Memory Copy
Copy to and from memory section
Libraries:
Embedded Coder Support Package for STMicroelectronics STM32 Processors /
Utilities
Simulink Coder Support Package for STMicroelectronics Nucleo Boards /
Utilities
Simulink Support Package for Arduino Hardware /
Utilities
Description
In generated code, the Memory Copy block copies variables or data to and from processor memory as you have configured with block parameters. Your model can contain as many of these blocks as you require to manipulate memory on your processor.
Each block works with one variable, address, or set of addresses provided to the block. Using the parameters of this block you specify the source and the destination for the memory copy and options for initializing the memory locations.
At run time, you can change options like the memory stride and offset. You can write to memory at program initialization, at program termination, and at every sample time by selecting various parameters in the block. The initialization process occurs once, rather than occurring for every read and write operation.
With the custom source code options, the block enables you to add custom ANSI® C source code before and after each memory read and write (copy) operation.
Block Operations
This block performs operations at three periods during program execution: initialization, real-time operations, and termination. With the options for setting the memory initialization and termination, you control when and how the block initializes memory, copies to and from memory, and terminates memory operations. The parameters enable you to turn on and off memory operations in the three periods, independently of each other.
Copy Memory
When you use this block to copy an individual data element from the source to the destination, the block copies the element from the source in the source data type, and then casts the data element to the destination data type that you specify in the block parameters.
Ports
Input
Output
Parameters
The Memory Copy dialog box contains multiple tabs:
Source — Identifies the sequential memory location to copy from. Specify the data type, size, and other attributes of the source variable.
Destination — Specify the memory location to copy the source to and specify the attributes of the destination.
Options — Select various parameters to control the copy process.
Source
Copy from — Source from where the block reads data
Input port (default) | Specified address | Specified source code symbol
Input port— An input port becomes available. The port label on the block changes tosrc, indicating that the block expects data to come from the input port.Specified address— The block reads the source address from the option that you select from the Specify address source parameter.If you set the Specify address source parameter to
Specify via dialog, the block reads the source address that you specify in the Address parameter.If you set the Specify address source parameter to
Input Port, an input port becomes available. The port label on the block changes to&src, indicating that the block expects the address to come from the input portSpecified source code symbol— The block reads data from the symbol (variable) that you specify in the Source code symbol parameter.
If you select Specified address or Specified
source code symbol for the Copy from parameter,
change Data type from the default Inherit
from input port to one of the data types on the Data
type list.
Specify address source — Source of memory location to read data
Specify via dialog (default) | Input port
Specify via dialog— The block reads data from the memory location that you specify in the Address parameter.Input port— An input port becomes available. The port label on the block changes to&src, indicating that the block expects the source address to come from the input port. The ability to change the address dynamically means that you can the block to copy different variables by providing the variable address from an upstream block in your model.
Dependencies
This parameter appears only when you set the Copy
from parameter to Specified address.
Source code symbol — Symbol (variable) that contains the source address
myVariableSrc (default) | Any defined symbol
The block does not verify whether the symbol is valid. A symbol is valid only if it has an entry in the symbol table. If it is not valid you get an error when you try to compile, link, and run your generated code.
If the symbol contains a scalar value, specify & before
the symbol in this parameter. If the symbol contains a vector value,
specify only the symbol in this parameter.
Dependencies
This parameter appears only when you set the Copy
from parameter to Specified source code symbol.
Address — Memory location of input data
hex2dec('00001000') (default)
Specify the address in a decimal format or as a hexadecimal string
with single quotation marks. When you specify the address as a
hexadecimal string, pass that string as a parameter to the hex2dec function. This
function converts the string from the hexadecimal format to the decimal
format. The following example converts 0x1000 to its
decimal form.
4096 = hex2dec('1000');For this example, you can specify either 4096 or hex2dec('1000') as
the address.
Dependencies
This parameter appears only when you set the Copy
from parameter to Specified address and
set the Specify address source to Specify
via dialog.
Data type — Type of input data
Inherit from input port (default) | double | single | int8 | uint8 | int16 | uint16 | int32 | uint32 | boolean
Use this parameter to specify the data type of your input data.
When you set this parameter to Inherit from input port,
the block inherits the data type from the value at the block input
port.
Note
If you select the Copy from parameter to Specified
address or Specified source code symbol,
change the Data type parameter from
the default Inherit from input port to one of the
data types on the Data type list.
Data length — Number of elements to copy
1 (default) | Any integer value greater than 1
Use offset when reading — Specify an offset when reading data
off (default) | on
When you select this parameter, the block reads the source offset from the option that you select from the Specify offset source parameter. When you clear this parameter, the block reads data from the start address that you specify in the Copy from parameter.
Specify offset source — Source of offset for input data
Specify via dialog (default) | Input port
Specify via dialog— The block reads the offset value that you specify in the Offset parameter.Input port— An input port becomes available. The port label on the block changes tosrc ofs, indicating that the block expects the offset value to come from the input port. This port enables your program to change the offset dynamically during execution by providing the offset value as an input to the block.
Dependencies
This parameter appears only when you select the Use offset when reading parameter.
Offset — Number of memory locations added to the start address before starting to read data
0 (default) | Any integer value greater than 0
An Offset instructs the block whether to copy the first element of data at the input address, or skip values before starting to copy the input to the destination. The Offset defines how many input elements to skip before copying the first value to the destination.
Dependencies
This parameter appears only when you select the Use offset when reading parameter.
Stride — Spacing between the elements when reading input data
1 (default) | Any integer value greater than 1
Specify spacing between the elements when reading the input
data. A stride value equal to 1 means that the
generated code reads the input data sequentially. When you add a stride
value that is more than 1, the block skips that number of elements
and reads the elements from the resulting address.
The next two figures illustrate the stride concept. In the first figure, you see data copied without a stride.
The second figure shows a stride value equal to 2. A stride value 2 is applied when the block is copying the input to an output location. You can specify a stride value for the output from the Destination tab by using the Stride parameter.
Destination
Copy to — Source to where the block writes data
Input port (default) | Specified address | Specified source code symbol
Output port— An output port becomes available. The port label on the block changes todst, indicating that the block writes data to the output port.Specified address— The block copies data to the memory location that you that you specify in the Specify address source parameter.If you set the Specify address source parameter to
Specify via dialog, the block reads the destination address that you specify in the Address parameter.If you set the Specify address source parameter to
Input Port, an input port becomes available. The port label on the block changes to&dst, indicating that the block expects the destination address to come from the input portSpecified source code symbol— The block copies data to the symbol (variable) that you specify in the Source code symbol parameter.
Specify address source — Source of memory location to write data
Specify via dialog (default) | Input port
Specify via dialog— The block writes data to the location that you specify in the Address parameter.Input port— An input port becomes available. The port label on the block changes to&dst, indicating that the block expects the destination address to come from the input port. The ability to change the address dynamically means that you can the block to copy different variables by providing the variable address from an upstream block in your model.
Dependencies
This parameter appears only when you set the Copy
to parameter to Specified address.
Source code symbol — Symbol (variable) that contains the destination address
myVariableDst (default) | Any defined symbol
The block does not verify whether the symbol is valid. A symbol is valid only if it has an entry in the symbol table. If it is not valid you get an error when you try to compile, link, and run your generated code.
If the symbol contains a scalar value, specify & before
the symbol in this parameter. If the symbol contains a vector value,
specify only the symbol in this parameter.
Dependencies
This parameter appears only when you set the Copy
to parameter to Specified source code symbol.
Address — Memory location where the block writes data
hex2dec('00001000') (default)
Specify the address in a decimal format or as a hexadecimal string with single quotation
marks. When you specify the address as a hexadecimal string, pass that
vector as a parameter to the hex2dec function. This
function converts the string from hexadecimal format to decimal format.
The following example converts Ox2000 to decimal
form.
8192 = hex2dec('2000');For this example, you can specify either 8192 or hex2dec('2000') as
the address.
Dependencies
This parameter appears only when you set the Copy
to parameter to Specified address and
set the Specify address source to Specify
via dialog.
Data type — Type of output data
uint32 (default) | double | single | int8 | uint8 | int16 | uint16 | int32 | boolean | Inherit from source
Use this parameter to specify the data type of your output.
When you set this parameter to Inherit from source,
the block inherits the data type from the input signal at the block
input port.
Use offset when writing — Specify an offset when writing data
off (default) | on
When you select this parameter, the block reads the offset from the option that you select from the Specify offset source parameter. When you clear this parameter, the block reads data from the start address from the option that you specify in the Copy to parameter.
Specify offset source — Source of offset for writing data
Specify via dialog (default) | Input port
Specify via dialog— The block reads the offset value that you specify in the Offset parameter.Input port— An input port becomes available. The port label on the block changes todst ofs, indicating that the block expects the offset value to come from the input port. This port enables your program to change the offset dynamically during execution by providing the offset value as an input to the block.
Dependencies
This parameter appears only when you select the Use offset when writing parameter.
Offset — Number of memory locations added to the start address before starting to write data
0 (default) | Any integer value greater than 0
An Offset instructs the block whether to write the first element of data to the start address of destination, or skip one or more locations at the destination before writing the output. The Offset defines how many values to skip in the destination before writing the first value to the destination.
Dependencies
This parameter appears only when you select the Use offset when writing parameter.
Stride — Spacing between the elements when writing data
1 (default) | Any integer value greater than 1
Specify the spacing between the elements when writing the output data. A stride value equal to one means that the generated code writes the input data sequentially to the destination in consecutive locations. When you add a stride value that is more than 1, the output data is stored not sequentially, but skips elements equal to the stride.
This figure shows a stride value of 3 applied to writing the input to an output location. You can specify a stride value for the input from the Source tab by using the Stride parameter. As shown in the figure, you can apply input and output stride at the same time to manipulate your memory more fully.
Sample time — The rate, in seconds, at which memory copy operation occurs
Inf (default) | -1 | Any value greater than 0
The default value Inf instructs the block
to use a constant sample time. When you specify the Sample
time as -1, the Memory Copy block
inherits the sample time from the input. When there are no block inputs,
the block inherits the sample time from the Simulink® model.
Options
Set memory value at initialization — Specify a value and its source for initializing the destination
memory location
off (default) | on
When you select this option, you direct the block to initialize the memory location to a specific value when you initialize your program at run time. After you select this option, use the Specify initialization value source parameter to set the value that you want. Alternately, you can direct the block to get the initial value from the block input.
If you select this parameter, set the destination Copy
to parameter to either Specified address or Specified
source code symbol. If you do not change the parameter
value, you receive an error message that memory cannot be set at initialization
when the destination is output port.
Specify initialization value source — Specify the source of the initial value
Specify constant value (default) | Specify source code symbol
Specify constant value— Set a single value to use when your program initializes memory.The block reads the initialization value from the value that you specify in the Initialization value (constant) parameter.
Specify source code symbol— Specifies a variable (a symbol) to use for the initial value.The block reads the initialization value from the symbol that you specify in the Initialization value (source code symbol) parameter. The block does not verify whether the symbol is valid. A symbol is valid only if it has an entry in the symbol table. If it is not valid, you get an error when you try to compile, link, and run your generated code.
Dependencies
This parameter appears only when you select the Set memory value at initialization parameter.
Initialization value (constant) — A constant value to initialize the memory location when you initialize your program at run time
1 (default) | Any value
Dependencies
This parameter appears only when you select the Set
memory value at initialization parameter and set the Specify
initialization value source to Specify constant
value.
Initialization value (source code symbol) — A defined symbol (variable) that contains initialization value
myInitValueVariable (default) | Any defined symbol
When you specify a symbol, the block does not verify whether the symbol is valid. A symbol is valid only if it has an entry in the symbol table. If it is not valid, you get an error when you try to compile, link, and run your generated code.
Dependencies
This parameter appears only when you select the Set
memory value at initialization parameter and set the Specify
initialization value source to Specify source
code symbol.
Apply initialization value as mask — Specify the initialization value as mask
off (default) | on
The initialization value is treated as a string of bits for the mask.
The block performs the bitwise operation on the initialization value to manipulate register contents at the bit level. The operator that you specify in the Bitwise operator parameter determines the bitwise operation.
Note
To use your initialization value as a mask, set the destination Copy
to parameter to either Specified address or Specified
source code symbol.
Dependencies
This parameter appears only when you select the Set memory value at initialization parameter.
Bitwise operator — Specify bitwise operator for manipulating memory value in the register
bitwise AND (default) | bitwise OR | bitwise exclusive OR | left shift | right shift
To use the initialization value as a mask, from the Bitwise operator list, select one of the entries listed in this table.
Bitwise Operator List Entry | Description |
|---|---|
| Apply the mask value as a bitwise AND to the value in the register. |
| Apply the mask value as a bitwise OR to the value in the register. |
| Apply the mask value as a bitwise exclusive OR to the value in the register. |
| Shift the bits in the register to the 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 by 3 bits. In this case, the value must be a positive integer. |
| 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 by 6 bits. In this case, the value must be a positive integer. |
Dependencies
This parameter appears only when you select the Apply initialization value as mask parameter.
Set memory value at termination — Specify a value of the target memory after the write operation
off (default) | on
This parameter initializes memory when the program starts to access the target memory location and directs the program to set memory to a specific value when the program terminates.
Termination value — A constant value of the target memory after the write operation
1 (default) | Any value
This parameter appears only when you select the Set memory value at termination parameter.
Set memory value only at initialization/termination — Specify the periods of program execution at which the block performs copy operation
off (default) | on
This Memory Copy block performs operations at three periods during program execution: initialization, real-time operations, and termination. When you select this parameter, the block performs only the memory initialization and termination operations. It does not copy data during real-time operations.
Insert custom code before memory write — Specify a custom ANSI C code that you want to insert into the generated code before the block writes to a specified memory location
off (default) | on
The block inserts a custom ANSI C code that you specify in the Custom code parameter before the write operation.
You can use the custom code capability to lock and unlock registers before and after accessing them. For example, some processors have registers that you want to unlock with the EALLOW macro before your program accesses them.
Custom code — A custom ANSI C code that you insert into the generated code before the block writes to a specified memory location
/* Custom Code Before Write*/ (default)
The code that you specify in this parameter is the code that appears in the generated code.
Dependencies
To enable this parameter, select the Insert custom code before memory write parameter.
Insert custom code after memory write — Specify a custom ANSI C code that you insert into the generated code after the block writes to the specified memory location
off (default) | on
The block inserts a custom ANSI C code that you specify in the Custom code parameter after the write operation.
You can use the custom code capability to lock and unlock registers before and after accessing them. For example, some processors have registers that you want to lock with the EDIS macro after your program accesses them.
Custom code — A custom ANSI C code that you insert into the generated code after the block writes to the specified memory location
/* Custom Code After Write*/ (default)
The code that you specify in this parameter is the code that appears in the generated code.
Dependencies
This parameter appears only when you select the Insert custom code after memory write parameter.
More About
Extended Capabilities
Version History
Introduced in R2016b
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