.. _afterburner:

afterburner
===========

Description
'''''''''''

|  Synthesizes to 47 slices and 1 MULT18X18 at 166 MHz in XC3Sxxx-4 using XST-9.2.04i
|   Use parameter triple instead of preprocessor variable AFTERBURNER_TRIPLE
|   User port coeff instead of parameter coeff
|  If the port coeff is set to a constant value, should synthesize identically
|  There is a latency of 3 clock cycles (??)
|  Note: The output of the module is Offset Binary
|  [It is perhaps stupid to have that here and it should be moved into another module]
| 
|  CONCEPT: The mid point along the circle of a of 2 complex numbers that already lie
|           on a circle is not a plain average. To obtain the (real/imaginary) component
|           of this mid-point one has to multiply by what is called "coeff"
|           k = 0.5*sec(theta) .. where theta is the angle between the complex numbers
| 

Pinout
''''''

.. _fig:afterburner_block:
.. figure:: afterburner_block.png
    :alt: Schematic symbol

Parameters
''''''''''

.. list-table:: afterburner_param_table
   :header-rows: 1

   * - Name
     - Min
     - Max
     - Default
     - Description
   * - triple
     - ?
     - ?
     - 0
     - 

Ports
'''''

.. list-table:: afterburner_port_table
   :header-rows: 1

   * - Signal
     - Direction
     - Description
   * - clk
     - Input
     - timespec 6.0 ns
   * - data[16:0]
     - Input
     - This is level set data [.. a_n1, a_n2 ..]
   * - coeff[15:0]
     - Input
     - Coefficient to correct for  interpolation
   * - data_out0[15:0]
     - Output
     - Interpolated [coeff*[..(a_n1+a_n2), (a_n2+a_n3),..]]
   * - data_out1[15:0]
     - Output
     - Untouched    [.. a_n1, a_n2 ..]

Implementation and use
''''''''''''''''''''''

The `portable`_ `Verilog`_
implementation can be found in :ref:`afterburner_source`

.. _`portable`: https://en.wikipedia.org/wiki/Software_portability
.. _`Verilog`: https://en.wikipedia.org/wiki/Verilog

Timing Diagram
''''''''''''''

A `GTKWave`_-generated timing diagram is shown below:

.. _`GTKWave`: https://gtkwave.sourceforge.net/

.. _fig:afterburner_timing:
.. figure:: afterburner_timing.png
    :alt: Timing diagram