1 /*****************************************************************************/
5 /* Expression evaluation for the ca65 macroassembler */
9 /* (C) 1998-2004 Ullrich von Bassewitz */
11 /* D-70794 Filderstadt */
12 /* EMail: uz@cc65.org */
15 /* This software is provided 'as-is', without any expressed or implied */
16 /* warranty. In no event will the authors be held liable for any damages */
17 /* arising from the use of this software. */
19 /* Permission is granted to anyone to use this software for any purpose, */
20 /* including commercial applications, and to alter it and redistribute it */
21 /* freely, subject to the following restrictions: */
23 /* 1. The origin of this software must not be misrepresented; you must not */
24 /* claim that you wrote the original software. If you use this software */
25 /* in a product, an acknowledgment in the product documentation would be */
26 /* appreciated but is not required. */
27 /* 2. Altered source versions must be plainly marked as such, and must not */
28 /* be misrepresented as being the original software. */
29 /* 3. This notice may not be removed or altered from any source */
32 /*****************************************************************************/
59 #include "studyexpr.h"
67 /*****************************************************************************/
69 /*****************************************************************************/
73 /* Since all expressions are first packed into expression trees, and each
74 * expression tree node is allocated on the heap, we add some type of special
75 * purpose memory allocation here: Instead of freeing the nodes, we save some
76 * number of freed nodes for later and remember them in a single linked list
77 * using the Left link.
79 #define MAX_FREE_NODES 64
80 static ExprNode* FreeExprNodes = 0;
81 static unsigned FreeNodeCount = 0;
85 /*****************************************************************************/
87 /*****************************************************************************/
91 static ExprNode* NewExprNode (unsigned Op)
92 /* Create a new expression node */
96 /* Do we have some nodes in the list already? */
98 /* Use first node from list */
100 FreeExprNodes = N->Left;
102 /* Allocate fresh memory */
103 N = xmalloc (sizeof (ExprNode));
106 N->Left = N->Right = 0;
114 static void FreeExprNode (ExprNode* E)
118 if (E->Op == EXPR_SYMBOL) {
119 /* Remove the symbol reference */
120 SymDelExprRef (E->V.Sym, E);
122 /* Place the symbol into the free nodes list if possible */
123 if (FreeNodeCount < MAX_FREE_NODES) {
124 /* Remember this node for later */
125 E->Left = FreeExprNodes;
128 /* Free the memory */
136 /*****************************************************************************/
138 /*****************************************************************************/
142 static ExprNode* Expr0 (void);
146 int IsByteRange (long Val)
147 /* Return true if this is a byte value */
149 return (Val & ~0xFFL) == 0;
154 int IsWordRange (long Val)
155 /* Return true if this is a word value */
157 return (Val & ~0xFFFFL) == 0;
162 int IsFarRange (long Val)
163 /* Return true if this is a far (24 bit) value */
165 return (Val & ~0xFFFFFFL) == 0;
170 static int IsEasyConst (const ExprNode* E, long* Val)
171 /* Do some light checking if the given node is a constant. Don't care if E is
172 * a complex expression. If E is a constant, return true and place its value
173 * into Val, provided that Val is not NULL.
176 /* Resolve symbols, follow symbol chains */
177 while (E->Op == EXPR_SYMBOL) {
178 E = SymResolve (E->V.Sym);
180 /* Could not resolve */
185 /* Symbols resolved, check for a literal */
186 if (E->Op == EXPR_LITERAL) {
193 /* Not found to be a const according to our tests */
199 static ExprNode* LoByte (ExprNode* Operand)
200 /* Return the low byte of the given expression */
205 /* Special handling for const expressions */
206 if (IsEasyConst (Operand, &Val)) {
208 Expr = GenLiteralExpr (Val & 0xFF);
210 /* Extract byte #0 */
211 Expr = NewExprNode (EXPR_BYTE0);
212 Expr->Left = Operand;
219 static ExprNode* HiByte (ExprNode* Operand)
220 /* Return the high byte of the given expression */
225 /* Special handling for const expressions */
226 if (IsEasyConst (Operand, &Val)) {
228 Expr = GenLiteralExpr ((Val >> 8) & 0xFF);
230 /* Extract byte #1 */
231 Expr = NewExprNode (EXPR_BYTE1);
232 Expr->Left = Operand;
239 static ExprNode* BankByte (ExprNode* Operand)
240 /* Return the bank byte of the given expression */
245 /* Special handling for const expressions */
246 if (IsEasyConst (Operand, &Val)) {
248 Expr = GenLiteralExpr ((Val >> 16) & 0xFF);
250 /* Extract byte #2 */
251 Expr = NewExprNode (EXPR_BYTE2);
252 Expr->Left = Operand;
259 static ExprNode* LoWord (ExprNode* Operand)
260 /* Return the low word of the given expression */
265 /* Special handling for const expressions */
266 if (IsEasyConst (Operand, &Val)) {
268 Expr = GenLiteralExpr (Val & 0xFFFF);
270 /* Extract word #0 */
271 Expr = NewExprNode (EXPR_WORD0);
272 Expr->Left = Operand;
279 static ExprNode* HiWord (ExprNode* Operand)
280 /* Return the high word of the given expression */
285 /* Special handling for const expressions */
286 if (IsEasyConst (Operand, &Val)) {
288 Expr = GenLiteralExpr ((Val >> 16) & 0xFFFF);
290 /* Extract word #1 */
291 Expr = NewExprNode (EXPR_WORD1);
292 Expr->Left = Operand;
299 static ExprNode* Symbol (SymEntry* S)
300 /* Reference a symbol and return an expression for it */
303 /* Some weird error happened before */
304 return GenLiteralExpr (0);
306 /* Mark the symbol as referenced */
308 /* If the symbol is a variable, return just its value, otherwise
309 * return a reference to the symbol.
312 return CloneExpr (GetSymExpr (S));
314 /* Create symbol node */
315 return GenSymExpr (S);
322 static ExprNode* FuncBankByte (void)
323 /* Handle the .BANKBYTE builtin function */
325 return BankByte (Expression ());
330 static ExprNode* FuncBlank (void)
331 /* Handle the .BLANK builtin function */
333 /* We have a list of tokens that ends with the closing paren. Skip
334 * the tokens, and count them. Allow optionally curly braces.
336 enum Token Term = GetTokListTerm (TOK_RPAREN);
338 while (Tok != Term) {
340 /* Check for end of line or end of input. Since the calling function
341 * will check for the closing paren, we don't need to print an error
342 * here, just bail out.
344 if (TokIsSep (Tok)) {
355 /* If the list was enclosed in curly braces, skip the closing brace */
356 if (Term == TOK_RCURLY && Tok == TOK_RCURLY) {
360 /* Return true if the list was empty */
361 return GenLiteralExpr (Count == 0);
366 static ExprNode* FuncConst (void)
367 /* Handle the .CONST builtin function */
369 /* Read an expression */
370 ExprNode* Expr = Expression ();
372 /* Check the constness of the expression */
373 ExprNode* Result = GenLiteralExpr (IsConstExpr (Expr, 0));
375 /* Free the expression */
384 static ExprNode* FuncDefined (void)
385 /* Handle the .DEFINED builtin function */
387 /* Parse the symbol name and search for the symbol */
388 SymEntry* Sym = ParseScopedSymName (SYM_FIND_EXISTING);
390 /* Check if the symbol is defined */
391 return GenLiteralExpr (Sym != 0 && SymIsDef (Sym));
396 static ExprNode* FuncHiByte (void)
397 /* Handle the .HIBYTE builtin function */
399 return HiByte (Expression ());
404 static ExprNode* FuncHiWord (void)
405 /* Handle the .HIWORD builtin function */
407 return HiWord (Expression ());
412 static ExprNode* FuncLoByte (void)
413 /* Handle the .LOBYTE builtin function */
415 return LoByte (Expression ());
420 static ExprNode* FuncLoWord (void)
421 /* Handle the .LOWORD builtin function */
423 return LoWord (Expression ());
428 static ExprNode* DoMatch (enum TC EqualityLevel)
429 /* Handle the .MATCH and .XMATCH builtin functions */
436 /* A list of tokens follows. Read this list and remember it building a
437 * single linked list of tokens including attributes. The list is
438 * either enclosed in curly braces, or terminated by a comma.
440 enum Token Term = GetTokListTerm (TOK_COMMA);
441 while (Tok != Term) {
443 /* We may not end-of-line of end-of-file here */
444 if (TokIsSep (Tok)) {
445 Error ("Unexpected end of line");
446 return GenLiteral0 ();
449 /* Get a node with this token */
450 Node = NewTokNode ();
452 /* Insert the node into the list */
464 /* Skip the terminator token*/
467 /* If the token list was enclosed in curly braces, we expect a comma */
468 if (Term == TOK_RCURLY) {
472 /* Read the second list which is optionally enclosed in curly braces and
473 * terminated by the right parenthesis. Compare each token against the
474 * one in the first list.
476 Term = GetTokListTerm (TOK_RPAREN);
479 while (Tok != Term) {
481 /* We may not end-of-line of end-of-file here */
482 if (TokIsSep (Tok)) {
483 Error ("Unexpected end of line");
484 return GenLiteral0 ();
487 /* Compare the tokens if the result is not already known */
490 /* The second list is larger than the first one */
492 } else if (TokCmp (Node) < EqualityLevel) {
493 /* Tokens do not match */
498 /* Next token in first list */
503 /* Next token in current list */
507 /* If the token list was enclosed in curly braces, eat the closing brace */
508 if (Term == TOK_RCURLY) {
512 /* Check if there are remaining tokens in the first list */
517 /* Free the token list */
524 /* Done, return the result */
525 return GenLiteralExpr (Result);
530 static ExprNode* FuncMatch (void)
531 /* Handle the .MATCH function */
533 return DoMatch (tcSameToken);
538 static ExprNode* FuncReferenced (void)
539 /* Handle the .REFERENCED builtin function */
541 /* Parse the symbol name and search for the symbol */
542 SymEntry* Sym = ParseScopedSymName (SYM_FIND_EXISTING);
544 /* Check if the symbol is referenced */
545 return GenLiteralExpr (Sym != 0 && SymIsRef (Sym));
550 static ExprNode* FuncSizeOf (void)
551 /* Handle the .SIZEOF function */
553 StrBuf ScopeName = AUTO_STRBUF_INITIALIZER;
554 char Name[sizeof (SVal)];
562 /* Assume an error */
565 /* Check for a cheap local which needs special handling */
566 if (Tok == TOK_LOCAL_IDENT) {
568 /* Cheap local symbol */
569 Sym = SymFindLocal (SymLast, SVal, SYM_FIND_EXISTING);
571 Error ("Unknown symbol or scope: `%s'", SVal);
573 SizeSym = GetSizeOfSymbol (Sym);
576 /* Remember and skip SVal, terminate ScopeName so it is empty */
579 SB_Terminate (&ScopeName);
583 /* Parse the scope and the name */
584 SymTable* ParentScope = ParseScopedIdent (Name, &ScopeName);
586 /* Check if the parent scope is valid */
587 if (ParentScope == 0) {
589 DoneStrBuf (&ScopeName);
590 return GenLiteral0 ();
593 /* If ScopeName is empty, no explicit scope was specified. We have to
594 * search upper scope levels in this case.
596 NoScope = SB_IsEmpty (&ScopeName);
598 /* First search for a scope with the given name */
600 Scope = SymFindAnyScope (ParentScope, Name);
602 Scope = SymFindScope (ParentScope, Name, SYM_FIND_EXISTING);
605 /* If we did find a scope with the name, read the symbol defining the
606 * size, otherwise search for a symbol entry with the name and scope.
609 /* Yep, it's a scope */
610 SizeSym = GetSizeOfScope (Scope);
613 Sym = SymFindAny (ParentScope, Name);
615 Sym = SymFind (ParentScope, Name, SYM_FIND_EXISTING);
618 /* If we found the symbol retrieve the size, otherwise complain */
620 SizeSym = GetSizeOfSymbol (Sym);
622 Error ("Unknown symbol or scope: `%s%s'",
623 SB_GetConstBuf (&ScopeName), Name);
628 /* Check if we have a size */
629 if (SizeSym == 0 || !SymIsConst (SizeSym, &Size)) {
630 Error ("Size of `%s%s' is unknown", SB_GetConstBuf (&ScopeName), Name);
634 /* Free the scope name */
635 DoneStrBuf (&ScopeName);
637 /* Return the size */
638 return GenLiteralExpr (Size);
643 static ExprNode* FuncStrAt (void)
644 /* Handle the .STRAT function */
646 char Str [sizeof(SVal)];
650 /* String constant expected */
651 if (Tok != TOK_STRCON) {
652 Error ("String constant expected");
654 return GenLiteral0 ();
657 /* Remember the string and skip it */
661 /* Comma must follow */
664 /* Expression expected */
665 Index = ConstExpression ();
667 /* Must be a valid index */
668 if (Index >= (long) strlen (Str)) {
669 Error ("Range error");
670 return GenLiteral0 ();
673 /* Get the char, handle as unsigned. Be sure to translate it into
674 * the target character set.
676 C = TgtTranslateChar (Str [(size_t)Index]);
678 /* Return the char expression */
679 return GenLiteralExpr (C);
684 static ExprNode* FuncStrLen (void)
685 /* Handle the .STRLEN function */
689 /* String constant expected */
690 if (Tok != TOK_STRCON) {
692 Error ("String constant expected");
693 /* Smart error recovery */
694 if (Tok != TOK_RPAREN) {
701 /* Get the length of the string */
704 /* Skip the string */
708 /* Return the length */
709 return GenLiteralExpr (Len);
714 static ExprNode* FuncTCount (void)
715 /* Handle the .TCOUNT function */
717 /* We have a list of tokens that ends with the closing paren. Skip
718 * the tokens, and count them. Allow optionally curly braces.
720 enum Token Term = GetTokListTerm (TOK_RPAREN);
722 while (Tok != Term) {
724 /* Check for end of line or end of input. Since the calling function
725 * will check for the closing paren, we don't need to print an error
726 * here, just bail out.
728 if (TokIsSep (Tok)) {
739 /* If the list was enclosed in curly braces, skip the closing brace */
740 if (Term == TOK_RCURLY && Tok == TOK_RCURLY) {
744 /* Return the number of tokens */
745 return GenLiteralExpr (Count);
750 static ExprNode* FuncXMatch (void)
751 /* Handle the .XMATCH function */
753 return DoMatch (tcIdentical);
758 static ExprNode* Function (ExprNode* (*F) (void))
759 /* Handle builtin functions */
763 /* Skip the keyword */
766 /* Expression must be enclosed in braces */
767 if (Tok != TOK_LPAREN) {
768 Error ("'(' expected");
770 return GenLiteral0 ();
774 /* Call the function itself */
777 /* Closing brace must follow */
780 /* Return the result of the actual function */
786 static ExprNode* Factor (void)
795 N = GenLiteralExpr (IVal);
800 N = GenLiteralExpr (TgtTranslateChar (IVal));
806 N = Symbol (ParseScopedSymName (SYM_ALLOC_NEW));
809 case TOK_LOCAL_IDENT:
810 N = Symbol (SymFindLocal (SymLast, SVal, SYM_ALLOC_NEW));
827 if (IsEasyConst (L, &Val)) {
829 N = GenLiteralExpr (-Val);
831 N = NewExprNode (EXPR_UNARY_MINUS);
839 if (IsEasyConst (L, &Val)) {
841 N = GenLiteralExpr (~Val);
843 N = NewExprNode (EXPR_NOT);
856 N = LoByte (Factor ());
861 N = HiByte (Factor ());
866 N = BankByte (Factor ());
876 N = Function (FuncBankByte);
880 N = Function (FuncBlank);
884 N = Function (FuncConst);
888 N = GenLiteralExpr (CPUIsets[CPU]);
893 N = Function (FuncDefined);
897 N = Function (FuncHiByte);
901 N = Function (FuncHiWord);
905 N = Function (FuncLoByte);
909 N = Function (FuncLoWord);
913 N = Function (FuncMatch);
917 N = Function (FuncReferenced);
921 N = Function (FuncSizeOf);
925 N = Function (FuncStrAt);
929 N = Function (FuncStrLen);
933 N = Function (FuncTCount);
937 N = GenLiteralExpr (time (0));
942 N = GenLiteralExpr (VERSION);
947 N = Function (FuncXMatch);
951 if (LooseCharTerm && Tok == TOK_STRCON && strlen(SVal) == 1) {
952 /* A character constant */
953 N = GenLiteralExpr (TgtTranslateChar (SVal[0]));
955 N = GenLiteral0 (); /* Dummy */
956 Error ("Syntax error");
966 static ExprNode* Term (void)
968 /* Read left hand side */
969 ExprNode* Root = Factor ();
971 /* Handle multiplicative operations */
972 while (Tok == TOK_MUL || Tok == TOK_DIV || Tok == TOK_MOD ||
973 Tok == TOK_AND || Tok == TOK_XOR || Tok == TOK_SHL ||
976 long LVal, RVal, Val;
980 /* Remember the token and skip it */
984 /* Move root to left side and read the right side */
988 /* If both expressions are constant, we can evaluate the term */
989 if (IsEasyConst (Left, &LVal) && IsEasyConst (Right, &RVal)) {
998 Error ("Division by zero");
1007 Error ("Modulo operation with zero");
1023 Val = shl_l (LVal, RVal);
1027 Val = shr_l (LVal, RVal);
1031 Internal ("Invalid token");
1034 /* Generate a literal expression and delete the old left and
1039 Root = GenLiteralExpr (Val);
1043 /* Generate an expression tree */
1046 case TOK_MUL: Op = EXPR_MUL; break;
1047 case TOK_DIV: Op = EXPR_DIV; break;
1048 case TOK_MOD: Op = EXPR_MOD; break;
1049 case TOK_AND: Op = EXPR_AND; break;
1050 case TOK_XOR: Op = EXPR_XOR; break;
1051 case TOK_SHL: Op = EXPR_SHL; break;
1052 case TOK_SHR: Op = EXPR_SHR; break;
1053 default: Internal ("Invalid token");
1055 Root = NewExprNode (Op);
1057 Root->Right = Right;
1063 /* Return the expression tree we've created */
1069 static ExprNode* SimpleExpr (void)
1071 /* Read left hand side */
1072 ExprNode* Root = Term ();
1074 /* Handle additive operations */
1075 while (Tok == TOK_PLUS || Tok == TOK_MINUS || Tok == TOK_OR) {
1077 long LVal, RVal, Val;
1081 /* Remember the token and skip it */
1085 /* Move root to left side and read the right side */
1089 /* If both expressions are constant, we can evaluate the term */
1090 if (IsEasyConst (Left, &LVal) && IsEasyConst (Right, &RVal)) {
1093 case TOK_PLUS: Val = LVal + RVal; break;
1094 case TOK_MINUS: Val = LVal - RVal; break;
1095 case TOK_OR: Val = LVal | RVal; break;
1096 default: Internal ("Invalid token");
1099 /* Generate a literal expression and delete the old left and
1104 Root = GenLiteralExpr (Val);
1108 /* Generate an expression tree */
1111 case TOK_PLUS: Op = EXPR_PLUS; break;
1112 case TOK_MINUS: Op = EXPR_MINUS; break;
1113 case TOK_OR: Op = EXPR_OR; break;
1114 default: Internal ("Invalid token");
1116 Root = NewExprNode (Op);
1118 Root->Right = Right;
1123 /* Return the expression tree we've created */
1129 static ExprNode* BoolExpr (void)
1130 /* Evaluate a boolean expression */
1132 /* Read left hand side */
1133 ExprNode* Root = SimpleExpr ();
1135 /* Handle booleans */
1136 while (Tok == TOK_EQ || Tok == TOK_NE || Tok == TOK_LT ||
1137 Tok == TOK_GT || Tok == TOK_LE || Tok == TOK_GE) {
1139 long LVal, RVal, Val;
1143 /* Remember the token and skip it */
1147 /* Move root to left side and read the right side */
1149 Right = SimpleExpr ();
1151 /* If both expressions are constant, we can evaluate the term */
1152 if (IsEasyConst (Left, &LVal) && IsEasyConst (Right, &RVal)) {
1155 case TOK_EQ: Val = (LVal == RVal); break;
1156 case TOK_NE: Val = (LVal != RVal); break;
1157 case TOK_LT: Val = (LVal < RVal); break;
1158 case TOK_GT: Val = (LVal > RVal); break;
1159 case TOK_LE: Val = (LVal <= RVal); break;
1160 case TOK_GE: Val = (LVal >= RVal); break;
1161 default: Internal ("Invalid token");
1164 /* Generate a literal expression and delete the old left and
1169 Root = GenLiteralExpr (Val);
1173 /* Generate an expression tree */
1176 case TOK_EQ: Op = EXPR_EQ; break;
1177 case TOK_NE: Op = EXPR_NE; break;
1178 case TOK_LT: Op = EXPR_LT; break;
1179 case TOK_GT: Op = EXPR_GT; break;
1180 case TOK_LE: Op = EXPR_LE; break;
1181 case TOK_GE: Op = EXPR_GE; break;
1182 default: Internal ("Invalid token");
1184 Root = NewExprNode (Op);
1186 Root->Right = Right;
1191 /* Return the expression tree we've created */
1197 static ExprNode* Expr2 (void)
1198 /* Boolean operators: AND and XOR */
1200 /* Read left hand side */
1201 ExprNode* Root = BoolExpr ();
1203 /* Handle booleans */
1204 while (Tok == TOK_BOOLAND || Tok == TOK_BOOLXOR) {
1206 long LVal, RVal, Val;
1210 /* Remember the token and skip it */
1214 /* Move root to left side and read the right side */
1216 Right = BoolExpr ();
1218 /* If both expressions are constant, we can evaluate the term */
1219 if (IsEasyConst (Left, &LVal) && IsEasyConst (Right, &RVal)) {
1222 case TOK_BOOLAND: Val = ((LVal != 0) && (RVal != 0)); break;
1223 case TOK_BOOLXOR: Val = ((LVal != 0) ^ (RVal != 0)); break;
1224 default: Internal ("Invalid token");
1227 /* Generate a literal expression and delete the old left and
1232 Root = GenLiteralExpr (Val);
1236 /* Generate an expression tree */
1239 case TOK_BOOLAND: Op = EXPR_BOOLAND; break;
1240 case TOK_BOOLXOR: Op = EXPR_BOOLXOR; break;
1241 default: Internal ("Invalid token");
1243 Root = NewExprNode (Op);
1245 Root->Right = Right;
1250 /* Return the expression tree we've created */
1256 static ExprNode* Expr1 (void)
1257 /* Boolean operators: OR */
1259 /* Read left hand side */
1260 ExprNode* Root = Expr2 ();
1262 /* Handle booleans */
1263 while (Tok == TOK_BOOLOR) {
1265 long LVal, RVal, Val;
1269 /* Remember the token and skip it */
1273 /* Move root to left side and read the right side */
1277 /* If both expressions are constant, we can evaluate the term */
1278 if (IsEasyConst (Left, &LVal) && IsEasyConst (Right, &RVal)) {
1281 case TOK_BOOLOR: Val = ((LVal != 0) || (RVal != 0)); break;
1282 default: Internal ("Invalid token");
1285 /* Generate a literal expression and delete the old left and
1290 Root = GenLiteralExpr (Val);
1294 /* Generate an expression tree */
1297 case TOK_BOOLOR: Op = EXPR_BOOLOR; break;
1298 default: Internal ("Invalid token");
1300 Root = NewExprNode (Op);
1302 Root->Right = Right;
1307 /* Return the expression tree we've created */
1313 static ExprNode* Expr0 (void)
1314 /* Boolean operators: NOT */
1318 /* Handle booleans */
1319 if (Tok == TOK_BOOLNOT) {
1324 /* Skip the operator token */
1327 /* Read the argument */
1330 /* If the argument is const, evaluate it directly */
1331 if (IsEasyConst (Left, &Val)) {
1333 Root = GenLiteralExpr (!Val);
1335 Root = NewExprNode (EXPR_BOOLNOT);
1341 /* Read left hand side */
1346 /* Return the expression tree we've created */
1352 ExprNode* Expression (void)
1353 /* Evaluate an expression, build the expression tree on the heap and return
1354 * a pointer to the root of the tree.
1362 long ConstExpression (void)
1363 /* Parse an expression. Check if the expression is const, and print an error
1364 * message if not. Return the value of the expression, or a dummy, if it is
1370 /* Read the expression */
1371 ExprNode* Expr = Expression ();
1373 /* Study the expression */
1376 StudyExpr (Expr, &D);
1378 /* Check if the expression is constant */
1379 if (ED_IsConst (&D)) {
1382 Error ("Constant expression expected");
1386 /* Free the expression tree and allocated memory for D */
1390 /* Return the value */
1396 void FreeExpr (ExprNode* Root)
1397 /* Free the expression, Root is pointing to. */
1400 FreeExpr (Root->Left);
1401 FreeExpr (Root->Right);
1402 FreeExprNode (Root);
1408 ExprNode* SimplifyExpr (ExprNode* Expr, const ExprDesc* D)
1409 /* Try to simplify the given expression tree */
1411 if (Expr->Op != EXPR_LITERAL && ED_IsConst (D)) {
1412 /* No external references */
1414 Expr = GenLiteralExpr (D->Val);
1421 ExprNode* GenLiteralExpr (long Val)
1422 /* Return an expression tree that encodes the given literal value */
1424 ExprNode* Expr = NewExprNode (EXPR_LITERAL);
1431 ExprNode* GenLiteral0 (void)
1432 /* Return an expression tree that encodes the the number zero */
1434 return GenLiteralExpr (0);
1439 ExprNode* GenSymExpr (SymEntry* Sym)
1440 /* Return an expression node that encodes the given symbol */
1442 ExprNode* Expr = NewExprNode (EXPR_SYMBOL);
1444 SymAddExprRef (Sym, Expr);
1450 static ExprNode* GenSectionExpr (unsigned SegNum)
1451 /* Return an expression node for the given section */
1453 ExprNode* Expr = NewExprNode (EXPR_SECTION);
1454 Expr->V.SegNum = SegNum;
1460 ExprNode* GenAddExpr (ExprNode* Left, ExprNode* Right)
1461 /* Generate an addition from the two operands */
1464 if (IsEasyConst (Left, &Val) && Val == 0) {
1467 } else if (IsEasyConst (Right, &Val) && Val == 0) {
1471 ExprNode* Root = NewExprNode (EXPR_PLUS);
1473 Root->Right = Right;
1480 ExprNode* GenCurrentPC (void)
1481 /* Return the current program counter as expression */
1486 /* Create SegmentBase + Offset */
1487 Root = GenAddExpr (GenSectionExpr (GetCurrentSegNum ()),
1488 GenLiteralExpr (GetPC ()));
1490 /* Absolute mode, just return PC value */
1491 Root = GenLiteralExpr (GetPC ());
1499 ExprNode* GenSwapExpr (ExprNode* Expr)
1500 /* Return an extended expression with lo and hi bytes swapped */
1502 ExprNode* N = NewExprNode (EXPR_SWAP);
1509 ExprNode* GenBranchExpr (unsigned Offs)
1510 /* Return an expression that encodes the difference between current PC plus
1511 * offset and the target expression (that is, Expression() - (*+Offs) ).
1518 /* Read Expression() */
1521 /* If the expression is a cheap constant, generate a simpler tree */
1522 if (IsEasyConst (N, &Val)) {
1524 /* Free the constant expression tree */
1527 /* Generate the final expression:
1529 * Val - ((Seg + PC) + Offs)
1530 * Val - Seg - PC - Offs
1531 * (Val - PC - Offs) - Seg
1533 Root = GenLiteralExpr (Val - GetPC () - Offs);
1536 Root = NewExprNode (EXPR_MINUS);
1538 Root->Right = GenSectionExpr (GetCurrentSegNum ());
1543 /* Generate the expression:
1545 * N - ((Seg + PC) + Offs)
1546 * N - Seg - PC - Offs
1547 * N - (PC + Offs) - Seg
1549 Root = NewExprNode (EXPR_MINUS);
1551 Root->Right = GenLiteralExpr (GetPC () + Offs);
1554 Root = NewExprNode (EXPR_MINUS);
1556 Root->Right = GenSectionExpr (GetCurrentSegNum ());
1560 /* Return the result */
1566 ExprNode* GenULabelExpr (unsigned Num)
1567 /* Return an expression for an unnamed label with the given index */
1569 ExprNode* Node = NewExprNode (EXPR_ULABEL);
1572 /* Return the new node */
1578 ExprNode* GenByteExpr (ExprNode* Expr)
1579 /* Force the given expression into a byte and return the result */
1581 /* Use the low byte operator to force the expression into byte size */
1582 return LoByte (Expr);
1587 ExprNode* GenWordExpr (ExprNode* Expr)
1588 /* Force the given expression into a word and return the result. */
1590 /* Use the low byte operator to force the expression into word size */
1591 return LoWord (Expr);
1596 ExprNode* GenNE (ExprNode* Expr, long Val)
1597 /* Generate an expression that compares Expr and Val for inequality */
1599 /* Generate a compare node */
1600 ExprNode* Root = NewExprNode (EXPR_NE);
1602 Root->Right = GenLiteralExpr (Val);
1604 /* Return the result */
1610 int IsConstExpr (ExprNode* Expr, long* Val)
1611 /* Return true if the given expression is a constant expression, that is, one
1612 * with no references to external symbols. If Val is not NULL and the
1613 * expression is constant, the constant value is stored here.
1618 /* Study the expression */
1621 StudyExpr (Expr, &D);
1623 /* Check if the expression is constant */
1624 IsConst = ED_IsConst (&D);
1625 if (IsConst && Val != 0) {
1629 /* Delete allocated memory and return the result */
1636 ExprNode* CloneExpr (ExprNode* Expr)
1637 /* Clone the given expression tree. The function will simply clone symbol
1638 * nodes, it will not resolve them.
1643 /* Accept NULL pointers */
1648 /* Clone the node */
1652 Clone = GenLiteralExpr (Expr->V.Val);
1656 Clone = GenULabelExpr (Expr->V.Val);
1660 Clone = GenSymExpr (Expr->V.Sym);
1664 Clone = GenSectionExpr (Expr->V.SegNum);
1668 /* Generate a new node */
1669 Clone = NewExprNode (Expr->Op);
1670 /* Clone the tree nodes */
1671 Clone->Left = CloneExpr (Expr->Left);
1672 Clone->Right = CloneExpr (Expr->Right);
1682 void WriteExpr (ExprNode* Expr)
1683 /* Write the given expression to the object file */
1685 /* Null expressions are encoded by a type byte of zero */
1687 ObjWrite8 (EXPR_NULL);
1691 /* If the is a leafnode, write the expression attribute, otherwise
1692 * write the expression operands.
1697 ObjWrite8 (EXPR_LITERAL);
1698 ObjWrite32 (Expr->V.Val);
1702 if (SymIsImport (Expr->V.Sym)) {
1703 ObjWrite8 (EXPR_SYMBOL);
1704 ObjWriteVar (GetSymIndex (Expr->V.Sym));
1706 WriteExpr (GetSymExpr (Expr->V.Sym));
1711 ObjWrite8 (EXPR_SECTION);
1712 ObjWrite8 (Expr->V.SegNum);
1716 WriteExpr (ULabResolve (Expr->V.Val));
1720 /* Not a leaf node */
1721 ObjWrite8 (Expr->Op);
1722 WriteExpr (Expr->Left);
1723 WriteExpr (Expr->Right);