如何分配预处理器指令

Question

I have a macro as follow.

#define WR_BLK_SIZE_REGINFO 123

Am using this macro in a library project(.a). Library projects are pre-compiled where the size of "WR_BLK_SIZE_REGINFO" cannot be changed as it is statically allocated in the library project.

Now how can I dynamically allocate preprocessor directives code?

I want something like below. Is that possible?

#define WR_BLK_SIZE_REGINFO malloc

Let me brief out more if confused.

- What for this macro is used?

Ans: This macro is used in various files of my library project. For reducing code complexity I am using a macro to fix a size

• Why do you want to malloc the macro?

Ans: Am doing a library project, where this library projects will be used in many controllers. Where each controller has its own memory set. So I can't fix the size of that macro statically. As it needs to be varied based on controllers memory.

Demonstrate some code?

Sample.h

#define WR_BLK_SIZE_REGINFO 123

sample.c

if( !((numItems >= 1) && (numItems <= WR_BLK_SIZE_REGINFO)) )
{
    // logic            
}

sample1.c

if( !((numItemsWrite >= 1) && (numItemsWrite <= WR_BLK_SIZE_REGINFO)) )
{
    // logic    
}

Note1: all the above files are library files which are pre-compiled and "123" is fixed here, which I don't want it to be fixed. I want to allocate dynamically.

Note2: Am not sure whether malloc is the right choice. All I need is I wanted to input "123" at run time in the library project or during compile time of application project(Input 123 from application project to library project)

Note3: Library project are built using MPLAB X IDE, basically it is a microchip project.

Answer 1

In sample.h:

int get_wr_blk_size(void);
#define WR_BLK_SIZE_REGINFO get_wr_blk_size()

In some C file somewhere

static int wr_blk_size = 123;
static int set_wr_blk_size(int j) { wr_blk_size = j; }
int get_wr_blk_size(void) { return wr_blk_size; }

Note that any code that assumes WR_BLK_SIZE_REGINFO is a compile-time constant will have to be rewritten since it isn't anymore.