1 /*****************************************************************************/
5 /* Parse the switch statement */
9 /* (C) 1998-2003 Ullrich von Bassewitz */
11 /* D-70597 Stuttgart */
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 /*****************************************************************************/
58 /*****************************************************************************/
60 /*****************************************************************************/
64 void SwitchStatement (void)
65 /* Handle a switch statement for chars with a cmp cascade for the selector */
67 Collection* Nodes; /* CaseNode tree */
68 ExprDesc SwitchExpr; /* Switch statement expression */
69 ExprDesc CaseExpr; /* Case label expression */
70 type SwitchExprType; /* Basic switch expression type */
71 CodeMark CaseCodeStart; /* Start of code marker */
72 unsigned Depth; /* Number of bytes the selector type has */
73 unsigned ExitLabel; /* Exit label */
74 unsigned CaseLabel; /* Label for case */
75 unsigned DefaultLabel; /* Label for the default branch */
76 unsigned SwitchCodeLabel; /* Label for the switch code */
77 long Val; /* Case label value */
78 int HaveBreak = 0; /* True if the last statement had a break */
81 /* Eat the "switch" token */
84 /* Read the switch expression */
86 intexpr (&SwitchExpr);
89 /* Add a jump to the switch code. This jump is usually unnecessary,
90 * because the switch code will moved up just behind the switch
91 * expression. However, in rare cases, there's a label at the end of
92 * the switch expression. This label will not get moved, so the code
93 * jumps around the switch code, and after moving the switch code,
94 * things look really weird. If we add a jump here, we will never have
95 * a label attached to the current code position, and the jump itself
96 * will get removed by the optimizer if it is unnecessary.
98 SwitchCodeLabel = GetLocalLabel ();
99 g_jump (SwitchCodeLabel);
101 /* Remember the current code position. We will move the switch code
102 * to this position later.
104 CaseCodeStart = GetCodePos();
106 /* Opening curly brace */
109 /* Get the unqualified type of the switch expression */
110 SwitchExprType = UnqualifiedType (SwitchExpr.Type[0]);
112 /* Get the number of bytes the selector type has */
113 Depth = SizeOf (SwitchExpr.Type);
114 CHECK (Depth == 1 || Depth == 2 || Depth == 4);
116 /* Get the exit label for the switch statement */
117 ExitLabel = GetLocalLabel ();
119 /* Create a loop so we may use break. */
120 AddLoop (oursp, 0, ExitLabel, 0, 0);
122 /* Create the collection for the case node tree */
123 Nodes = NewCollection ();
125 /* Clear the label for the default branch */
128 /* Parse the labels */
129 while (CurTok.Tok != TOK_RCURLY) {
131 while (CurTok.Tok == TOK_CASE || CurTok.Tok == TOK_DEFAULT) {
133 /* Parse the selector */
134 if (CurTok.Tok == TOK_CASE) {
136 /* Skip the "case" token */
139 /* Read the selector expression */
140 ConstExpr (&CaseExpr);
141 if (!IsClassInt (CaseExpr.Type)) {
142 Error ("Switch quantity not an integer");
145 /* Check the range of the expression */
146 Val = CaseExpr.ConstVal;
147 switch (SwitchExprType) {
151 if (Val < -128 || Val > 127) {
152 Error ("Range error");
157 if (Val < 0 || Val > 255) {
158 Error ("Range error");
164 if (Val < -32768 || Val > 32767) {
165 Error ("Range error");
171 if (Val < 0 || Val > 65535) {
172 Error ("Range error");
181 Internal ("Invalid type: %04X", SwitchExprType);
184 /* Insert the case selector into the selector table */
185 CaseLabel = InsertCaseValue (Nodes, Val, Depth);
187 /* Define this label */
188 g_defcodelabel (CaseLabel);
198 /* Check if we do already have a default branch */
199 if (DefaultLabel == 0) {
201 /* Generate and emit the default label */
202 DefaultLabel = GetLocalLabel ();
203 g_defcodelabel (DefaultLabel);
206 /* We had the default label already */
207 Error ("Duplicate `default' case");
217 /* Parse statements */
218 if (CurTok.Tok != TOK_RCURLY) {
219 HaveBreak = Statement (0);
223 /* Check if we had any labels */
224 if (CollCount (Nodes) == 0 && DefaultLabel == 0) {
226 Warning ("No case labels");
230 CodeMark SwitchCodeStart;
232 /* If the last statement did not have a break, we may have an open
233 * label (maybe from an if or similar). Emitting code and then moving
234 * this code to the top will also move the label to the top which is
235 * wrong. So if the last statement did not have a break (which would
236 * carry the label), add a jump to the exit. If it is useless, the
237 * optimizer will remove it later.
243 /* Remember the current position */
244 SwitchCodeStart = GetCodePos();
246 /* Output the switch code label */
247 g_defcodelabel (SwitchCodeLabel);
250 g_switch (Nodes, DefaultLabel? DefaultLabel : ExitLabel, Depth);
252 /* Move the code to the front */
253 MoveCode (SwitchCodeStart, GetCodePos(), CaseCodeStart);
257 /* Define the exit label */
258 g_defcodelabel (ExitLabel);
260 /* Eat the closing curly brace */
263 /* Free the case value tree */
264 FreeCaseNodeColl (Nodes);