在编译时将多个文件中的变量收集到单个连续的内存块中

问题描述

我想定义（并初始化）一系列* .c文件中的一些结构体的实例，但我希望它们在编译时收集到一个连续的数组中。我一直在研究使用一个自定义的部分，并使用该部分的开始和结束地址作为结构数组的开始和结束，但我还没有完全弄清楚细节，我宁愿不写一个自定义链接器脚本，如果我可以摆脱它。下面是我的第一个黑客的总结，它不起作用：

  // mystruct.h：
 typedef struct {int a; int b; } mystruct; 
 
 // mycode1.c：
 #includemystruct.h
 mystruct instance1 = {1,2} __attribute __（（section（。mysection）））; 
 
 // mycode2.c：
 #includemystruct.h
 mystruct instance2 = {3，4} __attribute __（（section（。mysection）））; 
 
 // mystruct.c：
 extern char __mysection_start; 
 extern char __mysection_end; 
 void myfunc（void）{
 mystruct * p =& __ mysection_start; 
 for（; p<& __ mysection_end; p ++）{
 //使用p-> a和p-> b 
} 
} 
  

解决方案

为了使用自定义部分，您必须定义其起始地址在自定义链接脚本中。复制您设备的链接描述文件并将其添加到 SECTIONS 块中： c> / * in custom.gld * /
mysection 0x2000：
{
*（mysection）;
>> data

为了让您的对象进入本节，请使用section属性：

  / * mycode1.c：* / 
 #includemystruct.h
 mystruct __attribute__ （（section（mysection）））instance1 = {1，2}; 
 $ b $ * mycode2.c：* / 
 #includemystruct.h
 mystruct __attribute __（（section（mysection）））instance2 = {3,4} ; 
  

现在，要获得自定义区域的边界，可以使用 .startof。（section_name）和 .sizeof。（section_name）汇编运算符：

  #includemystruct.h
 
 char * mysection_start; 
 char * mysection_end; 
 size_t mysection_size; 
 
 int main（void）
 {
 asm（mov＃.startof。（mysection），W12）; 
 asm（mov＃.sizeof。（mysection），W13）; 
 asm（mov W12，_mysection_start）; 
 asm（mov W13，_mysection_size）; 
 
 mysection_end = mysection_start + mysection_size; 
 
 mystruct * p =（mystruct *）mysection_start; $; 
 for（;（char *）p  {
 //使用p-> a和p-> b 
} 
} 
  

I'd like to define (and initialize) a number of instances of a struct across a number of *.c files, but I want them to gather at compile time into a single contiguous array. I've been looking into using a custom section and using the section's start and end address as the start and end of the array of structs, but I haven't quite figured out the details yet, and I'd rather not write a custom linker script if I can get away with it. Here's a summary of my first hack which didn't quite work:

// mystruct.h:
typedef struct { int a; int b; } mystruct;

// mycode1.c:
#include "mystruct.h"
mystruct instance1 = { 1, 2 } __attribute__((section(".mysection")));

// mycode2.c:
#include "mystruct.h"
mystruct instance2 = { 3, 4 } __attribute__((section(".mysection")));

// mystruct.c:
extern char __mysection_start;
extern char __mysection_end;
void myfunc(void) {
    mystruct * p = &__mysection_start;
    for ( ; p < &__mysection_end ; p++) {
        // do stuff using p->a and p->b
    }
}

解决方案

In order to use a custom section, you must define its start address in a custom linker script. Copy your device's linker script and add the new section into its SECTIONS block:

/* in custom.gld */
mysection 0x2000 :
{
    *(mysection);
} >data

To make your objects go into this section, use the section attribute:

/* mycode1.c: */
#include "mystruct.h"
mystruct __attribute__((section("mysection"))) instance1 = { 1, 2 };

/* mycode2.c: */
#include "mystruct.h"
mystruct __attribute__((section("mysection"))) instance2 = { 3, 4 };

Now, to get the boundaries of your custom section, you can use the .startof.(section_name) and .sizeof.(section_name) assembler operators:

#include "mystruct.h"

char *mysection_start;
char *mysection_end;
size_t mysection_size;

int main(void)
{
    asm("mov #.startof.(mysection), W12");
    asm("mov #.sizeof.(mysection), W13");
    asm("mov W12, _mysection_start");
    asm("mov W13, _mysection_size");

    mysection_end = mysection_start + mysection_size;

    mystruct *p = (mystruct *)mysection_start;
    for ( ; (char *)p < mysection_end ; p++)
    {
        // do stuff using p->a and p->b
    }
}

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