iswritable (MATLAB Link for Code Composer Studio Development Tools)

MATLAB Link for Code Composer Studio Development Tools

Determine if MATLAB can write to the specified memory block

Syntax

iswritable(cc,address,'datatype',count)
iswritable(cc,address,'datatype')

Description

iswritable(cc,address,'datatype',count) returns 1 if MATLAB can write to the memory block defined by the address, count, and datatype input arguments on the processor referred to by cc. When the processor cannot write to any portion of the specified memory block, iswritable returns 0. Notice that you use the same memory block specification for this function as you use for the write function. The data block being tested begins at the memory location defined by address. count determines the number of values to write. datatype defines the format of data stored in the memory block. iswritable uses the datatype parameter to determine the number of bytes to write per stored value. For details about each input parameter, read the following descriptions.

address -- iswritable uses address to define the beginning of the memory block to write to. You provide values for address as either decimal or hexadecimal representations of a memory location in the target processor. The full address at a memory location consists of two parts: the offset and the memory page, entered as a vector [location, page], a string, or a decimal value. In cases where the processor has only one memory page, as is true for many digital signal processors, the page portion of the memory address is 0. By default, ccsdsp sets the page to 0 at creation if you omit the page property as an input argument to set the page parameter.

For processors that have one memory page, setting the page value to 0 lets you specify all memory locations in the processor using the memory location without the page value.

Table 3-5: Examples of Address Property Values
Property Value
Address Type
Interpretation

'1F'
String
Location is 31 decimal on the page referred to by cc(page)

10
Decimal
Address is 10 decimal on the page referred to by cc(page)

[18,1]
Vector
Address location 10 decimal on memory page 1 (cc(page) = 1)

**Table 3-5: Examples of Address Property Values**
Property Value	Address Type	Interpretation
'1F'	String	Location is 31 decimal on the page referred to by `cc(page)`
10	Decimal	Address is 10 decimal on the page referred to by `cc(page)`
[18,1]	Vector	Address location 10 decimal on memory page 1 (`cc(page) = 1`)

To specify the address in hexadecimal format, enter the address property value as a string. iswritable interprets the string as the hexadecimal representation of the desired memory location. To convert the hex value to a decimal value, the function uses hex2dec. Note that when you use the string option to enter the address as a hex value, you cannot specify the memory page. For string input, the memory page defaults to the page specified by cc(page).

count--a numeric scalar or vector that defines the number of datatype values to test for being writable. To assure parallel structure with write, count can be a vector to define multidimensional data blocks. This function always tests a block of data whose size is the total number of elements in matrix specified by the input vector. If count is the vector [10 10 10]

```
iswritable(cc,31,[10 10 10])
```

iswritable writes 1000 values (10*10*10) to the target processor. For a 2-dimensional matrix defined with count as

```
iswritable(cc,31,[5 6])
```

iswritable writes 30 values to the processor.

datatype--a string that represents a MATLAB data type. The total memory block size is derived from the value of count and the specified datatype. datatype determines how many bytes to check for each memory value. iswritable supports the following data types:

datatype String
Description

'double'
Double-precision floating point values

'int8'
Signed 8-bit integers

'int16'
Signed 16-bit integers

'int32'
Signed 32-bit integers

'single'
Single-precision floating point data

'uint8'
Unsigned 8-bit integers

'uint16'
Unsigned 16-bit integers

'uint32'
Unsigned 32-bit integers

`datatype` String	Description
'`double`'	Double-precision floating point values
'`int8`'	Signed 8-bit integers
'`int16`'	Signed 16-bit integers
'`int32`'	Signed 32-bit integers
'`single`'	Single-precision floating point data
'`uint8`'	Unsigned 8-bit integers
'`uint16`'	Unsigned 16-bit integers
'`uint32`'	Unsigned 32-bit integers

iswritable(cc,address,'datatype') returns 1 if the processor referred to by cc can write to the memory block defined by the address, and count input arguments. When the processor cannot write any portion of the specified memory block, iswritable returns 0. Notice that you use the same memory block specification for this function as you use for the write function. The data block tested begins at the memory location defined by address. When you omit the count option, count defaults to one.

Note iswritable relies on the memory map option in CCS IDE. If you did not properly define the memory map for the processor in CCS IDE, this function does not produce useful results. Refer to your Code Composer Studio documentation for more information on configuring memory maps.

Like the isreadable, read, and write functions, iswritable checks for valid address values. Illegal address values would be any address space larger than the available space for the processor--2³² for the C6xxx processor family and 2¹⁶ for the C5xxx series. When the function identifies an illegal address, it returns an error message stating that the address values are out of range.

Examples

When you write scripts to run models in MATLAB and CCS IDE, the iswritable function is very useful. Use iswritable to check that the channel to which you are writing to is indeed configured properly.

cc = ccsdsp;
rx = cc.rtdx;

% Define read and write channels to the target linked by cc.
open(rx,'ichannel','r');
open(rx,'ochannel','w');
enable(rx,'ochannel');
enable(rx,'ichannel');

iswritable(rx,'ochannel')
ans=
    1
iswritable(rx,'ichannel')
ans=
    0

Now that your script knows that it can write to 'ichannel', it proceeds to write messages as required.

See Also
hex2dec, iswritable, read

isvisible list