid_Stream_Operation;
    FT_ERROR(( "FT_Read_Short:" ));
    FT_ERROR(( " invalid i/o, pos = 0x%lx, size = 0x%lx",
               stream->pos, stream->size ));
    return 0;
  }


  BASE_FUNC
  FT_Long  FT_Read_Offset( FT_Stream  stream,
                           FT_Error*  error )
  {
    char     reads[3];
    char*    p = 0;
    FT_Long  result = 0;

    FT_Assert( stream );

    *error = FT_Err_Ok;

    if (stream->pos+2 < stream->size)
    {
      if (stream->read)
      {
        if (stream->read( stream, stream->pos, reads, 3L ) != 3L )
          goto Fail;

        p = reads;
      }
      else
      {
        p = stream->base + stream->pos;
      }

      if (p)
        result = NEXT_Offset(p);
    }
    else goto Fail;

    stream->pos += 3;
    return result;

  Fail:
    *error = FT_Err_Invalid_Stream_Operation;
    FT_ERROR(( "FT_Read_Offset:" ));
    FT_ERROR(( " invalid i/o, pos = 0x%lx, size = 0x%lx",
               stream->pos, stream->size ));
    return 0;
  }


  BASE_FUNC
  FT_Long  FT_Read_Long( FT_Stream  stream,
                         FT_Error*  error )
  {
    char     reads[4];
    char*    p = 0;
    FT_Long  result = 0;

    FT_Assert( stream );

    *error = FT_Err_Ok;

    if (stream->pos+3 < stream->size)
    {
      if (stream->read)
      {
        if (stream->read( stream, stream->pos, reads, 4L ) != 4L )
          goto Fail;

        p = reads;
      }
      else
      {
        p = stream->base + stream->pos;
      }

      if (p)
        result = NEXT_Long(p);
    }
    else goto Fail;

    stream->pos += 4;
    return result;

  Fail:
    *error = FT_Err_Invalid_Stream_Operation;
    FT_ERROR(( "FT_Read_Long:" ));
    FT_ERROR(( " invalid i/o, pos = 0x%lx, size = 0x%lx",
               stream->pos, stream->size ));
    return 0;
  }

  BASE_FUNC
  FT_Error FT_Read_Fields( FT_Stream              stream,
                           const FT_Frame_Field*  fields,
                           void*                  structure )
  {
    FT_Error  error;
    FT_Bool   frame_accessed = 0;
    
    if (!fields || !stream)
      return FT_Err_Invalid_Argument;
      
    error = FT_Err_Ok;
    do
    {
      FT_ULong  value;
      FT_Int    sign_shift;
      FT_Byte*  p;
      
      switch (fields->value)
      {
        case ft_frame_start:  /* access a new frame */
          {
            error = FT_Access_Frame( stream, fields->offset );
            if (error) goto Exit;
            
            frame_accessed = 1;
            fields++;
            continue;  /* loop ! */
          }
          
        case ft_frame_byte:
        case ft_frame_schar:  /* read a single byte */
          {
            value = GET_Byte();
            sign_shift = 24;
            break;
          }
          
        case ft_frame_short_be:
        case ft_frame_ushort_be:  /* read a 2-byte big-endian short */
          {
            value = GET_UShort();
            sign_shift = 16;
            break;
          }

        case ft_frame_short_le:
        case ft_frame_ushort_le:  /* read a 2-byte little-endian short */
          {
            char* p;
            value = 0;
            p     = stream->cursor;
            if (p+1 < stream->limit)
            {
              value = (FT_UShort)p[0] | ((FT_UShort)p[1] << 8);
              stream->cursor += 2;
            }
            sign_shift = 16;
            break;
          }

        case ft_frame_long_be:
        case ft_frame_ulong_be:  /* read a 4-byte big-endian long */
          {
            value = GET_ULong();
            sign_shift = 0;
            break;
          }

        case ft_frame_long_le:
        case ft_frame_ulong_le:  /* read a 4-byte little-endian long */
          {
            char* p;
            value = 0;
            p     = stream->cursor;
            if (p+3 < stream->limit)
            {
              value = (FT_ULong)p[0]        |
                     ((FT_ULong)p[1] << 8)  |
                     ((FT_ULong)p[2] << 16) |
                     ((FT_ULong)p[3] << 24);
              stream->cursor += 4;
            }
            sign_shift = 0;
            break;
          }

        case ft_frame_off3_be:
        case ft_frame_uoff3_be:  /* read a 3-byte big-endian long */
          {
            value = GET_UOffset();
            sign_shift = 8;
            break;
          }

        case ft_frame_off3_le:
        case ft_frame_uoff3_le:  /* read a 3-byte little-endian long */
          {
            char* p;
            value = 0;
            p     = stream->cursor;
            if (p+3 < stream->limit)
            {
              value = (FT_ULong)p[0]        |
                     ((FT_ULong)p[1] << 8)  |
                     ((FT_ULong)p[2] << 16) |
                     ((FT_ULong)p[3] << 24);
              stream->cursor += 4;
            }
            sign_shift = 8;
            break;
          }

        default:
          /* otherwise, exit the loop */
          goto Exit;
      }
      
      /* now, compute the signed value is necessary */
      if (fields->value & FT_FRAME_OP_SIGNED)
        value   = (FT_ULong)((FT_Long)(value << sign_shift) >> sign_shift);
      
      /* finally, store the value in the object */
      
      p = (FT_Byte*)structure + fields->offset;
      switch (fields->size)
      {
        case 1: *(FT_Byte*)p   = (FT_Byte)  value; break;
        case 2: *(FT_UShort*)p = (FT_UShort)value; break;
        case 4: *(FT_ULong*)p  = (FT_ULong) value; break;
        default:  ; /* ignore !! */
      }
      
      /* go to next field */
      fields++;
    }
    while (1);

  Exit:
    /* close the frame if it was opened by this read */
    if (frame_accessed)
      FT_Forget_Frame(stream);
      
    return error;
  }