PL/0编译器(java version) - Interpreter.java
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1: package compiler;
2:
3: import java.io.BufferedReader;
4: import java.io.BufferedWriter;
5: import java.io.IOException;
6: import java.util.Arrays;
7: import java.util.logging.Level;
8: import java.util.logging.Logger;
9:
10:
/**
11:
* 类P-code代码解释器(含代码生成函数)
12:
*
13:
* @author jiangnan
14:
*
15:
*/
16:
public
class Interpreter {
17:
18:
//运行栈上限
19:
private
static final int stackSize = 1000;
20:
//pcode数组上线
21:
private
static final int arraySize = 500;
22:
//虚拟机代码指针，取值范围[0,arraySize-1]
23:
public
int arrayPtr = 0;
24:
//存放虚拟机代码的数组
25:
public Pcode[] pcodeArray;
26:
//显示虚拟代码与否
27:
public
static boolean listswitch = true;
28:
29:
public Interpreter() {
30: pcodeArray = new Pcode[arraySize];
31: }
32:
33:
/**
34:
* 生成虚拟机代码
35:
*
36:
* @param x Pcodeuction.f
37:
* @param y Pcodeuction.l
38:
* @param z Pcodeuction.a
39:
*/
40:
public
void gen(int f, int l, int a) {
41:
if (arrayPtr >= arraySize) { //超出堆栈的上限
42:
throw
new Error("***ERROR:Program too long***");
43: }
44: pcodeArray[arrayPtr++] = new Pcode(f, l, a);
45:
46: }
47:
48:
/**
49:
* 输出目标代码清单
50:
*
51:
* @param start 开始输出的位置
52:
*/
53:
public
void listcode(int start) {
54:
if (listswitch) { //是否显示P-code代码
55:
for (int i = start; i < arrayPtr; i++) {
56:
try {
57: String msg = i + " " + Pcode.pcode[pcodeArray[i].f] + " " + pcodeArray[i].l + " " + pcodeArray[i].a; //形如: lit l,a
58: System.out.println(msg);
59: PL0.pcodeWriter.write(i + " " + msg + ‘\n‘);
60: } catch (Exception e) {
61: e.printStackTrace();
62: System.out.println("***list pcode meet with error***");
63: }
64:
65: }
66: }
67: }
68:
69:
/**
70:
* 这个过程模拟了一台可以运行类PCODE指令的栈式计算机。 它拥有一个栈式数据段用于存放运行期数据, 拥有一个代码段用于存放类PCODE程序代码。
71:
* 同时还拥用数据段分配指针、指令指针、指令寄存器、局部段基址指针等寄存器。
72:
*
73:
* @param stdin 从键盘输入无符号整数
74:
* @param stdout 显示pcode运行过程
75:
*/
76:
public
void interpret(BufferedReader stdin, BufferedWriter stdout) {
77:
int[] runtimeStack = newint[stackSize]; // 程序运行栈
78: Arrays.fill(runtimeStack, 0); //初始化
79: System.out.println("***Start Interpret P_CODE***");
80:
81:
int pc = 0, // pc:指令指针，
82: bp = 0, //bp:指令基址，
83: sp = 0; //sp:栈顶指针
84:
85:
do {
86:
87: Pcode index = pcodeArray[pc++];// index :存放当前指令, 读当前指令
88: System.out.println(pc + " " + Pcode.pcode[index.f] + " " + index.l + " " + index.a);
89:
switch (index.f) {
90:
case Pcode.LIT: // 将a的值取到栈顶
91: runtimeStack[sp++] = index.a;
92:
break;
93:
case Pcode.OPR: // 数学、逻辑运算
94:
switch (index.a) {
95:
case 0: //OPR 0 0;RETURN 返回
96: sp = bp;
97: pc = runtimeStack[sp + 2];
98: bp = runtimeStack[sp + 1];
99:
break;
100:
case 1: //OPR 0 1 ;NEG取反
101: runtimeStack[sp - 1] = -runtimeStack[sp - 1];
102:
break;
103:
case 2: //OPR 0 2;ADD加法
104: sp--;
105: runtimeStack[sp - 1] += runtimeStack[sp];
106:
break;
107:
case 3: //OPR 0 3;SUB减法
108: sp--;
109: runtimeStack[sp - 1] -= runtimeStack[sp];
110:
break;
111:
case 4: //OPR 0 4;MUL乘法
112: sp--;
113: runtimeStack[sp - 1] =runtimeStack[sp - 1] * runtimeStack[sp];
114:
break;
115:
case 5: //OPR 0 5;DIV除法
116: sp--;
117: runtimeStack[sp - 1] /= runtimeStack[sp];
118:
break;
119:
case 6: //OPR 0 6;ODD对2取模mod 2
120: runtimeStack[sp - 1] %= 2;
121:
break;
122:
case 7: //OPR 0 7;MOD取模
123: sp--;
124: runtimeStack[sp - 1] %= runtimeStack[sp];
125:
break;
126:
case 8: //OPR 0 8;==判断相等
127: sp--;
128: runtimeStack[sp - 1] = (runtimeStack[sp] == runtimeStack[sp - 1] ? 1 : 0);
129:
break;
130:
case 9: //OPR 0 9;!=判断不相等
131: sp--;
132: runtimeStack[sp - 1] = (runtimeStack[sp] != runtimeStack[sp - 1] ? 1 : 0);
133:
break;
134:
case 10: //OPR 0 10;<判断小于
135: sp--;
136: runtimeStack[sp - 1] = (runtimeStack[sp] < runtimeStack[sp - 1] ? 1 : 0);
137:
break;
138:
case 11: //OPR 0 11;>=判断大于等于
139: sp--;
140: runtimeStack[sp - 1] = (runtimeStack[sp] >= runtimeStack[sp - 1] ? 1 : 0);
141:
break;
142:
case 12: //OPG 0 12;>判断大于
143: sp--;
144: runtimeStack[sp - 1] = (runtimeStack[sp] > runtimeStack[sp - 1] ? 1 : 0);
145:
break;
146:
case 13: //OPG 0 13;<=判断小于等于
147: sp--;
148: runtimeStack[sp - 1] = (runtimeStack[sp] <= runtimeStack[sp - 1] ? 1 : 0);
149:
break;
150:
case 14: //OPG 0 14;输出栈顶值
151: System.out.println("runtimeStack[sp - 1]" + runtimeStack[sp - 1] + ‘ ‘);
152:
try {
153: stdout.write(" " + runtimeStack[sp - 1] + ‘ ‘);
154: stdout.flush();
155: } catch (Exception ex) {
156: System.out.println("***case 14 meet with error***");
157: }
158: sp--;
159:
break;
160:
case 15: //OPG 0 15;输出换行
161: System.out.print("\n");
162:
try {
163: stdout.write("\n");
164: } catch (Exception ex) {
165: System.out.println("***case 15 meet with error***");
166: }
167:
break;
168:
case 16: //OPG 0 16;读入一行输入，置入栈顶
169: System.out.print("Please Input a Integer : ");
170: runtimeStack[sp] = 0;
171:
try {
172: runtimeStack[sp] = Integer.parseInt(stdin.readLine().trim()); //读入一个整型数字
173: System.out.println(runtimeStack[sp]);
174: sp++;
175: } catch (Exception e) {
176: e.printStackTrace();
177: System.out.println("***read data meet with error***");
178: }
179:
try {
180: stdout.write(" " + runtimeStack[sp] + ‘\n‘);
181: stdout.flush();
182: } catch (Exception ex) {
183: System.out.println("***case 16 meet with error***");
184: }
185:
break;
186: }
187:
break;
188:
case Pcode.LOD: //取相对当前过程的数据基地址为a的内存的值到栈顶
189: runtimeStack[sp] = runtimeStack[base(index.l, runtimeStack, bp) + index.a];
190: sp++;
191:
break;
192:
case Pcode.STO: //栈顶的值存到相对当前的过程的数据基地址为a的内存
193: sp--;
194: runtimeStack[base(index.l, runtimeStack, bp) + index.a] = runtimeStack[sp];
195:
break;
196:
case Pcode.CAL: //调用子程序
197: runtimeStack[sp] = base(index.l, runtimeStack, bp); //将静态作用域基地址入栈
198: runtimeStack[sp + 1] = bp; //将动态作用域基地址
199: runtimeStack[sp + 2] = pc; //将当前指针入栈
200: bp = sp; //改变基地址指针值为新过程的基地址
201: pc = index.a; //跳转至地址a
202:
break;
203:
case Pcode.INT: //开辟空间大小为a
204: sp += index.a;
205:
break;
206:
case Pcode.JMP: //直接跳转至a
207: pc = index.a;
208:
break;
209:
case Pcode.JPC:
210: sp--;
211:
if (runtimeStack[sp] == 0) //条件跳转至a(当栈顶指针为0时)
212: {
213: pc = index.a;
214: }
215:
break;
216: }
217: } while (pc != 0);
218: }
219:
220:
/**
221:
* 通过给定的层次差来获得该层的堆栈帧基址
222:
*
223:
* @param l 目标层次与当前层次的层次差
224:
* @param runtimeStack 运行栈
225:
* @param b 当前层堆栈帧基地址
226:
* @return 目标层次的堆栈帧基地址
227:
*/
228:
private
int
base(int l, int[] runtimeStack, int b) {
229:
while (l > 0) { //向上找l层
230: b = runtimeStack[b];
231: l--;
232: }
233:
return b;
234: }
235:
236:
public
void debugPcodeArray() throws IOException {
237: System.out.println("***Auto-Generated Pcode Array***");
238: String msg = null;
239:
for (int i = 0; pcodeArray[i] != null; i++) {
240: msg = "" + i + " " + Pcode.pcode[pcodeArray[i].f] + " " + pcodeArray[i].l + " " + pcodeArray[i].a;
241: System.out.println(msg);
242: PL0.pcodeWriter.write(msg + ‘\n‘);
243: }
244: }
245: }
原文：http://www.cnblogs.com/ZJUT-jiangnan/p/3560950.html
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