cgen.cpp

内含源代码和编译实验报告

			if(p2)   generate_stmt(p2);
			strcpy(register1,"ax");
			if(p2)	strcpy(register2,"bx");
			if(strcmp(pa_exp->m_strIDname,"+")==0){
				READTWO									//宏，读取两个源操作数。
				AllGlobals.code.write("\nadd\t",5);
				AllGlobals.code.write(register1,2);
				AllGlobals.code.write(",",1);
				AllGlobals.code.write(register2,2);		//两个源操作数相加，结果入栈。
				AllGlobals.code.write("\npush\t",6);
				AllGlobals.code.write(register1,2);
			}
			else if(strcmp(pa_exp->m_strIDname,"-")==0
						|| strcmp(pa_exp->m_strIDname,"!=")==0){
				READTWO
				AllGlobals.code.write("\nsub\t",5);
				AllGlobals.code.write(register1,2);
				AllGlobals.code.write(",",1);
				AllGlobals.code.write(register2,2);
				AllGlobals.code.write("\npush\t",6);
				AllGlobals.code.write(register1,2);
			}
			else if(strcmp(pa_exp->m_strIDname,"*")==0){
				READTWO
				AllGlobals.code.write("\nmul\t",5);
				AllGlobals.code.write(register2,2);
				AllGlobals.code.write("\npush\t",6);
				AllGlobals.code.write(register1,2);
			}
			else if(strcmp(pa_exp->m_strIDname,"/")==0){
				READTWO
				AllGlobals.code.write("\ndiv\tbx\n",8);
				AllGlobals.code.write("cbw\t",4);	//除法所得的商要进行位扩展。
				AllGlobals.code.write("\npush\t",6);
				AllGlobals.code.write(register1,2);
			}
			else if(strcmp(pa_exp->m_strIDname,"=")==0){
				READTWO
				AllGlobals.code.write("\nmov\t",5);
				AllGlobals.code.write(pa_exp->m_pchild[0]->m_strIDname,
							strlen(pa_exp->m_pchild[0]->m_strIDname));
				AllGlobals.code.write(",",1);
				AllGlobals.code.write(register2,2);
			}
			else if(strcmp(pa_exp->m_strIDname,"<")==0 ||
							strcmp(pa_exp->m_strIDname,"<=")==0
								|| strcmp(pa_exp->m_strIDname,"==")==0){
				READTWO
				AllGlobals.code.write("\nsub\t",5);
				AllGlobals.code.write(register1,2);
				AllGlobals.code.write(",",1);
				AllGlobals.code.write(register2,2);
				AllGlobals.code.write("\npush\t",6);
				AllGlobals.code.write(register1,2);
			}
			else if(strcmp(pa_exp->m_strIDname,">")==0 ||
							strcmp(pa_exp->m_strIDname,">=")==0){
				READTWO
				AllGlobals.code.write("\nsub\t",5);
				AllGlobals.code.write(register2,2);
				AllGlobals.code.write(",",1);
				AllGlobals.code.write(register1,2);
				AllGlobals.code.write("\npush\t",6);
				AllGlobals.code.write(register1,2);
			}
			else if(strcmp(pa_exp->m_strIDname,"!")==0){
				AllGlobals.code.write("\npop\t",5);
				AllGlobals.code.write(register1,2);
				AllGlobals.code.write("\nnot\t",5);
				AllGlobals.code.write(register1,2);
				AllGlobals.code.write("\npush\t",6);
				AllGlobals.code.write(register1,2);
			}
			else if(strcmp(pa_exp->m_strIDname,"&&")==0){
				READTWO
				AllGlobals.code.write("\nand\t",5);
				AllGlobals.code.write(register1,2);
				AllGlobals.code.write(",",1);
				AllGlobals.code.write(register2,2);
				AllGlobals.code.write("\npush\t",6);
				AllGlobals.code.write(register1,2);
			}
			else if(strcmp(pa_exp->m_strIDname,"||")==0){
				READTWO
				AllGlobals.code.write("\nor\t",4);
				AllGlobals.code.write(register1,2);
				AllGlobals.code.write(",",1);
				AllGlobals.code.write(register2,2);
				AllGlobals.code.write("\npush\t",6);
				AllGlobals.code.write(register1,2);
			}
			break;
	}
}

/****************************************************************
**处理除表达式外的其他语句体。
*****************************************************************/
void Cgenerator::generator_substmt(CTreeNode* pa_Stmt){
	//五个静态变量用于保存产生的符号地址。
	static char temp1[41],temp2[41],temp3[41],temp4[41],temp5[41];
	CTreeNode *p;
	switch(pa_Stmt->kind.m_EnStmtKind){
		case IfK:
			generate_stmt(pa_Stmt->m_pchild[0]);
			JUDGE_CONDITION(->)					//判定条件表达式，
			generator_unique_addr(pa_Stmt);	
			strcpy(temp4,pa_Stmt->m_strIDname);
			AllGlobals.code.write(temp4,strlen(temp4));
			generator_unique_addr(pa_Stmt);
			strcpy(temp5,pa_Stmt->m_strIDname);
			AllGlobals.code.write("\njmp\t",5);
			AllGlobals.code.write(temp5,strlen(temp5));
			AllGlobals.code.write("\n",1);
			AllGlobals.code.write(temp4,strlen(temp4));
			AllGlobals.code.write(":\n",2);
			p=pa_Stmt->m_pchild[1];
			while(p){
				generate_stmt(p);
				p=p->m_pbrother;}
			if(pa_Stmt->m_pchild[2]!=NULL){ //如果有else语句。
				generator_unique_addr(pa_Stmt);	
				strcpy(temp4,pa_Stmt->m_strIDname);
				AllGlobals.code.write("\njmp\t",5);
				AllGlobals.code.write(temp4,strlen(temp4));
				AllGlobals.code.write("\n",1);
				AllGlobals.code.write(temp5,strlen(temp5));
				AllGlobals.code.write(":\n",2);
				p=pa_Stmt->m_pchild[2];
				while(p){
					generate_stmt(p);
					p=p->m_pbrother;}
				AllGlobals.code.write("\n",1);
				AllGlobals.code.write(temp4,strlen(temp4));
				AllGlobals.code.write(":\n",2);
			}
			else{
				AllGlobals.code.write("\n",1);
				AllGlobals.code.write(temp5,strlen(temp5));
				AllGlobals.code.write(":\n",2);
			}
			break;
		case WhileK:
			generator_unique_addr(pa_Stmt);	
			strcpy(temp1,pa_Stmt->m_strIDname);
			AllGlobals.code.write("\n",1);
			AllGlobals.code.write(temp1,strlen(temp1));
			AllGlobals.code.write(":\n",2);
			generator_unique_addr(pa_Stmt);	
			strcpy(temp2,pa_Stmt->m_strIDname);
			generate_stmt(pa_Stmt->m_pchild[0]);
			JUDGE_CONDITION(->)
			generator_unique_addr(pa_Stmt);	
			strcpy(temp3,pa_Stmt->m_strIDname);
			AllGlobals.code.write(temp3,strlen(temp3));
			AllGlobals.code.write("\njmp\t",5);
			AllGlobals.code.write(temp2,strlen(temp2));
			AllGlobals.code.write("\n",1);
			AllGlobals.code.write(temp3,strlen(temp3));
			AllGlobals.code.write(":\n",2);
			p=pa_Stmt->m_pchild[1];
			while(p){
				generate_stmt(p);
				p=p->m_pbrother;}
			AllGlobals.code.write("\njmp\t",5);
			AllGlobals.code.write(temp1,strlen(temp1));
			AllGlobals.code.write("\n",1);
			AllGlobals.code.write(temp2,strlen(temp2));
			AllGlobals.code.write(":\n",2);
			break;
		case ForK:
			generate_stmt(pa_Stmt->m_pchild[0]);//for语句的第一个表达式初始化循环计数。
			generator_unique_addr(pa_Stmt);	
			strcpy(temp1,pa_Stmt->m_strIDname);
			generator_unique_addr(pa_Stmt);	
			strcpy(temp2,pa_Stmt->m_strIDname);
			AllGlobals.code.write("\n",1);
			AllGlobals.code.write(temp1,strlen(temp1));
			AllGlobals.code.write(":\n",2);
			generate_stmt(pa_Stmt->m_pchild[0]->m_pbrother);//第二个为条件句。
			JUDGE_CONDITION(->m_pbrother->)
			generator_unique_addr(pa_Stmt);	
			strcpy(temp3,pa_Stmt->m_strIDname);
			AllGlobals.code.write(temp3,strlen(temp3));
			AllGlobals.code.write("\njmp\t",5);
			AllGlobals.code.write(temp2,strlen(temp2));
			AllGlobals.code.write("\n",1);
			AllGlobals.code.write(temp3,strlen(temp3));
			AllGlobals.code.write(":\n",2);
			generate_stmt(pa_Stmt->m_pchild[0]->m_pbrother->m_pbrother);
			p=pa_Stmt->m_pchild[1];
			while(p){
				generate_stmt(p);
				p=p->m_pbrother;}
			AllGlobals.code.write("\njmp\t",5);
			AllGlobals.code.write(temp1,strlen(temp1));
			AllGlobals.code.write("\n",1);
			AllGlobals.code.write(temp2,strlen(temp2));
			AllGlobals.code.write(":\n",2);
			break;
		case WritebK://writeb语句只写一个字符，可直接调用中断进行。
			if(pa_Stmt->m_pchild[0]->kind.m_EnExpKind==ConstK && 
										pa_Stmt->m_pchild[0]->m_EnTypevalue==CCHAR){
				AllGlobals.code.write("\nmov\tah,2h",10);//字符要加单引号，
				AllGlobals.code.write("\nmov\tdl,'",9);
				AllGlobals.code.write(pa_Stmt->m_pchild[0]->m_strIDname,1);
				AllGlobals.code.write("'",1);}
			else if(pa_Stmt->m_pchild[0]->kind.m_EnExpKind==ConstK){
				AllGlobals.code.write("\nmov\tah,2h",10);//数字将作为ascII码值处理。
				AllGlobals.code.write("\nmov\tdl,",8);
				AllGlobals.code.write(pa_Stmt->m_pchild[0]->m_strIDname,
										strlen(pa_Stmt->m_pchild[0]->m_strIDname));}
			else{
				generate_stmt(pa_Stmt->m_pchild[0]);
				AllGlobals.code.write("\npop\tax",7);
				AllGlobals.code.write("\nmov\tah,2h",10);
				AllGlobals.code.write("\nmov\tdx,ax",10);}
				AllGlobals.code.write("\nint\t21h",8);
			break;
		case WritedK://writed只要对参数调用显示例程即可。
			generate_stmt(pa_Stmt->m_pchild[0]);
			AllGlobals.code.write("\nCall\tShow@@Show",16);
			break;
		case GotoK:
			AllGlobals.code.write("\njmp\t",5);
			AllGlobals.code.write(pa_Stmt->m_pchild[0]->m_strIDname,
								strlen(pa_Stmt->m_pchild[0]->m_strIDname));
			break;
		case AddressK:
			AllGlobals.code.write("\n",1);
			AllGlobals.code.write(pa_Stmt->m_pchild[0]->m_strIDname,
										strlen(pa_Stmt->m_pchild[0]->m_strIDname));
			AllGlobals.code.write(":",1);
			break;
		case BreakK://break语句跳到循环控制语句的结尾处。
			AllGlobals.code.write("\njmp\t",5);
			AllGlobals.code.write(temp2,strlen(temp2));
			break;
		case ContinueK://continue语句跳到循环控制语句的起始处。
			AllGlobals.code.write("\njmp\t",5);
			AllGlobals.code.write(temp1,strlen(temp1));
			break;
		case ReturnK:
			if(strcmp(pa_Stmt->m_strScope,"main")!=0)
				AllGlobals.code.write("\npop\tbp",7);
			if(pa_Stmt->m_pchild[0] && strcmp(pa_Stmt->m_strScope,"main")!=0)	
					generate_stmt(pa_Stmt->m_pchild[0]);
			if(pa_Stmt->m_pbrother!=NULL ||//return后面还有语句，则必须写上ret，否则函数结束时
						(pa_Stmt->m_pfather->m_Ennodekind!=FuncK //由函数自己负责。
								&& pa_Stmt->m_pfather->m_pbrother!=NULL)){
				if(strcmp(pa_Stmt->m_strScope,"main")!=0)
						AllGlobals.code.write("\npush\tbp",9);
				AllGlobals.code.write("\nret\n",5);}
			break;
		case CallK:
			p=pa_Stmt->m_pchild[1];
			while(p){
				generate_stmt(p);
				p=p->m_pbrother;}//依次处理函数调用里的所有实参。
			AllGlobals.code.write("\ncall\t",6);
			AllGlobals.code.write(pa_Stmt->m_pchild[0]->m_strIDname,strlen(pa_Stmt->m_pchild[0]->m_strIDname));
			break;
		}
}
				
/****************************************************************
**用于为代码产生唯一的符号地址，符号地址的格式为：
**"作用域＠＠序号"
****************************************************************/
void Cgenerator::generator_unique_addr(CTreeNode *pa_name){
	char temp[5];
	strcpy(pa_name->m_strIDname,pa_name->m_strScope);
	strcat(pa_name->m_strIDname,"@@");
	itoa(m_iunique,temp,5);
	m_iunique++;
	strcat(pa_name->m_strIDname, temp);
}