Simulink Embeded Coder生成的C代码解析

本文以一个简单的模型为例讲述Embeded Coder生成的C代码的架构。

模型

      模型如下图，名为test.

 其中Subsystem1中为与门，其它2个子系统的输入端和输出端直接相连。之后用Embeded Coder生成C代码，选择64位Windows系统作为运行环境。

生成的文件

     生成2个头文件: rtwtypes.h, test.h. 

     2个源文件: ert_main.c, test.c

      rtwtypes.h定义一些类型，如int16_T. 不细说这个头文件。下面讲解其它文件。

test.h

     

typedef struct tag_RTM RT_MODEL;
 
/* External inputs (root inport signals with default storage) */
typedef struct {
  boolean_T In1;                       /* '<Root>/In1' */
  boolean_T In2;                       /* '<Root>/In2' */
} ExtU;
 
/* External outputs (root outports fed by signals with default storage) */
typedef struct {
  boolean_T Out1;                      /* '<Root>/Out1' */
  boolean_T Out2;                      /* '<Root>/Out2' */
} ExtY;
 
/* Real-time Model Data Structure */
struct tag_RTM {
  const char_T * volatile errorStatus;
};

将输入、输出的数据用结构体封装起来。

test.c

      

 
 
#include "test.h"
 
/* External inputs (root inport signals with default storage) */
ExtU rtU;
 
/* External outputs (root outports fed by signals with default storage) */
ExtY rtY;
 
/* Real-time model */
static RT_MODEL rtM_;
RT_MODEL *const rtM = &rtM_;
 
/* Model step function */
void test_step(void)
{
  boolean_T rtb_LogicalOperator;
 
  /* Logic: '<S1>/Logical Operator' incorporates:
   *  Inport: '<Root>/In1'
   *  Inport: '<Root>/In2'
   */
  rtb_LogicalOperator = (rtU.In2 && rtU.In1);
 
  /* Outport: '<Root>/Out1' */
  rtY.Out1 = rtb_LogicalOperator;
 
  /* Outport: '<Root>/Out2' */
  rtY.Out2 = rtb_LogicalOperator;
}
 
/* Model initialize function */
void test_initialize(void)
{
  /* (no initialization code required) */
  rtU.In1 = 1;
  rtU.In2 = 1;
}
 
 

rtM_ 是运行时数据，这个例子中只存储了字符串errorStatus. initialize函数中原来是空的，里面的初始化的代码可以自己加上去，当作初始化输入。 step函数是运行中的每一步。

ert_main.c

     这是主函数所在源文件。代码如下

 
 
#include <stddef.h>
#include <stdio.h>            /* This example main program uses printf/fflush */
#include "test.h"                      /* Model's header file */
 
 
void rt_OneStep(void);
void rt_OneStep(void)
{
  static boolean_T OverrunFlag = false;
 
  /* Disable interrupts here */
 
  /* Check for overrun */
  if (OverrunFlag) {
    rtmSetErrorStatus(rtM, "Overrun");
    return;
  }
 
  OverrunFlag = true;
 
  /* Save FPU context here (if necessary) */
  /* Re-enable timer or interrupt here */
  /* Set model inputs here */
 
  /* Step the model */
  test_step();
 
  /* Get model outputs here */
 
  /* Indicate task complete */
  OverrunFlag = false;
 
  /* Disable interrupts here */
  /* Restore FPU context here (if necessary) */
  /* Enable interrupts here */
}
 
/*
 * The example "main" function illustrates what is required by your
 * application code to initialize, execute, and terminate the generated code.
 * Attaching rt_OneStep to a real-time clock is target specific.  This example
 * illustrates how you do this relative to initializing the model.
 */
int_T main(int_T argc, const char *argv[])
{
  /* Unused arguments */
  (void)(argc);
  (void)(argv);
 
  /* Initialize model */
  test_initialize();
 
 
  fflush((NULL));
  int i = 0;
  while (rtmGetErrorStatus(rtM) == (NULL) && i <= 5) 
  {
    rt_OneStep();
     ++i;
     printf("%d %u\n", i, rtY.Out1);
  }
 
  /* Disable rt_OneStep here */
  return 0;
}
 

代码中原本有很多注释，while循环是空的。现在我在while循环中加了控制循环次数的变量i，以及调用rt_OneStep函数，这个函数是test_step()函数的封装。函数中使用静态变量OverrunFlag，确保在多线程中，不会同时运行多个test_step().