📄 unit1.~cpp
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}
GEN(OPR,0,15);//OPR 0 15 屏幕输出换行
break; /*WRITESYM*/
case CALLSYM: //CALL语句
GetSym();
if (SYM!=IDENT) Error(14); //CALL后应是标识符
else {
i=POSITION(ID,TX); //在符号表中返回符号的位置
if (i==0) Error(11); //标识符未说明
else
if (TABLE[i].KIND==PROCEDUR)
//CAL L A 调用过程,A为过程地址,L为层差
GEN(CAL,LEV-TABLE[i].vp.LEVEL,TABLE[i].vp.ADR);
else Error(15); //CALL后标识符属性应为过程
GetSym();
}
break;
case IFSYM: //IF语句
GetSym();
CONDITION(SymSetUnion(SymSetNew(THENSYM,DOSYM),FSYS),LEV,TX);
if (SYM==THENSYM)
GetSym();
else Error(16); // 条件语句丢了'then'
CX1=CX;
GEN(JPC,0,0); //JPC 0 A 条件跳转,当栈顶布尔值非真则跳转到A地址,否则顺序执行
//ELSE语句改造开始---------------------------------------------
STATEMENT(SymSetUnion(SymSetNew(ELSESYM),FSYS),LEV,TX);
if(SYM!=ELSESYM)
CODE[CX1].A=CX;
else{
CX2=CX;
GEN(JMP,0,0);
CODE[CX1].A=CX;
GetSym();
STATEMENT(FSYS,LEV,TX);
CODE[CX2].A=CX;
}
//ELSE语句改造结束--------------------------------------------------
break;
case BEGINSYM: //BEGIN语句
GetSym();
STATEMENT(SymSetUnion(SymSetNew(SEMICOLON,ENDSYM),FSYS),LEV,TX);
while (SymIn(SYM, SymSetAdd(SEMICOLON,STATBEGSYS))) {
if (SYM==SEMICOLON) GetSym(); //';'号
else Error(10); //语句间漏了';'
STATEMENT(SymSetUnion(SymSetNew(SEMICOLON,ENDSYM),FSYS),LEV,TX);
}
if (SYM==ENDSYM) GetSym();
else Error(17); //丢了'end'或';'
break;
case WHILESYM: //WHILE语句
CX1=CX; GetSym(); CONDITION(SymSetAdd(DOSYM,FSYS),LEV,TX);
CX2=CX;
GEN(JPC,0,0);//JPC 0 A 条件跳转,当栈顶布尔值非真则跳转到A地址,否则顺序执行
if (SYM==DOSYM) GetSym();
else Error(18); //WHILE型循环语句丢了'do'
STATEMENT(FSYS,LEV,TX);
GEN(JMP,0,CX1);//JPC 0 A 条件跳转,当栈顶布尔值非真则跳转到A地址,否则顺序执行
CODE[CX2].A=CX;
break;
//FOR改造================================================================================
case FORSYM:
GetSym(); //<变量>:=<表达式>
if (SYM!=IDENT) Error(14); //CALL后应是标识符
else {
i=POSITION(ID,TX); //TX:符号表的下标变量,在符号表中返回符号ID的位置
if (i==0) Error(11); //标识符未说明
else if (TABLE[i].KIND!=VARIABLE) { //对比类型属性是否为变量
Error(12); i=0; //赋值语句中,赋值号左部标识符属性应是变量
}
GetSym();
if (SYM==BECOMES) GetSym();
else Error(13); //赋值语句左部标识符后应是赋值号":=" //
EXPRESSION(SymSetUnion(SymSetNew(TOSYM,DOWNTOSYM),FSYS),LEV,TX);
if (i!=0){//STO L A 将栈顶内容送入某一变量单元中,A为偏移量,L为层差
GEN(STO,LEV-TABLE[i].vp.LEVEL,TABLE[i].vp.ADR);
CX1=CX;
GEN(LOD,LEV-TABLE[i].vp.LEVEL,TABLE[i].vp.ADR);
SYM1=SYM;
} //放到次栈顶
//GetSym();
if(SYM==TOSYM||SYM==DOWNTOSYM) {
GetSym();
EXPRESSION(SymSetUnion(SymSetNew(DOSYM),FSYS),LEV,TX);
if(SYM1==TOSYM)
GEN(OPR,0,13);//TOSYM 次栈顶是否<=栈顶,退两个栈元素,结果值进栈 ,若<=时,则顺序执行
else if(SYM1==DOWNTOSYM)
GEN(OPR,0,11);//DOWNTO 次栈顶是否>=栈顶,退两个栈元素,结果值进栈 ,若>=时,则顺序执行
//GEN(OPR,0,13);//次栈顶是否小于栈顶,退两个栈元素,结果值进栈
CX2=CX;
GEN(JPC,0,0);//JPC 0 A 条件跳转,当栈顶布尔值非真则跳转到A地址,否则顺序执行
GetSym();
STATEMENT(FSYS,LEV,TX);
if (i!=0){//STO L A 将栈顶内容送入某一变量单元中,A为偏移量,L为层差
GEN(LOD,LEV-TABLE[i].vp.LEVEL,TABLE[i].vp.ADR);
GEN(LIT,0,1);
if(SYM1==TOSYM) GEN(OPR,0,2); //次栈顶与栈顶相加,退两个栈元素,结果值进栈
else if(SYM1==DOWNTOSYM) GEN(OPR,0,3);//次栈顶减去栈顶,退两个栈元素,结果值进栈
GEN(STO,LEV-TABLE[i].vp.LEVEL,TABLE[i].vp.ADR);
} //放到次栈顶
GEN(JMP,0,CX1);
}
else Error(25);
}
CODE[CX2].A=CX;
break;
//========================================================================
}
TEST(FSYS,SymSetNULL(),19);
} /*STATEMENT*/
//---------------------------------------------------------------------------
void Block(int LEV, int TX, SYMSET FSYS) { /*分程序分析处理过程*/
/* LEV:嵌套层的层数,在C主函数中设为0
TX:索引表的指针,表中的每个元素为记录型数据
FSYS:单词符号集合
*/
int DX=3; /*地址指示器*/
int TX0=TX; /*INITIAL TABLE INDEX*/
int CX0=CX; /*INITIAL CODE INDEX*/
TABLE[TX].vp.ADR=CX; GEN(JMP,0,0);
if (LEV>LEVMAX) Error(32); //层数超过了预定的则出错
do {
if (SYM==CONSTSYM) { //若是常量,则进行常量处理
GetSym();
do {
ConstDeclaration(LEV,TX,DX);
while (SYM==COMMA) {
GetSym(); ConstDeclaration(LEV,TX,DX);
}
if (SYM==SEMICOLON) GetSym(); //过滤';'
else Error(5); //漏了','或';'
}while(SYM==IDENT);
}
if (SYM==VARSYM) { //若是变量,则进行变量处理
GetSym();
do {
VarDeclaration(LEV,TX,DX);
while (SYM==COMMA) { GetSym(); VarDeclaration(LEV,TX,DX); }
if (SYM==SEMICOLON) GetSym();
else Error(5); //漏了','或';'
}while(SYM==IDENT);
}
//CHAR 改造开始-------------------------------------------------------------------------------
if (SYM==CHARSYM) { //若是字符,则进行字符处理
GetSym();
do {
CharDeclaration(LEV,TX,DX);
while (SYM==COMMA) { GetSym(); CharDeclaration(LEV,TX,DX); }
if (SYM==SEMICOLON) GetSym();
else Error(5); //漏了','或';'
}while(SYM==IDENT);
}
//CHAR 改造结束----------------------------------------------------------------------------------
while ( SYM==PROCSYM) { //若是过程,则进行过程处理
GetSym();
if (SYM==IDENT) { ENTER(PROCEDUR,LEV,TX,DX); GetSym(); }
else Error(4); //const,var,procedure 后应为标识符
if (SYM==SEMICOLON) GetSym();
else Error(5); //漏了';'号
Block(LEV+1,TX,SymSetAdd(SEMICOLON,FSYS)); //凋用递归,LEV+1
if (SYM==SEMICOLON) {
GetSym();
TEST(SymSetUnion(SymSetNew(IDENT,PROCSYM),STATBEGSYS),FSYS,6);
}
else Error(5); //漏了';'号
}
TEST(SymSetAdd(IDENT,STATBEGSYS), DECLBEGSYS,7);
}while(SymIn(SYM,DECLBEGSYS));
CODE[TABLE[TX0].vp.ADR].A=CX;
TABLE[TX0].vp.ADR=CX; /*数据段开始地址*/
TABLE[TX0].vp.SIZE=DX; /*数据的容量*/ //主要是为了存放调用的地址, 为回填数据
GEN(INI,0,DX); //开辟数据段
STATEMENT(SymSetUnion(SymSetNew(SEMICOLON,ENDSYM),FSYS),LEV,TX);
GEN(OPR,0,0); /*生成退出数据段指令*/
TEST(FSYS,SymSetNULL(),8); //测试SYM是否为语句的后跟符
ListCode(CX0);
} /*Block*/
//---------------------------------------------------------------------------
int BASE(int L,int B,int S[]) { /*通过静态链求出数据区的基地址*/
int B1=B; /*FIND BASE L LEVELS DOWN*/
while (L>0) { B1=S[B1]; L=L-1; }
return B1;
} /*BASE*/
//---------------------------------------------------------------------------
void Interpret() { /*对目标代码的解释执行程序*/
/*
I:指令寄存器.存放当前正在解释的一条目标指令.
P:程序地址寄存器.指向下一条要执行的目标程序的地址(相当目标程序CODE数组的下标).
T:栈顶寄存器.由于每个过程当它被运行时.给它分配的数据空间(下边称数据段)分成两两部分.
B:基址寄存器.
SL:静态链:它是指向定义该过程的直接外过程(或主程序)运行时最新数据段的基地址
DL:动态链:它是指向调用该过程正在运行过程的数据段基地址.
RA:返回地址:记录调用该过程时目标程序的数点.即当时的程序地址寄存器P的
*/
const STACKSIZE = 500;
String temp;
bool btemp=false;
int count=0;
int P,B,T; /*PROGRAM BASE TOPSTACK REGISTERS*/
INSTRUCTION I;
int S[STACKSIZE]; /*DATASTORE*/
Form1->printfs("----------------------------- RUN PL0 ----------------------------- ");
fprintf(FOUT,"----------------------------- RUN PL0 ----------------------------- \n");
T=0; B=1; P=0;
S[1]=0; S[2]=0; S[3]=0;
do {
I=CODE[P]; P=P+1;
switch (I.F) {
case LIT: T++; S[T]=I.A; break;
case OPR:
switch (I.A) { /*OPERATOR*/
case 0: /*RETURN*/ T=B-1; P=S[T+3]; B=S[T+2]; break;
case 1: S[T]=-S[T]; break;
case 2: T--; S[T]=S[T]+S[T+1]; break;
case 3: T--; S[T]=S[T]-S[T+1]; break;
case 4: T--; S[T]=S[T]*S[T+1]; break;
case 5: T--; S[T]=S[T] % S[T+1]; break;
case 6: S[T]=(S[T]%2!=0); break;
case 8: T--; S[T]=S[T]==S[T+1]; break;
case 9: T--; S[T]=S[T]!=S[T+1]; break;
case 10: T--; S[T]=S[T]<S[T+1]; break;
case 11: T--; S[T]=S[T]>=S[T+1]; break;
case 12: T--; S[T]=S[T]>S[T+1]; break;
case 13: T--; S[T]=S[T]<=S[T+1]; break;
case 14: Form1->printls("",S[T]); fprintf(FOUT,"%d\n",S[T]); T--;
break;
case 15: /*Form1->printfs(""); fprintf(FOUT,"\n"); */ break;
case 16: T++;
temp=InputBox("输入","请键盘输入：", 0);
count=temp.Length();
while(count>0)
{
if(temp[count]<'0'||temp[count]>'9'){
btemp=true;
break;
}
count--;
}
if(!btemp) S[T]=temp.ToInt();
else {
S[T]=(int)temp[1];//InputBox("输入","请键盘输入：", 0).ToInt();
}
Form1->printls("? ",S[T]); fprintf(FOUT,"? %d\n",S[T]);
break;
}
break;
case LOD: T++; S[T]=S[BASE(I.L,B,S)+I.A]; break;
case STO: S[BASE(I.L,B,S)+I.A]=S[T]; T--; break;
case CAL: /*GENERAT NEW Block MARK*/
S[T+1]=BASE(I.L,B,S); S[T+2]=B; S[T+3]=P;
B=T+1; P=I.A; break;
case INI: T=T+I.A; break;
case JMP: P=I.A; break;
case JPC: if (S[T]==0) P=I.A; T--; break;
} /*switch*/
}while(P!=0);
Form1->printfs("----------------------------- END PL0 -----------------------------");
fprintf(FOUT,"------------------------- END PL0 -----------------------------\n");
} /*Interpret*/
//---------------------------------------------------------------------------
void __fastcall TForm1::ButtonRunClick(TObject *Sender) {
for (CH=' '; CH<='^'; CH++)
SSYM[CH]=NUL; //字符表从' '到'^'即只有大写
strcpy(KWORD[ 1],"BEGIN"); strcpy(KWORD[ 2],"CALL");
strcpy(KWORD[ 3],"CHAR");
strcpy(KWORD[ 4],"CONST"); strcpy(KWORD[ 5],"DO");
strcpy(KWORD[ 6],"DOWNTO");
strcpy(KWORD[ 7],"ELSE");
strcpy(KWORD[ 8],"END");
strcpy(KWORD[ 9],"FOR");
strcpy(KWORD[10],"IF"); strcpy(KWORD[11],"ODD");
strcpy(KWORD[12],"PROCEDURE");strcpy(KWORD[13],"PROGRAM");
strcpy(KWORD[14],"READ"); strcpy(KWORD[15],"THEN");
strcpy(KWORD[16],"TO");
strcpy(KWORD[17],"VAR"); strcpy(KWORD[18],"WHILE");
strcpy(KWORD[19],"WRITE");
WSYM[ 1]=BEGINSYM; WSYM[ 2]=CALLSYM;
WSYM[ 3]=CHARSYM;
WSYM[ 4]=CONSTSYM; WSYM[ 5]=DOSYM;
WSYM[ 6]=DOWNTOSYM;
WSYM[ 7]=ELSESYM;
WSYM[ 8]=ENDSYM;
WSYM[ 9]=FORSYM;
WSYM[10]=IFSYM; WSYM[11]=ODDSYM;
WSYM[12]=PROCSYM; WSYM[13]=PROGSYM;
WSYM[14]=READSYM; WSYM[15]=THENSYM;
WSYM[16]=TOSYM;
WSYM[17]=VARSYM; WSYM[18]=WHILESYM;
WSYM[19]=WRITESYM;
//SSYM['+']=PLUS; SSYM['-']=MINUS; 删除
SSYM['*']=TIMES; SSYM['/']=SLASH;
SSYM['(']=LPAREN; SSYM[')']=RPAREN;
SSYM['=']=EQL; SSYM[',']=COMMA;
SSYM['.']=PERIOD; //SSYM['#']=NEQ; 删除
SSYM[';']=SEMICOLON;
SSYM['\'']=QUOT;
strcpy(MNEMONIC[LIT],"LIT"); strcpy(MNEMONIC[OPR],"OPR");
strcpy(MNEMONIC[LOD],"LOD"); strcpy(MNEMONIC[STO],"STO");
strcpy(MNEMONIC[CAL],"CAL"); strcpy(MNEMONIC[INI],"INI");
strcpy(MNEMONIC[JMP],"JMP"); strcpy(MNEMONIC[JPC],"JPC");
DECLBEGSYS=(int*)malloc(sizeof(int)*NumOfSybol);
STATBEGSYS=(int*)malloc(sizeof(int)*NumOfSybol);
FACBEGSYS =(int*)malloc(sizeof(int)*NumOfSybol);
for(int j=0; j<NumOfSybol; j++) {
DECLBEGSYS[j]=0; STATBEGSYS[j]=0; FACBEGSYS[j] =0;
}
DECLBEGSYS[CHARSYM]=1;
DECLBEGSYS[CONSTSYM]=1;
DECLBEGSYS[VARSYM]=1;
DECLBEGSYS[PROCSYM]=1;
STATBEGSYS[BEGINSYM]=1;
STATBEGSYS[CALLSYM]=1;
STATBEGSYS[IFSYM]=1;
STATBEGSYS[WHILESYM]=1;
STATBEGSYS[WRITESYM]=1;
FACBEGSYS[IDENT] =1;
FACBEGSYS[NUMBER]=1;
FACBEGSYS[LPAREN]=1;
if ((FIN=fopen((Form1->EditName->Text+".PL0").c_str(),"r"))!=0) {
FOUT=fopen((Form1->EditName->Text+".COD").c_str(),"w");
Form1->printfs("=== COMPILE PL0 ===");
fprintf(FOUT,"=== COMPILE PL0 ===\n");
ERR=0;
CC=0; CX=0; LL=0; CH=' '; GetSym();
if (SYM!=PROGSYM) Error(0);
else {
GetSym();
if (SYM!=IDENT) Error(0);
else {
GetSym();
if (SYM!=SEMICOLON) Error(5);
else GetSym();
}
}
Block(0,0,SymSetAdd(PERIOD,SymSetUnion(DECLBEGSYS,STATBEGSYS)));
if (SYM!=PERIOD) Error(9);
if (ERR==0) Interpret();
else {
Form1->printfs("ERROR IN PL/0 PROGRAM");
fprintf(FOUT,"ERROR IN PL/0 PROGRAM");
}
fprintf(FOUT,"\n"); fclose(FOUT);
}
}
//---------------------------------------------------------------------------
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