Memory Copy

Copy data from and to memory section

• 

Description

Generated code for the Memory Copy block copies data from and to processor memory as configured by block parameters. When you use this block to copy an individual data element from a source to a destination, the block copies the element from the source, using the source data type, and then casts the data element to the specified destination data type.

Include as many instances of the Memory Copy block in a model as required to manipulate memory on a target processor. Each instance of the block works with one variable, address, or set of addresses provided to the block as input.

Specify the source and destination for a memory copy by using block parameters. You can use block parameters to control other aspects of a memory copy, such as:

• Initialization for memory locations

• Memory stride and offset during run time

• Write operations to memory during program initialization, during program termination, and at every sample time

• Insertion of custom ANSI^® C source code before and after each memory copy read and write operation (for example, to lock and unlock registers before and after accessing them)

The Memory Copy block performs operations at three periods during program execution:

• Initialization

• Real-time operations

• Termination

You can use block parameters to control when and how the block initializes memory, copies data or variables to and from memory, and terminates copy operations. The parameters enable you to turn on and off memory copy operations in the three periods independently.

Use the Memory Copy block and the Memory Allocate block to manipulate and allocate memory for custom device drivers, such as PCI bus drivers or codec-style drivers.

During simulation, the Memory Copy block does not perform an operation. The block output is not defined.

Ports

Input

src — Input data for copy operation

scalar | vector

The source data for the memory copy operation, specified as a scalar or vector.

Port Dependencies

To use this port as the source for the memory copy operation, set parameter Copy from to Input port.

Data Types: single | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64

&src — Address of input data for copy operation

scalar | vector

The memory address of source data for the copy operation, specified as a scalar or vector.

Port Dependencies

To use this port as the source for the memory copy operation, set parameter Copy from to Specified address and Specify address source to Input port. The Copy Memory block converts input port src to &src.

Data Types: single | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64

src ofs — Offset for data read during copy operation

scalar | vector

Offset to use for data read during the copy operation, specified as a scalar or vector.

Port Dependencies

To create this port, select parameter Use offset when reading and set Specify offset source to Input port.

Data Types: single | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64

&dst — Address of output data for copy operation

scalar | vector

The memory address to use as the data destination for the copy operation, specified as a scalar or vector.

Port Dependencies

To use this port as the destination for the memory copy operation, set parameter Copy to to Specified address and Specify address source to Input port. The Copy Memory block converts output port dst to input port &dst.

Data Types: single | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64

dst ofs — Offset for data written during copy operation

scalar | vector

Offset to use for data write during the copy operation, specified as a scalar or vector.

Port Dependencies

To create this port, select parameter Use offset when writing and set Specify offset source to Input port.

Data Types: single | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64

Output

dst — Output data for copy operation

scalar | vector

The data copied, specified as a scalar or vector.

Port Dependencies

To use this port as the destination for the memory copy operation, set parameter Copy to to Output port.

Data Types: single | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64

Parameters

Source

Specify the source sequential memory location for the copy operation. Specify the data type, size, and other attributes of the source variable.

Copy from — Input source for copy operation

Input port (default) | Specified address | Specified source code symbol

Specify the input source for the data read part of the copy operation. Choose from the sources listed in this table.

Source of Data Read	Parameter Value to Specify
src input port	Input port
Memory address	Specified address
Symbol (variable) in source code lookup table	Specified source code symbol

Parameter Dependencies

• If you select Specified address, use Specify address source to specify the source of the memory address and Address to specify the address.

• If you select Specified source code symbol, use Source code symbol to specify the symbol (variable) in the source code symbol table to copy.

• If you select Specified address or Specified source code symbol, change Data type to a value other than Inherit from source (the default). If you do not make this change, you receive an error message indicating that the data type cannot be inherited because the input port does not exist.

Specify address source — Source of memory address for input data

Specify via dialog (default) | Input port

Specify the source of the memory address of the input source for the copy operation. To specify a memory address for the source variable, select Specify via dialog. That selection enables an Address parameter that you use to specify the memory address.

To specify that the block get the address from the input port, select Input port. When you select Input port, the block input port label changes to &src.

Parameter Dependencies

• To enable this parameter, set Copy from to Specified address.

• If you select Specify via dialog, this parameter enables the Address parameter, which you use to specify the address of the source variable.

• If you select Specify via dialog, set Data type to a value other than Inherit from source (the default). If you do not make this change, you receive an error message indicating that the data type cannot be inherited because the input port does not exist.

• If you select Inport port , specify a data type for the Data type parameter.

Address — Memory address of source data

hex2dec('00001000') (default) | memory address in decimal or hexadecimal form with a conversion to decimal

Specify the memory address of the source data in decimal form or in hexadecimal form with a conversion to decimal as shown by the default value hex2dec('00001000').

This example converts Ox1000 to decimal form.

4096 = hex2dec('1000');

For this example, you can specify the address as 4096 or hex2dec('1000').

Parameter Dependencies

To enable this parameter, set Copy from to Specified address and Specify address source to Specify via dialog.

Source code symbol — Symbol in source code symbol table

myVariableSrc (default) | string | character vector

Specify the symbol (variable) in the source code symbol table to copy. The symbol that you specify must exist in the symbol table for your program. The block does not verify whether the symbol exists in the symbol table and whether you specify the symbol with valid syntax. Enter text that specifies the symbol exactly as it appears in your code.

Parameter Dependencies

• To enable this parameter, set Copy from to Specified source code symbol.

• Set Data type to a value other than Inherit from source (the default). If you do not make this change, you receive an error message indicating that the data type cannot be inherited because the input port does not exist.

Data type — Data type of data being copied

uint8 (default) | double | single | int8 | int16 | uint16 | int32 | uint32 | int64 | uint64 | boolean | Inherit from input port

Specify the data type of the source data being copied. To inherit the data type from the src input port, select Inherit from input port.

Data length — Number of data elements to copy

1 (default) | positive integer

Specify the number of elements to copy from the source location. Each element has the data type specified by the Data type parameter.

Use offset when reading — Use offset when reading input

off (default) | on

Specify whether the block uses an offset when reading input. The offset value is in elements of the specified data type. Specify the source of the offset by using the Specify offset source parameter.

Parameter Dependencies

• If you select this parameter, use Specify offset source to specify the source of the offset.

• Use Offset to specify the offset value.

Specify offset source — Source of input offset

Specify via dialog (default) | Input port

Specify the source of the input offset for the copy operation. To specify an offset value, select Specify via dialog. That selection enables an Offset parameter that you use to specify the offset value.

To specify for the block to get the offset from an input port, select Input port. When you select Input port, the block creates an input port labeled src ofs and reads the offset value from that port. The src ofs port enables your program to change the offset dynamically during program execution.

Parameter Dependencies

To enable this parameter, select Use offset when reading.

Offset — Number of values to skip before copying first value to destination

0 (default) | positive integer

Before copying the first value to the destination, specify the number of values to skip.

Parameter Dependencies

To enable this parameter, select Use offset when reading and set Specify offset source to Specify via dialog.

Stride — Spacing for reading input

1 (default) | positive integer

Specify the spacing for reading the input. By default, the stride value is one, meaning that the generated code reads the input data sequentially. When you add a stride value that is not equal to one, when reading input data, the generated code skips spaces in the source address equal to the stride.

These figures show the stride concept. In the first figure, data is copied without a stride. The second figure shows the results of a stride value of two. You can specify a stride value for the block output with parameter Stride on the Destination tab. You can also compare stride with the offset to see the differences.

Destination

Specify the destination memory location for the copy operation. Specify the attributes of the destination.

Copy to — Type of output destination for copy operation

Output port (default) | Specified address | Specified destination code symbol

Specify the type of output destination for the copy operation. Select one of the values listed in this table.

Parameter Value	Destination of Data Write
Output port	Block dst output port
Specified address	Memory location specified by parameters Specify address destination and Address
Specified source code symbol	Symbol (variable) specified by parameter Source code symbol

Parameter Dependencies

• If you select Specified address, use Specify address destination to specify the destination memory location.

• If you select Specified source code symbol, use Destination code symbol to specify the symbol (variable) in the source code symbol table to which to copy the variable.

Specify address source — Source of memory address for output destination

Specify via dialog (default) | Input port |

Specify the source of the destination memory address of the variable for the copy operation. To specify a memory address for the variable, select Specify via dialog. That selection enables an Address parameter that you use to specify the memory address. To specify that the block get the address from an input port, select Input port. When you select Input port, the block creates an input port labeled &dst. Changing the address dynamically means that you can use the block to copy different variables by providing the variable address from an upstream block in the model.

Parameter Dependencies

• To enable this parameter, set Copy to to Specified address.

• If you select Specify via dialog, this parameter enables the Address parameter, which you use to specify the address of the destination variable.

Address — Memory address of destination variable

hex2dec('00002000') (default) | memory address in decimal or hexadecimal form with a conversion to decimal

Specify the memory address of the destination variable in decimal form or in hexadecimal form with a conversion to decimal as shown by the default value hex2dec('00001000').

This example converts Ox2000 to decimal form.

8192 = hex2dec('2000');

For this example, you can specify the address as 8192 or hex2dec('2000').

Parameter Dependencies

To enable this parameter, set Copy to to Specified addressand Specify address source to Specify via dialog.

Source code symbol — Symbol in source code symbol table

myVariableDst (default) | string | character vector

Specify the symbol (variable) in the source code symbol table to which to copy the variable. The symbol that you specify, must exist in the symbol table for your program. The block does not verify whether the symbol exists in the symbol table and whether you specify the symbol with valid syntax. Enter text that specifies the symbol exactly as it appears in your code.

Parameter Dependencies

To enable this parameter, set Copy to to Specified source code symbol.

Data type — Data type of variable

uint32 (default) | double | single | int8 | uint8 | int16 | uint16 | uint32 | int64 | uint64 | boolean | Inherit from source

Specify the data type of the source variable. To inherit the data type from the source variable, select Inherit from source.

Use offset when writing — Use offset when writing output

off (default) | on

Specify whether the block uses an offset when writing output. The offset value is in elements of the specified data type. Specify the source of the offset by using the Specify offset source parameter.

Parameter Dependencies

If you select this parameter, use Specify offset source to specify the source of the offset. Use Offset to specify the offset value.

Specify offset source — Source of offset for output destination

Specify constant value (default) | Specify source code symbol

Specify the source of the offset for the output destination for the copy operation. To specify an offset value for the destination variable, select Specify via dialog. That selection enables an Offset parameter that you use to specify the offset value.

To specify that the block get the offset from the input port, select Input port. When you select Input port, the block adds an input port labeled dst ofs and reads the offset value from that port. The dst ofs port enables your program to change the offset dynamically during execution.

Parameter Dependencies

To enable this parameter, select Specify offset source.

Offset — Number of values to skip before writing first value to destination

0 (default) | positive integer

Before writing the first value to the destination, specify the number of values to skip.

Parameter Dependencies

To enable this parameter, select Use offset when writing and set Specify offset source to Specify via dialog.

Stride — Spacing for writing output

1 (default) | positive integer

Specify the spacing for writing the output. By default, the stride value is one meaning that the generated code writes the input data sequentially to the destination in consecutive locations. When you add a stride value that is not equal to one, when writing input data, the generated code skips spaces in the destination address equal to the stride.

This figure shows a stride value of three applied to writing the input to an output location. You can specify a stride value for the input with parameter Stride on the Source pane. As shown in the figure, you can use an input stride and an output stride at the same time to enable manipulating memory more fully.

Sample time — Rate of memory copy

inf (default) | scalar

Specify the rate at which the memory copy operation occurs in seconds. To use a constant sample time, specify Inf. To inherit the sample time from the input port or, when the block does not have an input port, from the Simulink^® model, specify -1.

Options

Configure parameters that control the copy process.

Set memory value at initialization — Set memory address during initialization

off (default) | on

Specify whether to initialize the memory address to a specific value during program initialization.

Parameter Dependencies

If you select this parameter, use a combination of parameters to configure the initialization value.

What to Configure	Parameter
Source of the initialization value	Specify initialization value source
Initialization value as a constant	Initialization value (constant)
Initialization value as a variable	Initialization value (source code symbol)
Initialization value as a mask to manipulate register contents at the bit level	Apply initialization value as mask
Apply a mask value	Bitwise operator

Specify initialization value source — Source of initialization value

Specify constant value (default) | Specify source code symbol

Specify the source of the initial value. To configure the source for initializing memory as a specific value, select Specify constant value. To configure the source as a variable (a symbol), select Specify source code symbol.

Parameter Dependencies

• To enable this parameter, select Set memory value at initialization.

• Use Initialization value (constant) or Initialization value (source code symbol) to specify the initial value.

Initialization value (constant) — Constant initialization value

1 (default) | scalar

Specify a constant value.

Parameter Dependencies

To enable this parameter, select Set memory value at initialization and set Set initialization value source to Specify constant value.

Initialization value (source code symbol) — Symbol in source code symbol table

myInitValueVariable (default) | string | character vector

Specify the symbol (variable) in the source code symbol table to use for the initialization value. The symbol that you specify must exist in the symbol table for your program. The block does not verify whether the symbol exists in the symbol table and whether you specify the symbol with valid syntax. Enter text that specifies the symbol exactly as it appears in your code.

Parameter Dependencies

To enable this parameter, select Set memory value at initialization and set Set initialization value source to Specify source code symbol.

Apply initialization value as mask — Apply initialization value as mask

off (default) | on

Specify whether to use the initialization value as a mask to manipulate register content at the bit level. Your initialization value is treated as a string of bits for the mask.

To define how to apply the mask value, specify a value for the Bitwise operator parameter.

To use your initialization value as a mask, the output from the copy must be a specific address. The output:

• Can be a symbol

• Cannot be an output port

Parameter Dependencies

If you select this parameter, use Bitwise operator to define how to apply the mask value.

Bitwise operator — Type of bitwise operation

bitwise AND (default) | bitwise OR | bitwise exclusive OR | left shift | right shift

Specify the type of bitwise operation to use as a mask to manipulate the memory value. Applying a mask to the copy process means that you can select individual bits in the result. For example, by applying a mask, you can read the value of the fifth bit.

Select one of the bitwise operations in this table.

Bitwise Operation	Description
bitwise AND	Apply the mask value as a bitwise AND to the value in the register.
bitwise OR	Apply the mask value as a bitwise OR to the value in the register.
bitwise exclusive OR	Apply the mask value as a bitwise exclusive OR to the value in the register.
left shift	Shift the bits in the register left by the number of bits represented by the initialization value. For example, if your initialization value is 3, the block shifts the register value to the left 3 bits. In this case, the value must be a positive integer.
right shift	Shift the bits in the register to the right by the number of bits represented by the initialization value. For example, if your initialization value is 6, the block shifts the register value to the right 6 bits. In this case, the value must be a positive integer.

Parameter Dependencies

To enable this parameter, select Apply initialization value as mask.

Set memory value at termination — Copy memory during program termination

off (default) | on

Specify that your program copy memory during program termination. Copying a value in memory during termination occurs in addition to a copy during program initialization.

Parameter Dependencies

If you select this parameter, you can use Set memory value only at initialization/termination to limit copy operations to occur during program initialization and termination only.

Termination value — Termination value

1 (default) | scalar | vector | matrix

Specify a value to write to memory during program termination.

Parameter Dependencies

To enable this parameter, select Set memory value at termination.

Set memory value only at initialization/termination — Copy memory value during program initialization and termination only

off (default) | on

Specify whether to perform copies during program initialization and termination only. When this parameter is cleared, the block performs copies during initialization, real-time operations, and termination. If you select this parameter, the block performs copies during initialization and termination only.

Insert custom code before memory write — Insert custom code before memory write

off (default) | on

Specify whether the code generator inserts custom ANSI C code immediately before the program writes to the specified memory location. You can use this parameter and Insert custom code after memory write to lock and unlock registers before and after accessing them. For example, some processors have registers that you might need to unlock and lock with EALLOW and EDIS macros before and after your program accesses them.

Parameter Dependencies

If you select this parameter, use Custom code to specify the custom ANSI C code to insert into the generated code immediately before the memory write operation.

Insert custom code after memory write — Custom code after memory write flag

off (default) | on

Specify whether the code generator inserts custom ANSI C code immediately after the program writes to the specified memory location. You can the Insert custom code before memory write and this parameter to lock and unlock registers before and after accessing them. For example, some processors have registers that you might need to unlock and lock with EALLOW and EDIS macros before and after your program accesses them.

Parameter Dependencies

If you select this parameter, use Custom code to specify the custom ANSI C code to insert into the generated code immediately after the memory write operation.

Custom code —

/* Custom Code Before Write*/ or /* Custom Code After Write*/ (default) | string | character vector

Specify custom ANSI C code to insert into the generated code immediately before or immediately after the memory write operation. Code that you specify appears in the generated code exactly as you enter it.

Parameter Dependencies

To enable this parameter, select Insert custom code before memory write or Insert custom code after memory write.

Version History

Introduced in R2011a