1 /*****************************************************************************/
5 /* Expression evaluation for the ld65 linker */
9 /* (C) 1998-2003 Ullrich von Bassewitz */
10 /* Römerstrasse 52 */
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 /*****************************************************************************/
50 /*****************************************************************************/
52 /*****************************************************************************/
56 static ExprNode* NewExprNode (ObjData* O)
57 /* Create a new expression node */
59 /* Allocate fresh memory */
60 ExprNode* N = xmalloc (sizeof (ExprNode));
72 static void FreeExprNode (ExprNode* E)
81 /*****************************************************************************/
83 /*****************************************************************************/
87 void FreeExpr (ExprNode* Root)
88 /* Free the expression, Root is pointing to. */
91 FreeExpr (Root->Left);
92 FreeExpr (Root->Right);
99 int IsConstExpr (ExprNode* Root)
100 /* Return true if the given expression is a constant expression, that is, one
101 * with no references to external symbols.
107 if (EXPR_IS_LEAF (Root->Op)) {
114 /* Get the referenced export */
115 E = GetExprExport (Root);
116 /* If this export has a mark set, we've already encountered it.
117 * This means that the export is used to define it's own value,
118 * which in turn means, that we have a circular reference.
120 if (ExportHasMark (E)) {
121 CircularRefError (E);
125 Const = IsConstExport (E);
134 } else if (EXPR_IS_UNARY (Root->Op)) {
136 return IsConstExpr (Root->Left);
140 /* We must handle shortcut boolean expressions here */
144 if (IsConstExpr (Root->Left)) {
145 /* lhs is const, if it is zero, don't eval right */
146 if (GetExprVal (Root->Left) == 0) {
149 return IsConstExpr (Root->Right);
152 /* lhs not const --> tree not const */
158 if (IsConstExpr (Root->Left)) {
159 /* lhs is const, if it is not zero, don't eval right */
160 if (GetExprVal (Root->Left) != 0) {
163 return IsConstExpr (Root->Right);
166 /* lhs not const --> tree not const */
172 /* All others are handled normal */
173 return IsConstExpr (Root->Left) && IsConstExpr (Root->Right);
180 Import* GetExprImport (ExprNode* Expr)
181 /* Get the import data structure for a symbol expression node */
183 /* Check that this is really a symbol */
184 PRECONDITION (Expr->Op == EXPR_SYMBOL);
186 /* Return the import */
187 return Expr->Obj->Imports [Expr->V.ImpNum];
192 Export* GetExprExport (ExprNode* Expr)
193 /* Get the exported symbol for a symbol expression node */
195 /* Check that this is really a symbol */
196 PRECONDITION (Expr->Op == EXPR_SYMBOL);
198 /* Return the export */
199 return Expr->Obj->Imports [Expr->V.ImpNum]->Exp;
204 Section* GetExprSection (ExprNode* Expr)
205 /* Get the segment for a section expression node */
207 /* Check that this is really a section node */
208 PRECONDITION (Expr->Op == EXPR_SECTION);
210 /* If we have an object file, get the section from it, otherwise
211 * (internally generated expressions), get the section from the
215 /* Return the export */
216 return Expr->Obj->Sections [Expr->V.SegNum];
224 long GetExprVal (ExprNode* Expr)
225 /* Get the value of a constant expression */
227 long Right, Left, Val;
237 /* Get the referenced export */
238 E = GetExprExport (Expr);
239 /* If this export has a mark set, we've already encountered it.
240 * This means that the export is used to define it's own value,
241 * which in turn means, that we have a circular reference.
243 if (ExportHasMark (E)) {
244 CircularRefError (E);
248 Val = GetExportVal (E);
254 S = GetExprSection (Expr);
255 return S->Offs + S->Seg->PC;
258 return Expr->V.Seg->PC;
261 return Expr->V.Mem->Start;
264 return GetExprVal (Expr->Left) + GetExprVal (Expr->Right);
267 return GetExprVal (Expr->Left) - GetExprVal (Expr->Right);
270 return GetExprVal (Expr->Left) * GetExprVal (Expr->Right);
273 Left = GetExprVal (Expr->Left);
274 Right = GetExprVal (Expr->Right);
276 Error ("Division by zero");
281 Left = GetExprVal (Expr->Left);
282 Right = GetExprVal (Expr->Right);
284 Error ("Modulo operation with zero");
289 return GetExprVal (Expr->Left) | GetExprVal (Expr->Right);
292 return GetExprVal (Expr->Left) ^ GetExprVal (Expr->Right);
295 return GetExprVal (Expr->Left) & GetExprVal (Expr->Right);
298 return GetExprVal (Expr->Left) << GetExprVal (Expr->Right);
301 return GetExprVal (Expr->Left) >> GetExprVal (Expr->Right);
304 return (GetExprVal (Expr->Left) == GetExprVal (Expr->Right));
307 return (GetExprVal (Expr->Left) != GetExprVal (Expr->Right));
310 return (GetExprVal (Expr->Left) < GetExprVal (Expr->Right));
313 return (GetExprVal (Expr->Left) > GetExprVal (Expr->Right));
316 return (GetExprVal (Expr->Left) <= GetExprVal (Expr->Right));
319 return (GetExprVal (Expr->Left) >= GetExprVal (Expr->Right));
321 case EXPR_UNARY_MINUS:
322 return -GetExprVal (Expr->Left);
325 return ~GetExprVal (Expr->Left);
328 return GetExprVal (Expr->Left) & 0xFF;
331 return (GetExprVal (Expr->Left) >> 8) & 0xFF;
334 return (GetExprVal (Expr->Left) >> 16) & 0xFF;
337 return (GetExprVal (Expr->Left) >> 24) & 0xFF;
340 Left = GetExprVal (Expr->Left);
341 return ((Left >> 8) & 0x00FF) | ((Left << 8) & 0xFF00);
344 return GetExprVal (Expr->Left) && GetExprVal (Expr->Right);
347 return GetExprVal (Expr->Left) || GetExprVal (Expr->Right);
350 return (GetExprVal (Expr->Left) != 0) ^ (GetExprVal (Expr->Right) != 0);
353 return !GetExprVal (Expr->Left);
356 Internal ("Unknown expression Op type: %u", Expr->Op);
364 ExprNode* LiteralExpr (long Val, ObjData* O)
365 /* Return an expression tree that encodes the given literal value */
367 ExprNode* Expr = NewExprNode (O);
368 Expr->Op = EXPR_LITERAL;
375 ExprNode* MemoryExpr (Memory* Mem, long Offs, ObjData* O)
376 /* Return an expression tree that encodes an offset into a memory area */
380 ExprNode* Expr = NewExprNode (O);
381 Expr->Op = EXPR_MEMAREA;
385 Root = NewExprNode (O);
386 Root->Op = EXPR_PLUS;
388 Root->Right = LiteralExpr (Offs, O);
398 ExprNode* SegmentExpr (Segment* Seg, long Offs, ObjData* O)
399 /* Return an expression tree that encodes an offset into a segment */
403 ExprNode* Expr = NewExprNode (O);
404 Expr->Op = EXPR_SEGMENT;
408 Root = NewExprNode (O);
409 Root->Op = EXPR_PLUS;
411 Root->Right = LiteralExpr (Offs, O);
421 ExprNode* SectionExpr (Section* Sec, long Offs, ObjData* O)
422 /* Return an expression tree that encodes an offset into a section */
426 ExprNode* Expr = NewExprNode (O);
427 Expr->Op = EXPR_SECTION;
431 Root = NewExprNode (O);
432 Root->Op = EXPR_PLUS;
434 Root->Right = LiteralExpr (Offs, O);
444 ExprNode* ReadExpr (FILE* F, ObjData* O)
445 /* Read an expression from the given file */
449 /* Read the node tag and handle NULL nodes */
450 unsigned char Op = Read8 (F);
451 if (Op == EXPR_NULL) {
455 /* Create a new node */
456 Expr = NewExprNode (O);
459 /* Check the tag and handle the different expression types */
460 if (EXPR_IS_LEAF (Op)) {
464 Expr->V.Val = Read32Signed (F);
468 /* Read the import number */
469 Expr->V.ImpNum = ReadVar (F);
473 /* Read the segment number */
474 Expr->V.SegNum = Read8 (F);
478 Error ("Invalid expression op: %02X", Op);
484 /* Not a leaf node */
485 Expr->Left = ReadExpr (F, O);
486 Expr->Right = ReadExpr (F, O);
490 /* Return the tree */
496 int EqualExpr (ExprNode* E1, ExprNode* E2)
497 /* Check if two expressions are identical. */
499 /* If one pointer is NULL, both must be NULL */
500 if ((E1 == 0) ^ (E2 == 0)) {
507 /* Both pointers not NULL, check OP */
508 if (E1->Op != E2->Op) {
512 /* OPs are identical, check data for leafs, or subtrees */
516 /* Value must be identical */
517 return (E1->V.Val == E2->V.Val);
520 /* Import number must be identical */
521 return (E1->V.ImpNum == E2->V.ImpNum);
524 /* Section must be identical */
525 return (GetExprSection (E1) == GetExprSection (E2));
528 /* Segment must be identical */
529 return (E1->V.Seg == E2->V.Seg);
532 /* Memory area must be identical */
533 return (E1->V.Mem == E2->V.Mem );
536 /* Not a leaf node */
537 return EqualExpr (E1->Left, E2->Left) && EqualExpr (E1->Right, E2->Right);