Added support for Strings

src/main/asm/chocopy/common/allChars.s

@@ -0,0 +1,2 @@
+.space 5120
+    .text

src/main/asm/chocopy/common/initchars.s

@@ -0,0 +1,22 @@
+       la a0, $str$prototype
+        lw t0, 0(a0)
+        lw t1, 4(a0)
+        lw t2, 8(a0)
+        li t3, 1
+        la a0, allChars
+        li t4, 256
+        mv t5, zero
+initchars_1:
+        sw t0, 0(a0)
+        sw t1, 4(a0)
+        sw t2, 8(a0)
+        sw t3, 12(a0)
+        sw t5, 16(a0)
+        addi a0, a0, 20
+        addi t5, t5, 1
+        bne t4, t5, initchars_1
+        jr  ra
+        .data
+        .align 2
+
+        

src/main/java/chocopy/pa3/CodeGenImpl.java

@@ -39,8 +39,8 @@ public class CodeGenImpl extends CodeGenBase
     protected final Label strcatLabel = new Label("strcat");
     protected final Label concatLabel = new Label("concat");
     protected final Label conslistLabel = new Label("conslist");
-
+    protected final Label initcharsLabel = new Label("initchars");  
-
+    protected final Label allCharsLabel = new Label("allChars");
       
 
     /** Operation on None. */
@@ -86,7 +86,7 @@ public class CodeGenImpl extends CodeGenBase
         backend.emitSW(ZERO, SP, 0, "Top saved FP is 0.");
         backend.emitSW(ZERO, SP, 4, "Top saved RA is 0.");
         backend.emitADDI(FP, SP, 2 * backend.getWordSize(), "Set FP to previous SP.");
-
+        backend.emitJAL(initcharsLabel,"Initialize one-character strings");
         for (Stmt stmt : statements) 
         {
             stmt.dispatch(stmtAnalyzer);
@@ -1008,7 +1008,7 @@ public class CodeGenImpl extends CodeGenBase
                 r=getRegister();
                 regs.add(r);
                 Register iter = registerPool[r];
-                backend.emitSW(l, Register.FP, -sp_off*wordSize, "Store index on stack");
+                backend.emitSW(l, Register.FP, -sp_off*wordSize, "Store location on stack");
                 incSp(1);
                 backend.emitMV(iter, Register.ZERO, "Initialize index variable");
                 backend.emitSW(iter, Register.FP, -sp_off*wordSize, "Store index on stack");
@@ -1048,6 +1048,7 @@ public class CodeGenImpl extends CodeGenBase
             {
                 Label startLoop = generateLocalLabel();
                 Label endLoop = generateLocalLabel();
+                //Label temp = generateLocalLabel();
                 r=getRegister();
                 regs.add(r);
                 Register iden = registerPool[r];
@@ -1058,17 +1059,33 @@ public class CodeGenImpl extends CodeGenBase
                 r=getRegister();
                 regs.add(r);
                 Register ln = registerPool[r];
+                //backend.emitBNEZ(Register.A0, temp, "Ensure not none");
+                //backend.emitJ(errorNone, "Empty String");
+                //backend.emitLocalLabel(temp, "Continue execution for for-loop");
                 backend.emitMV(l,Register.A0,"Location of String");
                 r=getRegister();
                 regs.add(r);
                 Register iter = registerPool[r];
+                backend.emitSW(l, Register.FP, -sp_off*wordSize, "Store location on stack");
+                incSp(1);
                 backend.emitMV(iter, Register.ZERO, "Initialize index variable");
+                backend.emitSW(iter, Register.FP, -sp_off*wordSize, "Store index on stack");
+                incSp(1);
                 backend.emitLocalLabel(startLoop, "Start for loop");
+                backend.emitLW(iter, Register.FP, -(sp_off-1)*wordSize, "Load index from stack");
+                backend.emitLW(l, Register.FP, -(sp_off-2)*wordSize, "Store string location from stack");
                 backend.emitLW(ln, l, getAttrOffset(strClass, "__len__"), "Get attribute __len__");
-                backend.emitBGE(iter, ln, endLoop, "Jump to end loop if counter exceeds length");
+                backend.emitBGEU(iter, ln, endLoop, "Jump to end loop if counter exceeds length");
-                
+                backend.emitADDI(iter, iter, 1, "Increment counter");
+                backend.emitSW(iter, Register.FP, -sp_off*wordSize, "Store index on stack");
+                incSp(1);
                 backend.emitADDI(iden, iter, 4 * wordSize, "Convert index to offset to char in bytes");
+                backend.emitADD(iden, l, iden, "Get pointer to char");
                 backend.emitLBU(iden, iden, 0, "Load character");
+                backend.emitLI(iter, 20, "Load register");
+                backend.emitMUL(iden, iden, iter, "Multiply by size of String object");
+                backend.emitLA(l, allCharsLabel, "Index into single-char table");
+                backend.emitADD(l, l, iden, "Add size to chartable index");
                 SymbolInfo info = sym.get(node.identifier.name);
                 if(info instanceof GlobalVarInfo)
                 {
@@ -1083,7 +1100,6 @@ public class CodeGenImpl extends CodeGenBase
                 }
                 for(Stmt stmt:node.body)
                     stmt.dispatch(this);
-                backend.emitADDI(iter, iter, 1, "Increment counter");
                 backend.emitJ(startLoop, "Jump to beginning of loop");
                 backend.emitLocalLabel(endLoop, "End of for loop");
             } 
@@ -1196,6 +1212,8 @@ public class CodeGenImpl extends CodeGenBase
         emitStdFunc("strneql");
         emitStdFunc("makeint");
         emitStdFunc("makebool");
+        emitStdFunc("initchars");
+        emitStdFunc("allChars");
 
         emitErrorFunc(errorNone, "Operation on None");
         emitErrorFunc(errorDiv, "Division by zero");