Pack the pixel information to use less memory. More...

Public Member Functions
	Packing (int noise_w, int pedestal_w, int gain_w, int status_w)
Public Attributes
PackedPixDbType	gain_mask
int	gain_shift
PackedPixDbType	noise_mask
int	noise_shift
int	noise_width
PackedPixDbType	pedestal_mask
int	pedestal_shift
int	pedestal_width
PackedPixDbType	status_mask
int	status_shift
int	status_width

Detailed Description

Pack the pixel information to use less memory.

Definition at line 48 of file SiPixelDbItem.h.

Constructor & Destructor Documentation

SiPixelDbItem::Packing::Packing	(	int	noise_w,
		int	pedestal_w,
		int	gain_w,
		int	status_w
	)

Definition at line 79 of file SiPixelDbItem.cc.

References gather_cfg::cout, gain_mask, gain_shift, noise_mask, noise_shift, pedestal_mask, pedestal_shift, status_mask, and status_shift.

  : noise_width(noise_w), pedestal_width(pedestal_w), status_width(status_w) 
{
  // Constructor: pre-computes masks and shifts from field widths
  // Order of fields (from right to left) is
  // noise, pedestal, gain, status count.
  
  if ( noise_w+pedestal_w+gain_w+status_w != 32) {
    std::cout << std::endl << "Error in SiPixelDbItem::Packing constructor:" 
              << "sum of field widths != 32" << std::endl;
    // TO DO: throw an exception?
  }

  // Fields are counted from right to left!
  
  noise_shift     = 0;
  pedestal_shift  = noise_shift + noise_w;
  gain_shift    = pedestal_shift + pedestal_w;
  status_shift     = gain_shift + gain_w;

  // Ensure the complement of the correct 
  // number of bits:
  PackedPixDbType zero32 = 0;  // 32-bit wide

  noise_mask     = ~(~zero32 << noise_w);
  pedestal_mask  = ~(~zero32 << pedestal_w);
  gain_mask    = ~(~zero32 << gain_w);
  status_mask     = ~(~zero32 << status_w);
}