Coder - Create constant for specifying array size

7 次查看（过去 30 天）
amin ya
amin ya 2019-3-15
编辑： amin ya 2019-3-16
How can I create a constant variable in MATLAB (and its results the generated C code), so I can use it later in my code to specify the size of variables.
In C, we usually do this:
const int arraySize = 5;
int array[arraySize];
When I write the following in the MATLAB, coder just repalces arraySize with the actual number which is 5:
arraySize=5;
array=zeros(1,arraySize); % zeros is just used for specifying size
(This array size may be repeated throughout the different functions and code many times, so global probably may be related to this)
I want to use static memory allocation as long as it is possible.
Related also to this question: https://www.mathworks.com/matlabcentral/answers/84419-declaring-const-variable-in-generated-code

请先登录，再回答此问题。

回答（1 个）

Fangjun Jiang
Fangjun Jiang 2019-3-15
Please refer to the document
Code Generation for Variable-Size Arrays
web(fullfile(docroot, 'simulink/ug/what-is-variable-size-data.html'))
Control Memory Allocation for Variable-Size Arrays in a MATLAB FunctionBlock
web(fullfile(docroot, 'ecoder/ug/control-memory-allocation-for-variable-size-arrays-in-a-matlab-function-block.html'))
  1 个评论
amin ya
amin ya 2019-3-16
编辑：amin ya 2019-3-16
This is not useful.
I want to have an array that its size is not hardcoded via number all over the code. This may be related to constant folding which I can not disable!
I want to specify the size at the beginning of the code like how we do in C code using one of the followings:
constant int arraySize=5
or
#define arraysize 5
--------------------------------------------------------------------------------
For example the generated code for my This example, where a is defined as a global constant int8(5),
function A=coder()
global a
A=zeros(a,a);
end
is this, which you see 5 is used in the code instead of being defined in the beginning
#include <string.h>
#include "coder.h"
void coder(double A[5][5])
{
memset(&A[0][0], 0, sizeof(double) << 16);
}
--------------------------------------------------------------------------------
I tried using the following but it does not allow me to use a in MATLAB calculations:
a=coder.opaque('const int16','5');
A=zeros(a,a);

请先登录，再进行评论。

类别

在 Help Center 和 File Exchange 中查找有关 Algorithm Design Basics 的更多信息

标签

产品


版本

R2018b

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by