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 GenLiteralExpr (0);
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 GenLiteralExpr (0);
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 GenLiteralExpr (0);
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");
658 /* Remember the string and skip it */
662 /* Comma must follow */
665 /* Expression expected */
666 Index = ConstExpression ();
668 /* Must be a valid index */
669 if (Index >= (long) strlen (Str)) {
670 Error ("Range error");
671 return GenLiteralExpr (0);
674 /* Get the char, handle as unsigned. Be sure to translate it into
675 * the target character set.
677 C = TgtTranslateChar (Str [(size_t)Index]);
679 /* Return the char expression */
680 return GenLiteralExpr (C);
685 static ExprNode* FuncStrLen (void)
686 /* Handle the .STRLEN function */
690 /* String constant expected */
691 if (Tok != TOK_STRCON) {
693 Error ("String constant expected");
694 /* Smart error recovery */
695 if (Tok != TOK_RPAREN) {
702 /* Get the length of the string */
705 /* Skip the string */
709 /* Return the length */
710 return GenLiteralExpr (Len);
715 static ExprNode* FuncTCount (void)
716 /* Handle the .TCOUNT function */
718 /* We have a list of tokens that ends with the closing paren. Skip
719 * the tokens, and count them. Allow optionally curly braces.
721 enum Token Term = GetTokListTerm (TOK_RPAREN);
723 while (Tok != Term) {
725 /* Check for end of line or end of input. Since the calling function
726 * will check for the closing paren, we don't need to print an error
727 * here, just bail out.
729 if (TokIsSep (Tok)) {
740 /* If the list was enclosed in curly braces, skip the closing brace */
741 if (Term == TOK_RCURLY && Tok == TOK_RCURLY) {
745 /* Return the number of tokens */
746 return GenLiteralExpr (Count);
751 static ExprNode* FuncXMatch (void)
752 /* Handle the .XMATCH function */
754 return DoMatch (tcIdentical);
759 static ExprNode* Function (ExprNode* (*F) (void))
760 /* Handle builtin functions */
764 /* Skip the keyword */
767 /* Expression must be enclosed in braces */
768 if (Tok != TOK_LPAREN) {
769 Error ("'(' expected");
771 return GenLiteralExpr (0);
775 /* Call the function itself */
778 /* Closing brace must follow */
781 /* Return the result of the actual function */
787 static ExprNode* Factor (void)
796 N = GenLiteralExpr (IVal);
801 N = GenLiteralExpr (TgtTranslateChar (IVal));
807 N = Symbol (ParseScopedSymName (SYM_ALLOC_NEW));
810 case TOK_LOCAL_IDENT:
811 N = Symbol (SymFindLocal (SymLast, SVal, SYM_ALLOC_NEW));
828 if (IsEasyConst (L, &Val)) {
830 N = GenLiteralExpr (-Val);
832 N = NewExprNode (EXPR_UNARY_MINUS);
840 if (IsEasyConst (L, &Val)) {
842 N = GenLiteralExpr (~Val);
844 N = NewExprNode (EXPR_NOT);
857 N = LoByte (Factor ());
862 N = HiByte (Factor ());
867 N = BankByte (Factor ());
877 N = Function (FuncBankByte);
881 N = Function (FuncBlank);
885 N = Function (FuncConst);
889 N = GenLiteralExpr (CPUIsets[CPU]);
894 N = Function (FuncDefined);
898 N = Function (FuncHiByte);
902 N = Function (FuncHiWord);
906 N = Function (FuncLoByte);
910 N = Function (FuncLoWord);
914 N = Function (FuncMatch);
918 N = Function (FuncReferenced);
922 N = Function (FuncSizeOf);
926 N = Function (FuncStrAt);
930 N = Function (FuncStrLen);
934 N = Function (FuncTCount);
938 N = GenLiteralExpr (time (0));
943 N = GenLiteralExpr (VERSION);
948 N = Function (FuncXMatch);
952 if (LooseCharTerm && Tok == TOK_STRCON && strlen(SVal) == 1) {
953 /* A character constant */
954 N = GenLiteralExpr (TgtTranslateChar (SVal[0]));
956 N = GenLiteralExpr (0); /* Dummy */
957 Error ("Syntax error");
967 static ExprNode* Term (void)
969 /* Read left hand side */
970 ExprNode* Root = Factor ();
972 /* Handle multiplicative operations */
973 while (Tok == TOK_MUL || Tok == TOK_DIV || Tok == TOK_MOD ||
974 Tok == TOK_AND || Tok == TOK_XOR || Tok == TOK_SHL ||
977 long LVal, RVal, Val;
981 /* Remember the token and skip it */
985 /* Move root to left side and read the right side */
989 /* If both expressions are constant, we can evaluate the term */
990 if (IsEasyConst (Left, &LVal) && IsEasyConst (Right, &RVal)) {
999 Error ("Division by zero");
1008 Error ("Modulo operation with zero");
1024 Val = shl_l (LVal, RVal);
1028 Val = shr_l (LVal, RVal);
1032 Internal ("Invalid token");
1035 /* Generate a literal expression and delete the old left and
1040 Root = GenLiteralExpr (Val);
1044 /* Generate an expression tree */
1047 case TOK_MUL: Op = EXPR_MUL; break;
1048 case TOK_DIV: Op = EXPR_DIV; break;
1049 case TOK_MOD: Op = EXPR_MOD; break;
1050 case TOK_AND: Op = EXPR_AND; break;
1051 case TOK_XOR: Op = EXPR_XOR; break;
1052 case TOK_SHL: Op = EXPR_SHL; break;
1053 case TOK_SHR: Op = EXPR_SHR; break;
1054 default: Internal ("Invalid token");
1056 Root = NewExprNode (Op);
1058 Root->Right = Right;
1064 /* Return the expression tree we've created */
1070 static ExprNode* SimpleExpr (void)
1072 /* Read left hand side */
1073 ExprNode* Root = Term ();
1075 /* Handle additive operations */
1076 while (Tok == TOK_PLUS || Tok == TOK_MINUS || Tok == TOK_OR) {
1078 long LVal, RVal, Val;
1082 /* Remember the token and skip it */
1086 /* Move root to left side and read the right side */
1090 /* If both expressions are constant, we can evaluate the term */
1091 if (IsEasyConst (Left, &LVal) && IsEasyConst (Right, &RVal)) {
1094 case TOK_PLUS: Val = LVal + RVal; break;
1095 case TOK_MINUS: Val = LVal - RVal; break;
1096 case TOK_OR: Val = LVal | RVal; break;
1097 default: Internal ("Invalid token");
1100 /* Generate a literal expression and delete the old left and
1105 Root = GenLiteralExpr (Val);
1109 /* Generate an expression tree */
1112 case TOK_PLUS: Op = EXPR_PLUS; break;
1113 case TOK_MINUS: Op = EXPR_MINUS; break;
1114 case TOK_OR: Op = EXPR_OR; break;
1115 default: Internal ("Invalid token");
1117 Root = NewExprNode (Op);
1119 Root->Right = Right;
1124 /* Return the expression tree we've created */
1130 static ExprNode* BoolExpr (void)
1131 /* Evaluate a boolean expression */
1133 /* Read left hand side */
1134 ExprNode* Root = SimpleExpr ();
1136 /* Handle booleans */
1137 while (Tok == TOK_EQ || Tok == TOK_NE || Tok == TOK_LT ||
1138 Tok == TOK_GT || Tok == TOK_LE || Tok == TOK_GE) {
1140 long LVal, RVal, Val;
1144 /* Remember the token and skip it */
1148 /* Move root to left side and read the right side */
1150 Right = SimpleExpr ();
1152 /* If both expressions are constant, we can evaluate the term */
1153 if (IsEasyConst (Left, &LVal) && IsEasyConst (Right, &RVal)) {
1156 case TOK_EQ: Val = (LVal == RVal); break;
1157 case TOK_NE: Val = (LVal != RVal); break;
1158 case TOK_LT: Val = (LVal < RVal); break;
1159 case TOK_GT: Val = (LVal > RVal); break;
1160 case TOK_LE: Val = (LVal <= RVal); break;
1161 case TOK_GE: Val = (LVal >= RVal); break;
1162 default: Internal ("Invalid token");
1165 /* Generate a literal expression and delete the old left and
1170 Root = GenLiteralExpr (Val);
1174 /* Generate an expression tree */
1177 case TOK_EQ: Op = EXPR_EQ; break;
1178 case TOK_NE: Op = EXPR_NE; break;
1179 case TOK_LT: Op = EXPR_LT; break;
1180 case TOK_GT: Op = EXPR_GT; break;
1181 case TOK_LE: Op = EXPR_LE; break;
1182 case TOK_GE: Op = EXPR_GE; break;
1183 default: Internal ("Invalid token");
1185 Root = NewExprNode (Op);
1187 Root->Right = Right;
1192 /* Return the expression tree we've created */
1198 static ExprNode* Expr2 (void)
1199 /* Boolean operators: AND and XOR */
1201 /* Read left hand side */
1202 ExprNode* Root = BoolExpr ();
1204 /* Handle booleans */
1205 while (Tok == TOK_BOOLAND || Tok == TOK_BOOLXOR) {
1207 long LVal, RVal, Val;
1211 /* Remember the token and skip it */
1215 /* Move root to left side and read the right side */
1217 Right = BoolExpr ();
1219 /* If both expressions are constant, we can evaluate the term */
1220 if (IsEasyConst (Left, &LVal) && IsEasyConst (Right, &RVal)) {
1223 case TOK_BOOLAND: Val = ((LVal != 0) && (RVal != 0)); break;
1224 case TOK_BOOLXOR: Val = ((LVal != 0) ^ (RVal != 0)); break;
1225 default: Internal ("Invalid token");
1228 /* Generate a literal expression and delete the old left and
1233 Root = GenLiteralExpr (Val);
1237 /* Generate an expression tree */
1240 case TOK_BOOLAND: Op = EXPR_BOOLAND; break;
1241 case TOK_BOOLXOR: Op = EXPR_BOOLXOR; break;
1242 default: Internal ("Invalid token");
1244 Root = NewExprNode (Op);
1246 Root->Right = Right;
1251 /* Return the expression tree we've created */
1257 static ExprNode* Expr1 (void)
1258 /* Boolean operators: OR */
1260 /* Read left hand side */
1261 ExprNode* Root = Expr2 ();
1263 /* Handle booleans */
1264 while (Tok == TOK_BOOLOR) {
1266 long LVal, RVal, Val;
1270 /* Remember the token and skip it */
1274 /* Move root to left side and read the right side */
1278 /* If both expressions are constant, we can evaluate the term */
1279 if (IsEasyConst (Left, &LVal) && IsEasyConst (Right, &RVal)) {
1282 case TOK_BOOLOR: Val = ((LVal != 0) || (RVal != 0)); break;
1283 default: Internal ("Invalid token");
1286 /* Generate a literal expression and delete the old left and
1291 Root = GenLiteralExpr (Val);
1295 /* Generate an expression tree */
1298 case TOK_BOOLOR: Op = EXPR_BOOLOR; break;
1299 default: Internal ("Invalid token");
1301 Root = NewExprNode (Op);
1303 Root->Right = Right;
1308 /* Return the expression tree we've created */
1314 static ExprNode* Expr0 (void)
1315 /* Boolean operators: NOT */
1319 /* Handle booleans */
1320 if (Tok == TOK_BOOLNOT) {
1325 /* Skip the operator token */
1328 /* Read the argument */
1331 /* If the argument is const, evaluate it directly */
1332 if (IsEasyConst (Left, &Val)) {
1334 Root = GenLiteralExpr (!Val);
1336 Root = NewExprNode (EXPR_BOOLNOT);
1342 /* Read left hand side */
1347 /* Return the expression tree we've created */
1353 ExprNode* Expression (void)
1354 /* Evaluate an expression, build the expression tree on the heap and return
1355 * a pointer to the root of the tree.
1363 long ConstExpression (void)
1364 /* Parse an expression. Check if the expression is const, and print an error
1365 * message if not. Return the value of the expression, or a dummy, if it is
1371 /* Read the expression */
1372 ExprNode* Expr = Expression ();
1374 /* Study the expression */
1377 StudyExpr (Expr, &D);
1379 /* Check if the expression is constant */
1380 if (ED_IsConst (&D)) {
1383 Error ("Constant expression expected");
1387 /* Free the expression tree and allocated memory for D */
1391 /* Return the value */
1397 void FreeExpr (ExprNode* Root)
1398 /* Free the expression, Root is pointing to. */
1401 FreeExpr (Root->Left);
1402 FreeExpr (Root->Right);
1403 FreeExprNode (Root);
1409 ExprNode* SimplifyExpr (ExprNode* Expr, const ExprDesc* D)
1410 /* Try to simplify the given expression tree */
1412 if (Expr->Op != EXPR_LITERAL && ED_IsConst (D)) {
1413 /* No external references */
1415 Expr = GenLiteralExpr (D->Val);
1422 ExprNode* GenLiteralExpr (long Val)
1423 /* Return an expression tree that encodes the given literal value */
1425 ExprNode* Expr = NewExprNode (EXPR_LITERAL);
1432 ExprNode* GenSymExpr (SymEntry* Sym)
1433 /* Return an expression node that encodes the given symbol */
1435 ExprNode* Expr = NewExprNode (EXPR_SYMBOL);
1437 SymAddExprRef (Sym, Expr);
1443 static ExprNode* GenSectionExpr (unsigned SegNum)
1444 /* Return an expression node for the given section */
1446 ExprNode* Expr = NewExprNode (EXPR_SECTION);
1447 Expr->V.SegNum = SegNum;
1453 ExprNode* GenAddExpr (ExprNode* Left, ExprNode* Right)
1454 /* Generate an addition from the two operands */
1457 if (IsEasyConst (Left, &Val) && Val == 0) {
1460 } else if (IsEasyConst (Right, &Val) && Val == 0) {
1464 ExprNode* Root = NewExprNode (EXPR_PLUS);
1466 Root->Right = Right;
1473 ExprNode* GenCurrentPC (void)
1474 /* Return the current program counter as expression */
1479 /* Create SegmentBase + Offset */
1480 Root = GenAddExpr (GenSectionExpr (GetCurrentSegNum ()),
1481 GenLiteralExpr (GetPC ()));
1483 /* Absolute mode, just return PC value */
1484 Root = GenLiteralExpr (GetPC ());
1492 ExprNode* GenSwapExpr (ExprNode* Expr)
1493 /* Return an extended expression with lo and hi bytes swapped */
1495 ExprNode* N = NewExprNode (EXPR_SWAP);
1502 ExprNode* GenBranchExpr (unsigned Offs)
1503 /* Return an expression that encodes the difference between current PC plus
1504 * offset and the target expression (that is, Expression() - (*+Offs) ).
1511 /* Read Expression() */
1514 /* If the expression is a cheap constant, generate a simpler tree */
1515 if (IsEasyConst (N, &Val)) {
1517 /* Free the constant expression tree */
1520 /* Generate the final expression:
1522 * Val - ((Seg + PC) + Offs)
1523 * Val - Seg - PC - Offs
1524 * (Val - PC - Offs) - Seg
1526 Root = GenLiteralExpr (Val - GetPC () - Offs);
1529 Root = NewExprNode (EXPR_MINUS);
1531 Root->Right = GenSectionExpr (GetCurrentSegNum ());
1536 /* Generate the expression:
1538 * N - ((Seg + PC) + Offs)
1539 * N - Seg - PC - Offs
1540 * N - (PC + Offs) - Seg
1542 Root = NewExprNode (EXPR_MINUS);
1544 Root->Right = GenLiteralExpr (GetPC () + Offs);
1547 Root = NewExprNode (EXPR_MINUS);
1549 Root->Right = GenSectionExpr (GetCurrentSegNum ());
1553 /* Return the result */
1559 ExprNode* GenULabelExpr (unsigned Num)
1560 /* Return an expression for an unnamed label with the given index */
1562 ExprNode* Node = NewExprNode (EXPR_ULABEL);
1565 /* Return the new node */
1571 ExprNode* GenByteExpr (ExprNode* Expr)
1572 /* Force the given expression into a byte and return the result */
1574 /* Use the low byte operator to force the expression into byte size */
1575 return LoByte (Expr);
1580 ExprNode* GenWordExpr (ExprNode* Expr)
1581 /* Force the given expression into a word and return the result. */
1583 /* Use the low byte operator to force the expression into word size */
1584 return LoWord (Expr);
1589 ExprNode* GenNE (ExprNode* Expr, long Val)
1590 /* Generate an expression that compares Expr and Val for inequality */
1592 /* Generate a compare node */
1593 ExprNode* Root = NewExprNode (EXPR_NE);
1595 Root->Right = GenLiteralExpr (Val);
1597 /* Return the result */
1603 int IsConstExpr (ExprNode* Expr, long* Val)
1604 /* Return true if the given expression is a constant expression, that is, one
1605 * with no references to external symbols. If Val is not NULL and the
1606 * expression is constant, the constant value is stored here.
1611 /* Study the expression */
1614 StudyExpr (Expr, &D);
1616 /* Check if the expression is constant */
1617 IsConst = ED_IsConst (&D);
1618 if (IsConst && Val != 0) {
1622 /* Delete allocated memory and return the result */
1629 ExprNode* CloneExpr (ExprNode* Expr)
1630 /* Clone the given expression tree. The function will simply clone symbol
1631 * nodes, it will not resolve them.
1636 /* Accept NULL pointers */
1641 /* Clone the node */
1645 Clone = GenLiteralExpr (Expr->V.Val);
1649 Clone = GenULabelExpr (Expr->V.Val);
1653 Clone = GenSymExpr (Expr->V.Sym);
1657 Clone = GenSectionExpr (Expr->V.SegNum);
1661 /* Generate a new node */
1662 Clone = NewExprNode (Expr->Op);
1663 /* Clone the tree nodes */
1664 Clone->Left = CloneExpr (Expr->Left);
1665 Clone->Right = CloneExpr (Expr->Right);
1675 void WriteExpr (ExprNode* Expr)
1676 /* Write the given expression to the object file */
1678 /* Null expressions are encoded by a type byte of zero */
1680 ObjWrite8 (EXPR_NULL);
1684 /* If the is a leafnode, write the expression attribute, otherwise
1685 * write the expression operands.
1690 ObjWrite8 (EXPR_LITERAL);
1691 ObjWrite32 (Expr->V.Val);
1695 if (SymIsImport (Expr->V.Sym)) {
1696 ObjWrite8 (EXPR_SYMBOL);
1697 ObjWriteVar (GetSymIndex (Expr->V.Sym));
1699 WriteExpr (GetSymExpr (Expr->V.Sym));
1704 ObjWrite8 (EXPR_SECTION);
1705 ObjWrite8 (Expr->V.SegNum);
1709 WriteExpr (ULabResolve (Expr->V.Val));
1713 /* Not a leaf node */
1714 ObjWrite8 (Expr->Op);
1715 WriteExpr (Expr->Left);
1716 WriteExpr (Expr->Right);