Add support for pointers of char, int and long types

include/Data.h

@@ -16,6 +16,8 @@
 
 extern_ struct SymbolTable Symbols[SYMBOLS];
 
+extern_ char* TypeNames[9];
+
 extern_ char* TokenStrings[];
 extern_ char* TokenNames[];
 

include/Defs.h

@@ -16,6 +16,7 @@
  * TYpes are prefixed TY.
  * CoMParisons are prefixed CMP.
  * 
+ * 
  * NOTE: Tokens are different from Syntax Operations!
  * 
  * Tokens should represent the characters that invoke them,
@@ -49,6 +50,8 @@ enum TokenTypes {
     LI_LPARE,       // (
     LI_RPARE,       // )
 
+    LI_AMP,         // &
+
     TY_IDENTIFIER,  // Identifier name. Variable, function, etc.
     TY_NONE,        // No return type. Literal void.
     TY_CHAR,        // "char" type keyword
@@ -94,6 +97,9 @@ enum SyntaxOps {
 
     OP_ASSIGN,          // Assign an l-value
 
+    OP_ADDRESS,         // Fetch the address of a var
+    OP_DEREF,           // Get the value of the address in a pointer
+
     TERM_INTLITERAL,    // Integer Literal. This is a virtual operation, so it's a terminal.
 
     REF_IDENT,          // Reference (read) an identifier (variable).
@@ -149,11 +155,17 @@ struct SymbolTable {
  * //TODO: Move back into TokenTypes
  */
 enum DataTypes {
-    RET_NONE,        // No return type. Literal void.
+    RET_NONE,       // No return type. Literal void.
-    RET_CHAR,        // "char" type keyword
+    RET_CHAR,       // "char" type keyword
-    RET_INT,         // "int" type keyword
+    RET_INT,        // "int" type keyword
-    RET_LONG,        // "long" type keyword
+    RET_LONG,       // "long" type keyword
-    RET_VOID,        // "void" type keyword
+    RET_VOID,       // "void" type keyword
+
+                    // Pointer types
+    PTR_CHAR,
+    PTR_INT,
+    PTR_LONG,
+    PTR_VOID,       
 
 };
 
@@ -212,8 +224,10 @@ struct ASTNode* ParsePrecedenceASTNode(int PreviousTokenPrecedence);
 
 int ParseAST(struct ASTNode* Node);
 
+struct ASTNode* ParsePrimary(void);
 //void ParseStatements(void);
 struct ASTNode* ParseStatement(void);
+struct ASTNode* PrefixStatement();
 
 struct ASTNode* ParseFunction();
 struct ASTNode* ParseCompound();
@@ -222,7 +236,9 @@ struct ASTNode* ParseCompound();
 struct ASTNode* CallFunction();
 struct ASTNode* ReturnStatement();
 
-int ParseType(int Token);
+int ParsePointer();
+int ValueAt(int Type);
+int PointerTo(int Type);
 
 
 int ParseTokenToOperation(int Token);
@@ -279,6 +295,9 @@ int AsDiv(int Left, int Right);
 int AsLdVar(int ID);
 int AsStrVar(int Register, int ID);
 
+int AsDeref(int Reg, int Type);
+int AsAddr(int ID);
+
 void AsNewSymb(int ID);
 
 int AsEqual(int Left, int Right);

src/Assembler.c

@@ -26,8 +26,6 @@ static char* ByteRegisters[4]   = { "%r8b", "%r9b", "%r10b", "%r11b" };
 static char* Comparisons[6]     = { "sete", "setne", "setl", "setg", "setle", "setge" };
 static char* InvComparisons[6]  = { "jne", "je",     "jge",  "jle",  "jg",    "jl"};
 
-static char* Types[5]           = { "none", "char", "int", "long", "void" };
-
 /* * * * * * * * * * * * * * * * * * * * * * * * * * * *
  * * * *   R O O T    O F    A S S E M B L E R   * * * *
  * * * * * * * * * * * * * * * * * * * * * * * * * * * */
@@ -85,6 +83,12 @@ int AssembleTree(struct ASTNode* Node, int Register, int ParentOp) {
         case OP_DIVIDE:
             return AsDiv(LeftVal, RightVal);
             
+        case OP_ADDRESS:
+            return AsAddr(Node->Value.ID);
+
+        case OP_DEREF:
+            return AsDeref(LeftVal, Node->Left->ExprType);
+
         case OP_ASSIGN:
             return RightVal;
 
@@ -356,18 +360,22 @@ int AsLdVar(int ID) {
             break;
         
         case RET_LONG:
+        case PTR_CHAR:
+        case PTR_INT:
+        case PTR_LONG:
+        case PTR_VOID:
             fprintf(OutputFile, "\tmovq\t%s(%%rip), %s\n", Symbols[ID].Name, Registers[Reg]);
             break;
 
         default:
-            DieMessage("Bad type for loading", Types[Symbols[ID].Type]);
+            DieMessage("Bad type for loading", TypeNames[Symbols[ID].Type]);
     }
 
     return Reg;
 }
 
 int AsStrVar(int Register, int ID) {
-    printf("\tStoring contents of %s into %s\n", Registers[Register], Symbols[ID].Name);
+    printf("\tStoring contents of %s into %s, type %d\n", Registers[Register], Symbols[ID].Name, Symbols[ID].Type);
 
     switch(Symbols[ID].Type) {
         case RET_CHAR:
@@ -380,16 +388,44 @@ int AsStrVar(int Register, int ID) {
             break;
         
         case RET_LONG:
+        case PTR_CHAR:
+        case PTR_INT:
+        case PTR_LONG:
+        case PTR_VOID:
             fprintf(OutputFile, "\tmovq\t%s, %s(%%rip)\n", Registers[Register], Symbols[ID].Name);
             break;
 
         default:
-            DieMessage("Bad type for saving", Types[Symbols[ID].Type]);
+            DieMessage("Bad type for saving", TypeNames[Symbols[ID].Type]);
     }
     
     return Register;
 }
 
+int AsAddr(int ID) {
+    int Register = RetrieveRegister();
+    printf("\tSaving pointer of %s into %s\n", Symbols[ID].Name, Registers[Register]);
+
+    fprintf(OutputFile, "\tleaq\t%s(%%rip), %s\n", Symbols[ID].Name, Registers[Register]);
+    return Register;
+}
+
+int AsDeref(int Reg, int Type) {
+
+    printf("\tDereferencing %s\n", Registers[Reg]);
+    switch(Type) {
+        case PTR_CHAR:
+            fprintf(OutputFile, "\tmovzbq\t(%s), %s\n", Registers[Reg], Registers[Reg]);
+            break;
+        case PTR_INT:
+        case PTR_LONG:
+            fprintf(OutputFile, "\tmovq\t(%s), %s\n", Registers[Reg], Registers[Reg]);
+            break;
+    }
+
+    return Reg;
+}
+
 void AsNewSymb(int ID) {
     int TypeSize;
 
@@ -432,7 +468,7 @@ int AsReturn(int Register, int FuncID) {
             break;
         
         default:
-            DieMessage("Bad function type in generating return", Types[Symbols[FuncID].Type]);
+            DieMessage("Bad function type in generating return", TypeNames[Symbols[FuncID].Type]);
 
     }
 

src/Lexer.c

@@ -219,6 +219,10 @@ int Tokenise(struct Token* Token) {
             Token->type = AR_SLASH;
             break;
 
+        case '&':
+            Token->type = LI_AMP;
+            break;
+        
         case '=':
             Char = NextChar();
             // If the next char is =, we have ==, the compare equality token.

src/Main.c

@@ -35,6 +35,8 @@ char* TokenNames[] = {
     "Logical Block Start",
     "Logical Block End",
 
+    "Dereference operator",
+
     "Identifier",
     "None Type",
     "Char Type",
@@ -52,21 +54,8 @@ char* TokenNames[] = {
     "Return keyword"
 };
 
-static void TokeniseFile() {
+char* TypeNames[9]  = { "none", "char", "int", "long", "void", "charptr", "intptr", "longptr", "voidptr"};
 
-    struct Token Token;
-
-    while(Tokenise(&Token)) {
-
-        printf("Token %s", TokenStrings[Token.type]);
-        if(Token.type == LI_INT) {
-            printf(", value %d", Token.value);
-        }
-
-        printf("\n");
-    }
-    
-}
 
 int main(int argc, char* argv[]) {
     Line = 1;

src/Parser.c

@@ -99,7 +99,7 @@ int ParseTokenToOperation(int Token) {
  * 
  */
 
-static struct ASTNode* ParsePrimary(void) {
+struct ASTNode* ParsePrimary(void) {
     struct ASTNode* Node;
     int ID;
 
@@ -174,7 +174,7 @@ struct ASTNode* ParsePrecedenceASTNode(int PreviousTokenPrecedence) {
     int LeftType, RightType;
     int NodeType;
 
-    LeftNode = ParsePrimary();
+    LeftNode = PrefixStatement();
 
     NodeType = CurrentToken.type;
     if(NodeType == LI_SEMIC || NodeType == LI_RPARE)

src/Pointers.c

@@ -0,0 +1,66 @@
+
+/*************/
+/*GEMWIRE    */
+/*    ERYTHRO*/
+/*************/
+
+#include <Defs.h>
+#include <Data.h>
+
+int PointerTo(int Type) {
+
+    printf("\t\tPointerising a %s\n", TypeNames[Type]);
+    // As it stands, the conversion between
+    // RET and PTR is +4.
+    // TODO: if we add types, increase this number
+    // TODO: Make this a proper translation table
+    // TODO: More checks! This can go wrong easily!
+    if(Type >= RET_CHAR && Type <= RET_VOID) {
+        return Type + 4;
+    } else {
+        DieDecimal("Unable to create a pointer to the desired type", Type);
+    }
+
+    return -1;
+}
+
+int ValueAt(int Type) {
+
+    printf("\t\tDereferencing a %s\n", TypeNames[Type]);
+    //TODO: this is still bullshittery!
+    if(Type >= PTR_CHAR && Type <= PTR_VOID) {
+        return Type - 4;
+    } else {
+        DieDecimal("Unable to dereference type", Type);
+    }
+    return -1;
+}
+
+int ParsePointer() {
+
+    int Type;
+    // TODO: THIS IS WRONG AND SHOULD NOT EXIST
+    // TY_CHAR is 21, RET_CHAR is 1.
+    // Offset is 20. Rest are in order
+
+    if(CurrentToken.type >= TY_CHAR && CurrentToken.type <= TY_VOID) {
+        Type = CurrentToken.type - 20;
+    } else {
+        DieDecimal("Illegal type for pointerisation", CurrentToken.type);
+    }
+    // Recursively scan more *s
+    // This makes things like:
+    // x = **y;
+    // possible.
+    while(1) {
+        Tokenise(&CurrentToken);
+        printf("\t\t\tType on parsing is %d\n", CurrentToken.type);
+        if(CurrentToken.type != AR_STAR)
+            break;
+        
+        Type = PointerTo(Type);
+    }
+
+    return Type;
+}
+

src/Statements.c

@@ -20,28 +20,11 @@
  * 
  */
 
-static char* Types[5]  = { "none", "char", "int", "long", "void" };
+static int TypeSize[9] = { 0,      1,      4,     8,      0,      8,         8,        8,         8}; // in BYTES
-static int TypeSize[5] = { 0,      1,      4,     8,      0}; // in BYTES
-
-int ParseType(int Token) {
-    switch(Token) {
-        case TY_CHAR:
-            return RET_CHAR;
-        
-        case TY_VOID:
-            return RET_VOID;
-        
-        case TY_INT:
-            return RET_INT;
-        
-        default:
-            DieDecimal("Illegal variable type", Token);
-    }
-}
 
 int PrimitiveSize(int Type) {
-    if(Type < RET_NONE || Type > RET_VOID)
+    if(Type < RET_NONE || Type > PTR_VOID)
-        DieMessage("Checking size of bad data type", Types[Type]);
+        DieDecimal("Checking size of bad data type", Type);
     
     return TypeSize[Type];
 }
@@ -145,10 +128,9 @@ int TypesCompatible(int* Left, int* Right, int STRICT) {
  */
 void BeginVariableDeclaration(void) {
     int ID;
-
+    int Type = ParsePointer(CurrentToken.type);
-    int Type = ParseType(CurrentToken.type);
     //printf("type: %s\n", Types[Type]);
-    Tokenise(&CurrentToken);
+    
     VerifyToken(TY_IDENTIFIER, "ident");
     //printf("Identifier: %s\n", CurrentIdentifier);
 
@@ -163,8 +145,8 @@ struct ASTNode* ParseFunction() {
     struct ASTNode* FinalStatement;
     int SymbolSlot, BreakLabel, Type;
 
-    Type = ParseType(CurrentToken.type);
+    Type = ParsePointer(CurrentToken.type);
-    Tokenise(&CurrentToken);
+
     VerifyToken(KW_FUNC, "::");
     VerifyToken(TY_IDENTIFIER, "ident");
 
@@ -251,7 +233,7 @@ struct ASTNode* ParseIdentifier() {
 
     VerifyToken(TY_IDENTIFIER, "ident");
 
-    printf("After parsing, the identifier name is %s, id %d in the symbol table.\n", CurrentIdentifier, FindSymbol(CurrentIdentifier));
+    printf("\t\tAfter parsing, the identifier name is %s, id %d in the symbol table.\n", CurrentIdentifier, FindSymbol(CurrentIdentifier));
 
     if(CurrentToken.type == LI_LPARE)
         return CallFunction();
@@ -386,3 +368,40 @@ struct ASTNode* PrintStatement(void) {
     return Tree;
    
 }
+
+struct ASTNode* PrefixStatement() {
+    struct ASTNode* Tree;
+
+    switch (CurrentToken.type) {
+        case LI_AMP:
+            Tokenise(&CurrentToken);
+
+            // To allow things like:
+            // x = &&y;
+            // We need to recursively parse prefixes;
+            Tree = PrefixStatement();
+
+            if(Tree->Operation != REF_IDENT) 
+                Die("& must be followed by another & or an identifier.");
+
+            Tree->Operation = OP_ADDRESS;
+            Tree->ExprType = PointerTo(Tree->ExprType);
+            break;
+        case AR_STAR:
+            Tokenise(&CurrentToken);
+
+            Tree = PrefixStatement();
+
+            if(Tree->Operation != REF_IDENT && Tree->Operation != OP_DEREF)
+                Die("* must be followed by another * or an identifier.");
+            
+            Tree = ConstructASTBranch(OP_DEREF, ValueAt(Tree->ExprType), Tree, 0);
+            break;
+
+        default:
+            Tree = ParsePrimary();
+
+    }
+
+    return Tree;
+}

tests/pointers

@@ -0,0 +1,22 @@
+int :: main() {
+  char  a;
+  char *b;
+  char  c;
+  int   d;
+  int  *e;
+  int   f;
+
+  a= 18; 
+  PrintInteger(a);
+  b= &a; 
+  c= *b; 
+  PrintInteger(c);
+
+  d= 12; 
+  PrintInteger(d);
+  e= &d; 
+  f= *e; 
+  PrintInteger(f);
+  
+  return(0);
+}