1 | /*****************************************************************************/ |
2 | /* */ |
3 | /* ulabel.c */ |
4 | /* */ |
5 | /* Unnamed labels for the ca65 macroassembler */ |
6 | /* */ |
7 | /* */ |
8 | /* */ |
9 | /* (C) 2000-2011, Ullrich von Bassewitz */ |
10 | /* Roemerstrasse 52 */ |
11 | /* D-70794 Filderstadt */ |
12 | /* EMail: uz@cc65.org */ |
13 | /* */ |
14 | /* */ |
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. */ |
18 | /* */ |
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: */ |
22 | /* */ |
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 */ |
30 | /* distribution. */ |
31 | /* */ |
32 | /*****************************************************************************/ |
33 | |
34 | |
35 | |
36 | /* common */ |
37 | #include "check.h" |
38 | #include "coll.h" |
39 | #include "xmalloc.h" |
40 | |
41 | /* ca65 */ |
42 | #include "error.h" |
43 | #include "expr.h" |
44 | #include "lineinfo.h" |
45 | #include "scanner.h" |
46 | #include "ulabel.h" |
47 | |
48 | |
49 | |
50 | /*****************************************************************************/ |
51 | /* Data */ |
52 | /*****************************************************************************/ |
53 | |
54 | |
55 | |
56 | /* Struct that describes an unnamed label */ |
57 | typedef struct ULabel ULabel; |
58 | struct ULabel { |
59 | Collection LineInfos; /* Position of the label in the source */ |
60 | ExprNode* Val; /* The label value - may be NULL */ |
61 | unsigned Ref; /* Number of references */ |
62 | }; |
63 | |
64 | /* List management */ |
65 | static Collection ULabList = STATIC_COLLECTION_INITIALIZER; |
66 | static unsigned ULabDefCount = 0; /* Number of defined labels */ |
67 | |
68 | |
69 | |
70 | /*****************************************************************************/ |
71 | /* Code */ |
72 | /*****************************************************************************/ |
73 | |
74 | |
75 | |
76 | static ULabel* NewULabel (ExprNode* Val) |
77 | /* Create a new ULabel and insert it into the collection. The created label |
78 | ** structure is returned. |
79 | */ |
80 | { |
81 | /* Allocate memory for the ULabel structure */ |
82 | ULabel* L = xmalloc (sizeof (ULabel)); |
83 | |
84 | /* Initialize the fields */ |
85 | L->LineInfos = EmptyCollection; |
86 | GetFullLineInfo (&L->LineInfos); |
87 | L->Val = Val; |
88 | L->Ref = 0; |
89 | |
90 | /* Insert the label into the collection */ |
91 | CollAppend (&ULabList, L); |
92 | |
93 | /* Return the created label */ |
94 | return L; |
95 | } |
96 | |
97 | |
98 | |
99 | ExprNode* ULabRef (int Which) |
100 | /* Get an unnamed label. If Which is negative, it is a backreference (a |
101 | ** reference to an already defined label), and the function will return a |
102 | ** segment relative expression. If Which is positive, it is a forward ref, |
103 | ** and the function will return a expression node for an unnamed label that |
104 | ** must be resolved later. |
105 | */ |
106 | { |
107 | int Index; |
108 | ULabel* L; |
109 | |
110 | /* Which can never be 0 */ |
111 | PRECONDITION (Which != 0); |
112 | |
113 | /* Get the index of the referenced label */ |
114 | if (Which > 0) { |
115 | --Which; |
116 | } |
117 | Index = (int) ULabDefCount + Which; |
118 | |
119 | /* We cannot have negative label indices */ |
120 | if (Index < 0) { |
121 | /* Label does not exist */ |
122 | Error ("Undefined label" ); |
123 | /* We must return something valid */ |
124 | return GenCurrentPC(); |
125 | } |
126 | |
127 | /* Check if the label exists. If not, generate enough forward labels. */ |
128 | if (Index < (int) CollCount (&ULabList)) { |
129 | /* The label exists, get it. */ |
130 | L = CollAtUnchecked (&ULabList, Index); |
131 | } else { |
132 | /* Generate new, undefined labels */ |
133 | while (Index >= (int) CollCount (&ULabList)) { |
134 | L = NewULabel (0); |
135 | } |
136 | } |
137 | |
138 | /* Mark the label as referenced */ |
139 | ++L->Ref; |
140 | |
141 | /* If the label is already defined, return its value, otherwise return |
142 | ** just a reference. |
143 | */ |
144 | if (L->Val) { |
145 | return CloneExpr (L->Val); |
146 | } else { |
147 | return GenULabelExpr (Index); |
148 | } |
149 | } |
150 | |
151 | |
152 | |
153 | void ULabDef (void) |
154 | /* Define an unnamed label at the current PC */ |
155 | { |
156 | if (ULabDefCount < CollCount (&ULabList)) { |
157 | /* We did already have a forward reference to this label, so has |
158 | ** already been generated, but doesn't have a value. Use the current |
159 | ** PC for the label value. |
160 | */ |
161 | ULabel* L = CollAtUnchecked (&ULabList, ULabDefCount); |
162 | CHECK (L->Val == 0); |
163 | L->Val = GenCurrentPC (); |
164 | ReleaseFullLineInfo (&L->LineInfos); |
165 | GetFullLineInfo (&L->LineInfos); |
166 | } else { |
167 | /* There is no such label, create it */ |
168 | NewULabel (GenCurrentPC ()); |
169 | } |
170 | |
171 | /* We have one more defined label */ |
172 | ++ULabDefCount; |
173 | } |
174 | |
175 | |
176 | |
177 | int ULabCanResolve (void) |
178 | /* Return true if we can resolve arbitrary ULabels. */ |
179 | { |
180 | /* We can resolve labels if we don't have any undefineds */ |
181 | return (ULabDefCount == CollCount (&ULabList)); |
182 | } |
183 | |
184 | |
185 | |
186 | ExprNode* ULabResolve (unsigned Index) |
187 | /* Return a valid expression for the unnamed label with the given index. This |
188 | ** is used to resolve unnamed labels when assembly is done, so it is an error |
189 | ** if a label is still undefined in this phase. |
190 | */ |
191 | { |
192 | /* Get the label and check that it is defined */ |
193 | ULabel* L = CollAt (&ULabList, Index); |
194 | CHECK (L->Val != 0); |
195 | |
196 | /* Return the label value */ |
197 | return CloneExpr (L->Val); |
198 | } |
199 | |
200 | |
201 | |
202 | void ULabDone (void) |
203 | /* Run through all unnamed labels, check for anomalies and errors and do |
204 | ** necessary cleanups. |
205 | */ |
206 | { |
207 | /* Check if there are undefined labels */ |
208 | unsigned I = ULabDefCount; |
209 | while (I < CollCount (&ULabList)) { |
210 | ULabel* L = CollAtUnchecked (&ULabList, I); |
211 | LIError (&L->LineInfos, "Undefined label" ); |
212 | ++I; |
213 | } |
214 | |
215 | /* Walk over all labels and emit a warning if any unreferenced ones |
216 | ** are found. Remove line infos because they're no longer needed. |
217 | */ |
218 | for (I = 0; I < CollCount (&ULabList); ++I) { |
219 | ULabel* L = CollAtUnchecked (&ULabList, I); |
220 | if (L->Ref == 0) { |
221 | LIWarning (&L->LineInfos, 1, "No reference to unnamed label" ); |
222 | } |
223 | ReleaseFullLineInfo (&L->LineInfos); |
224 | } |
225 | } |
226 | |