【研发日记】Matlab/Simulink自动生成代码(二)——五种选择结构实现方法
文章目录
前言
见《深入拆解Simulink自动生成代码（一）——数据流处理》
Simulink实现选择结构
用Simulink实现选择结构的一个最简单编程举例如下：
自动生成C代码
上述选择结构的Simulink自动生成的对应C代码如下：
/* Switch: '<S2>/Switch' incorporates:
* UnitDelay: '<S3>/Output'
*/
if (CodeGenerate_DW.Output_DSTATE > 0) {
/* Outport: '<Root>/y1' incorporates:
* Constant: '<S2>/Constant'
*/
CodeGenerate_Y.y1 = 5.0;
} else {
/* Outport: '<Root>/y1' incorporates:
* Constant: '<S2>/Constant2'
*/
CodeGenerate_Y.y1 = 10.0;
}
/* End of Switch: '<S2>/Switch' */
/* Switch: '<S5>/FixPt Switch' incorporates:
* Constant: '<S4>/FixPt Constant'
* Constant: '<S5>/Constant'
* Sum: '<S4>/FixPt Sum1'
* UnitDelay: '<S3>/Output'
*/
if ((uint8_T)(CodeGenerate_DW.Output_DSTATE + 1U) > 7) {
CodeGenerate_DW.Output_DSTATE = 0U;
} else {
CodeGenerate_DW.Output_DSTATE++;
}
/* End of Switch: '<S5>/FixPt Switch' */变式一
基于上述举例，增加选择结构的选项，生成的对应代码如下所示：
/* SwitchCase: '<S2>/Switch Case' incorporates:
* UnitDelay: '<S3>/Output'
*/
switch (CodeGenerate_DW.Output_DSTATE) {
case 1:
/* Outputs for IfAction SubSystem: '<S2>/Switch Case Action Subsystem' incorporates:
* ActionPort: '<S4>/Action Port'
*/
/* Outport: '<Root>/y1' incorporates:
* Constant: '<S2>/Constant1'
* Inport: '<S4>/In1'
*/
CodeGenerate_Y.y1 = 5.0;
/* End of Outputs for SubSystem: '<S2>/Switch Case Action Subsystem' */
break;
case 2:
/* Outputs for IfAction SubSystem: '<S2>/Switch Case Action Subsystem1' incorporates:
* ActionPort: '<S5>/Action Port'
*/
/* Outport: '<Root>/y1' incorporates:
* Constant: '<S2>/Constant3'
* Inport: '<S5>/In1'
*/
CodeGenerate_Y.y1 = 10.0;
/* End of Outputs for SubSystem: '<S2>/Switch Case Action Subsystem1' */
break;
case 3:
/* Outputs for IfAction SubSystem: '<S2>/Switch Case Action Subsystem2' incorporates:
* ActionPort: '<S6>/Action Port'
*/
/* Outport: '<Root>/y1' incorporates:
* Constant: '<S2>/Constant4'
* Inport: '<S6>/In1'
*/
CodeGenerate_Y.y1 = 15.0;
/* End of Outputs for SubSystem: '<S2>/Switch Case Action Subsystem2' */
break;
default:
/* Outputs for IfAction SubSystem: '<S2>/Switch Case Action Subsystem3' incorporates:
* ActionPort: '<S7>/Action Port'
*/
/* Outport: '<Root>/y1' incorporates:
* Constant: '<S2>/Constant5'
* Inport: '<S7>/In1'
*/
CodeGenerate_Y.y1 = 0.0;
/* End of Outputs for SubSystem: '<S2>/Switch Case Action Subsystem3' */
break;
}
/* End of SwitchCase: '<S2>/Switch Case' */
/* Switch: '<S9>/FixPt Switch' incorporates:
* Constant: '<S8>/FixPt Constant'
* Constant: '<S9>/Constant'
* Sum: '<S8>/FixPt Sum1'
* UnitDelay: '<S3>/Output'
*/
if ((uint8_T)(CodeGenerate_DW.Output_DSTATE + 1U) > 7) {
CodeGenerate_DW.Output_DSTATE = 0U;
} else {
CodeGenerate_DW.Output_DSTATE++;
}
/* End of Switch: '<S9>/FixPt Switch' */变式二
基于上述举例，升级选择结构的判断条件，生成的对应代码如下所示：
real_T tmp;
/* Math: '<S2>/Mod' incorporates:
* Constant: '<S2>/Constant6'
* DataTypeConversion: '<S2>/Data Type Conversion'
* Math: '<S2>/Mod1'
* Math: '<S2>/Mod2'
* UnitDelay: '<S6>/Output'
*/
tmp = rt_modd_snf((real_T)CodeGenerate_DW.Output_DSTATE, 3.0);
/* Outputs for Enabled SubSystem: '<S2>/Subsystem' incorporates:
* EnablePort: '<S7>/Enable'
*/
/* RelationalOperator: '<S3>/Compare' incorporates:
* Constant: '<S3>/Constant'
* Math: '<S2>/Mod'
*/
if (tmp == 0.0) {
/* Merge: '<S2>/Merge1' incorporates:
* Constant: '<S2>/Constant7'
* Inport: '<S7>/In1'
*/
CodeGenerate_B.Merge1 = 5.0;
}
/* End of RelationalOperator: '<S3>/Compare' */
/* End of Outputs for SubSystem: '<S2>/Subsystem' */
/* Outputs for Enabled SubSystem: '<S2>/Subsystem1' incorporates:
* EnablePort: '<S8>/Enable'
*/
/* RelationalOperator: '<S4>/Compare' incorporates:
* Constant: '<S4>/Constant'
*/
if (tmp == 1.0) {
/* Merge: '<S2>/Merge1' incorporates:
* Constant: '<S2>/Constant9'
* Inport: '<S8>/In1'
*/
CodeGenerate_B.Merge1 = 10.0;
}
/* End of RelationalOperator: '<S4>/Compare' */
/* End of Outputs for SubSystem: '<S2>/Subsystem1' */
/* Outputs for Enabled SubSystem: '<S2>/Subsystem2' incorporates:
* EnablePort: '<S9>/Enable'
*/
/* RelationalOperator: '<S5>/Compare' incorporates:
* Constant: '<S5>/Constant'
*/
if (tmp == 2.0) {
/* Merge: '<S2>/Merge1' incorporates:
* Constant: '<S2>/Constant11'
* Inport: '<S9>/In1'
*/
CodeGenerate_B.Merge1 = 15.0;
}
/* End of RelationalOperator: '<S5>/Compare' */
/* End of Outputs for SubSystem: '<S2>/Subsystem2' */
/* Switch: '<S11>/FixPt Switch' incorporates:
* Constant: '<S10>/FixPt Constant'
* Constant: '<S11>/Constant'
* Sum: '<S10>/FixPt Sum1'
* UnitDelay: '<S6>/Output'
*/
if ((uint8_T)(CodeGenerate_DW.Output_DSTATE + 1U) > 7) {
CodeGenerate_DW.Output_DSTATE = 0U;
} else {
CodeGenerate_DW.Output_DSTATE++;
}
/* End of Switch: '<S11>/FixPt Switch' */
/* Outport: '<Root>/y1' incorporates:
* MATLAB Function: '<Root>/MATLAB Function2'
*/
CodeGenerate_Y.y1 = CodeGenerate_B.Merge1;变式三
基于上述举例，用MATLAB Function来实现，生成的对应代码如下所示：
#include "untitled.h"
#include "untitled_private.h"
/* Block states (default storage) */
DW_untitled_T untitled_DW;
/* External outputs (root outports fed by signals with default storage) */
ExtY_untitled_T untitled_Y;
/* Real-time model */
static RT_MODEL_untitled_T untitled_M_;
RT_MODEL_untitled_T *const untitled_M = &untitled_M_;
/* Model step function */
void untitled_step(void)
{
uint8_T rtb_Output;
/* UnitDelay: '<S1>/Output' */
rtb_Output = untitled_DW.Output_DSTATE;
/* Switch: '<S4>/FixPt Switch' incorporates:
* Constant: '<S3>/FixPt Constant'
* Constant: '<S4>/Constant'
* Sum: '<S3>/FixPt Sum1'
* UnitDelay: '<S1>/Output'
*/
if ((uint8_T)(untitled_DW.Output_DSTATE + 1U) > 7) {
untitled_DW.Output_DSTATE = 0U;
} else {
untitled_DW.Output_DSTATE++;
}
/* End of Switch: '<S4>/FixPt Switch' */
/* MATLAB Function: '<Root>/MATLAB Function' */
switch (rtb_Output) {
case 1:
/* Outport: '<Root>/y' */
untitled_Y.y = 5.0;
break;
case 2:
/* Outport: '<Root>/y' */
untitled_Y.y = 10.0;
break;
case 3:
/* Outport: '<Root>/y' */
untitled_Y.y = 15.0;
break;
default:
/* Outport: '<Root>/y' */
untitled_Y.y = 0.0;
break;
}
/* End of MATLAB Function: '<Root>/MATLAB Function' */
}变式四
基于上述举例，用Stateflow配合Simulink Function来实现选择结构，参见《【研发日记】嵌入式处理器技能解锁(一)——多任务异步执行调度的三种方法》，示例如下：
总结
以上就是本人拆解Simulink模块自动生成代码时，讲解的第二部分。主要针对Simulink的选择结构，展示了这类模块的使用方法，并对比了相应的C代码。
后续还会更新Simulink其他的几种模块，欢迎评论区留言、点赞、收藏和关注，这些鼓励和支持都将成为笔者持续分享的动力。
另外，上述例程使用的Demo工程可以到笔者的主页查找和下载。
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