Perform in-place updates for Assignment and Bus Assignment blocks

Reuse the input and output variables of Bus Assignment and Assignment blocks

Model Configuration Pane: Code Generation / Optimization

Description

The Perform in-place updates for Assignment and Bus Assignment blocks parameter instructs the code generator to reuse the input and output variables of Bus Assignment and Assignment blocks if possible.

Dependencies

The parameter Signal Storage Reuse enables this parameter.

Settings

on (default) | off

On: Embedded Coder^® reuses the input and output variables of Bus Assignment and Assignment blocks if possible. Reusing these variables reduces data copies, conserves RAM consumption and increases code execution speed.
Off: Embedded Coder does not reuse the input and output variables of Bus Assignment and Assignment blocks.

Examples

expand all

Reduce Data Copies for Bus Assignment Blocks in Generated Code

For models containing a Bus Assignment block, if possible, the code generator uses the same variable for the block input and output. Reusing these variables reduces data copies, conserves RAM consumption and increases code execution speed.

For example, in bus_assignoptim, a bus signal containing six elements feeds into a Bus Assignment block and a Bus Selector block. The Bus Assignment block assigns new values to the bus element a1_real_array. This bus signal feeds into Out1.

Model containing a Bus Assignment block.

Generate code without the optimization by setting the Perform in-place updates for Assignment and Bus Assignment blocks parameter to off. Without the optimization the bus_assignoptim_step function contains this code:

void bus_assignoptim_step(void)
{
  real_T rtb_Assignment[36];
  int32_T i;

  /* Assignment: '<Root>/Assignment' incorporates:
   *  Inport: '<Root>/In1'
   *  Inport: '<Root>/In2'
   *  Product: '<Root>/Product'
   *  Selector: '<Root>/Selector'
   *  Sum: '<Root>/Sum1'
   */
  for (i = 0; i < 36; i++) {
    rtb_Assignment[i] = bus_assignoptim_U.In1.a1_real_array[i];
  }

  for (i = 0; i < 2; i++) {
    rtb_Assignment[(int32_T)(i + 22)] = (bus_assignoptim_U.In1.a1_real_array
      [(int32_T)(i + 22)] + bus_assignoptim_U.In1.a1_num) *
      bus_assignoptim_U.In2;
  }

  /* End of Assignment: '<Root>/Assignment' */

  /* Outport: '<Root>/Out' incorporates:
   *  BusAssignment: '<Root>/Bus Assignment'
   *  Inport: '<Root>/In1'
   */
  bus_assignoptim_Y.Out = bus_assignoptim_U.In1;

  /* BusAssignment: '<Root>/Bus Assignment' incorporates:
   *  Outport: '<Root>/Out'
   */
  for (i = 0; i < 36; i++) {
    bus_assignoptim_Y.Out.a1_real_array[i] = rtb_Assignment[i];
  }
}

The generated code contains the temporary array rtb_Assignment for holding data before this data is assigned to bus_assignoptim_Y.Out.a1_real_array.

Generate code with the optimization by setting the Perform in-place updates for Assignment and Bus Assignment blocks parameter to on. With the optimization, the bus_assignoptim_step function contains this code:

/* Model step function */
void bus_assignoptim_step(void)
{
  int32_T i;

  /* Outport: '<Root>/Out' incorporates:
   *  Inport: '<Root>/In1'
   *  SignalConversion: '<Root>/TmpBusAssignmentBufferAtBus AssignmentInport1'
   */
  bus_assignoptim_Y.Out = bus_assignoptim_U.In1;

  /* Assignment: '<Root>/Assignment' incorporates:
   *  Inport: '<Root>/In1'
   *  Inport: '<Root>/In2'
   *  Outport: '<Root>/Out'
   *  Product: '<Root>/Product'
   *  Selector: '<Root>/Selector'
   *  Sum: '<Root>/Sum1'
   */
  for (i = 0; i < 36; i++) {
    bus_assignoptim_Y.Out.a1_real_array[i] =
      bus_assignoptim_U.In1.a1_real_array[i];
  }

  for (i = 0; i < 2; i++) {
    bus_assignoptim_Y.Out.a1_real_array[(int32_T)(i + 22)] =
      (bus_assignoptim_U.In1.a1_real_array[(int32_T)(i + 22)] +
       bus_assignoptim_U.In1.a1_num) * bus_assignoptim_U.In2;
  }

  /* End of Assignment: '<Root>/Assignment' */
}

The generated code does not contain the temporary array rtb_Assignment1 for holding data. The generated code directly assigns this data to bus_assignoptim_Y.Out.a1_real_array.

Recommended Settings

Application	Setting
Debugging	No impact
Traceability	No impact
Efficiency	On
Safety precaution	No recommendation

Programmatic Use

Parameter: BusAssignmentInplaceUpdate

Type: character vector

Value: 'on' | 'off'

Default: 'on'

Version History

Introduced in R2017a