Predefined wreal Resolution Functions

The following predefined wreal resolution functions can be used to define wreal resolution functions for a discipline:

• default: The default resolution function algorithm for wreal nets that have more than one driver is as follows:

  Conditions	Resolution
  All drivers are driving wrealZState	Drive the receivers using wrealZState
  Exactly one driver is not driving wrealZState	Drive the receivers using the only non- wrealZState value
  More than one driver is not driving wrealZState	Drive the receivers using wrealXState and issue a run-time warning message
  Any driver is driving wrealXState	Drive the receivers using wrealXState

  
  

  
  Here is an example of how the elaborator determines the resolved value of two drivers, wreal1 and wreal2 using the default resolution function.

  wreal1 Value	wreal2 Value	Resolved Value
  wrealZState	wrealZState	wrealZState
  1.23	wrealZState	1.23
  wrealZState	3.33	3.33
  1.23	1.23	wrealXState 1
  1.23	3.33	wrealXState 1
  1.23	wrealXState	wrealXState
  wrealXState	3.33	wrealXState
  wrealXState	wrealZState	wrealXState

  1 If there is more than one non-wrealZState driver, the software issues a run-time warning message.

• fourstate: The fourstate resolution function algorithm for wreal nets that have more than one driver is the same as the Verilog 4-state logic resolution algorithm. It is similar to the default algorithm except that identical drivers resolve to the driven value instead of to wrealXState.

  The fourstate resolution function algorithm is as follows:

  Conditions	Resolution
  All drivers are driving wrealZState	Drive the receivers using wrealZState
  Exactly one driver is not driving wrealZState	Drive the receivers using the only non- wrealZState value
  More than one driver is not driving wrealZState	When all non- wrealZState drivers drive the same value, drive the receivers using that value and issue a run-time warning message When all non- wrealZState driver do not drive the same value, drive the receivers using wrealXState and issue a run-time warning message
  Any driver is drivingwrealXState	Drive the receivers using wrealXState

  Here is an example of how the elaborator determines the resolved value of two drivers, wreal1 and wreal2 using the fourstate resolution function.

  wreal1 Value	wreal2 Value	Resolved Value
  wrealZState	wrealZState	wrealZState
  1.23	wrealZState	1.23
  wrealZState	3.33	3.33
  1.23	1.23	1.23
  1.23	3.33	wrealXState 1
  1.23	wrealXState	wrealXState
  wrealXState	3.33	wrealXState
  wrealXState	wrealZState	wrealXState

  1 If there is more than one non-wrealZState driver, the software issues a run-time warning message.

• sum: The sum resolution function algorithm for wreal nets that have more than one driver resolves to the summation of all the drivers, ignoring wrealZState drivers. If any drivers are driving wrealXState, the elaborator resolves the value to wrealXState. Any nets driving wrealZState do not contribute to the resolved value.

  The sum resolution function algorithm forwrealnets that have more than one driver is as follows:

  Conditions	Resolution
  All drivers are driving wrealZState	Drive the receivers using wrealZState
  Any driver is driving wrealZState	Drive the receivers with the summation of all non- wrealZState values (that is, ignore all wrealZState drivers)
  No driver is driving wrealZState	Drive the receivers with the summation of all the drivers
  Any driver is driving wrealXState	Drive the receivers using wrealXState

  Here is an example of how the elaborator determines the resolved value of two drivers, wreal1 and wreal2 using the sum resolution function.

  wreal1 Value	wreal2 Value	Resolved Value
  wrealZState	wrealZState	wrealZState
  1.23	wrealZState	1.23
  wrealZState	3.33	3.33
  1.23	1.23	2.46
  1.23	3.33	4.56
  1.23	wrealXState	wrealXState
  wrealXState	3.33	wrealXState
  wrealXState	wrealZState	wrealXState

• avg: The avg resolution function algorithm forwrealnets that have more than one driver is as follows:

  Conditions	Resolution
  All drivers are driving wrealZState	Drive the receivers using wrealZState
  Any driver is driving wrealZState	Drive the receivers with the average of all non- wrealZState values (that is, ignore all wrealZState drivers)
  No driver is driving wrealZState	Drive the receivers with the average of all the drivers
  Any driver is driving wrealXState	Drive the receivers using wrealXState

  Here is an example of how the elaborator determines the resolved value of two drivers, wreal1 and wreal2 using the avg resolution function.

  wreal1 Value	wreal2 Value	Resolved Value
  wrealZState	wrealZState	wrealZState
  1.23	wrealZState	1.23
  wrealZState	3.33	3.33
  1.23	1.23	1.23
  1.23	3.33	2.28
  1.23	wrealXState	wrealXState
  wrealXState	3.33	wrealXState
  wrealXState	wrealZState	wrealXState

• min: The min resolution function algorithm for wreal nets that have more than one driver is as follows:

  Conditions	Resolution
  All drivers are driving wrealZState	Drive the receivers using wrealZState
  Any driver is driving wrealZState	Drive the receivers with the minimum of all non- wrealZState values (that is, ignore all wrealZState drivers)
  No driver is driving wrealZState	Drive the receivers with the minimum of all the drivers
  Any driver is driving wrealXState	Drive the receivers using wrealXState

  Here is an example of how the elaborator determines the resolved value of two drivers, wreal1 and wreal2 using the min resolution function.

  wreal1 Value	wreal2 Value	Resolved Value
  wrealZState	wrealZState	wrealZState
  1.23	wrealZState	1.23
  wrealZState	3.33	3.33
  1.23	1.23	1.23
  1.23	3.33	1.23
  1.23	wrealXState	wrealXState
  wrealXState	3.33	wrealXState
  wrealXState	wrealZState	wrealXState

• max: The max resolution function algorithm for wreal nets that have more than one driver is as follows:

  Conditions	Resolution
  All drivers are driving wrealZState	Drive the receivers using wrealZState
  Any driver is driving wrealZState	Drive the receivers with the maximum of all non- wrealZState values (that is, ignore all wrealZState drivers)
  No driver is driving wrealZState	Drive the receivers with the maximum of all the drivers
  Any driver is driving wrealXState	Drive the receivers using wrealXState

  Here is an example of how the elaborator determines the resolved value of two drivers, wreal1 and wreal2 using the max resolution function.

  wreal1 Value	wreal2 Value	Resolved Value
  wrealZState	wrealZState	wrealZState
  1.23	wrealZState	1.23
  wrealZState	3.33	3.33
  1.23	1.23	1.23
  1.23	3.33	3.33
  1.23	wrealXState	wrealXState
  wrealXState	3.33	wrealXState
  wrealXState	wrealZState	wrealXState

Related Topics

• Selecting a wreal Resolution Function
• "Real Nets with More than One Driver"