*** empty log message ***

lang/cem/cemcom/switch.c

@@ -0,0 +1,184 @@
+/* $Header$ */
+/*	S W I T C H - S T A T E M E N T  A D M I N I S T R A T I O N	*/
+
+#include	"debug.h"
+#include	"botch_free.h"
+#include	"density.h"
+
+#include	"idf.h"
+#include	"label.h"
+#include	"arith.h"
+#include	"switch.h"
+#include	"code.h"
+#include	"storage.h"
+#include	"assert.h"
+#include	"expr.h"
+#include	"type.h"
+#include	"em.h"
+
+#define	compact(nr, low, up)	(nr != 0 && (up - low) / nr <= (DENSITY - 1))
+
+static struct switch_hdr *switch_stack = 0;
+
+code_startswitch(expr)
+	struct expr *expr;
+{
+	/*	stack a new case header and fill in the necessary fields.
+	*/
+	register label l_table = text_label();
+	register label l_break = text_label();
+	register struct switch_hdr *sh = new_switch_hdr();
+
+	stat_stack(l_break, NO_LABEL);
+	sh->sh_break = l_break;
+	sh->sh_default = 0;
+	sh->sh_table = l_table;
+	sh->sh_nrofentries = 0;
+	sh->sh_type = expr->ex_type;	/* the expression switched	*/
+	sh->sh_lowerbd = sh->sh_upperbd = (arith)0;	/* ??? */
+	sh->sh_entries = (struct case_entry *) 0; /* case-entry list	*/
+	sh->next = switch_stack;	/* push onto switch-stack	*/
+	switch_stack = sh;
+	code_expr(expr, RVAL, TRUE, NO_LABEL, NO_LABEL);
+					/* evaluate the switch expr.	*/
+	C_bra(l_table);			/* goto start of switch_table	*/
+}
+
+code_endswitch()
+{
+	register struct switch_hdr *sh = switch_stack;
+	register label tablabel;
+	register struct case_entry *ce, *tmp;
+
+	if (sh->sh_default == 0)	/* no default occurred yet */
+		sh->sh_default = sh->sh_break;
+	C_bra(sh->sh_break);		/* skip the switch table now	*/
+	C_ilb(sh->sh_table);		/* switch table entry		*/
+	tablabel = data_label();	/* the rom must have a label	*/
+	C_ndlb(tablabel);
+	C_rom_begin();
+	C_co_ilb(sh->sh_default);
+	if (compact(sh->sh_nrofentries, sh->sh_lowerbd, sh->sh_upperbd)) {
+		/* CSA */
+		register arith val;
+
+		C_co_cst(sh->sh_lowerbd);
+		C_co_cst(sh->sh_upperbd - sh->sh_lowerbd);
+		ce = sh->sh_entries;
+		for (val = sh->sh_lowerbd; val <= sh->sh_upperbd; val++) {
+			ASSERT(ce);
+			if (val == ce->ce_value)	{
+				C_co_ilb(ce->ce_label);
+				ce = ce->next;
+			}
+			else
+				C_co_ilb(sh->sh_default);
+		}
+		C_rom_end();
+		C_lae_ndlb(tablabel, (arith)0); /* perform the switch	*/
+		C_csa(sh->sh_type->tp_size);
+	}
+	else	{ /* CSB */
+		C_co_cst((arith)sh->sh_nrofentries);
+		for (ce = sh->sh_entries; ce; ce = ce->next)	{
+			/* generate the entries: value + prog.label	*/
+			C_co_cst(ce->ce_value);
+			C_co_ilb(ce->ce_label);
+		}
+		C_rom_end();
+		C_lae_ndlb(tablabel, (arith)0); /* perform the switch	*/
+		C_csb(sh->sh_type->tp_size);
+	}
+	C_ilb(sh->sh_break);
+	switch_stack = sh->next;	/* unstack the switch descriptor */
+	/* free the allocated switch structure	*/
+	for (ce = sh->sh_entries; ce; ce = tmp)	{
+		tmp = ce->next;
+		free_case_entry(ce);
+	}
+	free_switch_hdr(sh);
+	stat_unstack();
+}
+
+code_case(val)
+	arith val;
+{
+	register struct case_entry *ce;
+	register struct switch_hdr *sh = switch_stack;
+
+	if (sh == 0)	{
+		error("case statement not in switch");
+		return;
+	}
+	ce = new_case_entry();
+	C_ilb(ce->ce_label = text_label());
+	ce->ce_value = val;
+	if (sh->sh_entries == 0)	{
+		/* first case entry	*/
+		ce->next = (struct case_entry *) 0;
+		sh->sh_entries = ce;
+		sh->sh_lowerbd = sh->sh_upperbd = ce->ce_value;
+		sh->sh_nrofentries = 1;
+	}
+	else	{
+		/* second etc. case entry		*/
+		/* find the proper place to put ce into the list	*/
+		register struct case_entry *c1 = sh->sh_entries, *c2 = 0;
+		
+		if (val < sh->sh_lowerbd)
+			sh->sh_lowerbd = val;
+		else
+		if (val > sh->sh_upperbd)
+			sh->sh_upperbd = val;
+		while (c1 && c1->ce_value < ce->ce_value)	{
+			c2 = c1;
+			c1 = c1->next;
+		}
+		/*	At this point three cases are possible:
+			1: c1 != 0 && c2 != 0:
+				insert ce somewhere in the middle
+			2: c1 != 0 && c2 == 0:
+				insert ce right after the head
+			3: c1 == 0 && c2 != 0:
+				append ce to last element
+			The case c1 == 0 && c2 == 0 cannot occur!
+		*/
+		if (c1)	{
+			if (c1->ce_value == ce->ce_value)	{
+				error("multiple case entry for value %ld",
+					ce->ce_value);
+				free_case_entry(ce);
+				return;
+			}
+			if (c2)	{
+				ce->next = c2->next;
+				c2->next = ce;
+			}
+			else	{
+				ce->next = sh->sh_entries;
+				sh->sh_entries = ce;
+			}
+		}
+		else	{
+			ASSERT(c2);
+			ce->next = (struct case_entry *) 0;
+			c2->next = ce;
+		}
+		(sh->sh_nrofentries)++;
+	}
+}
+
+code_default()
+{
+	register struct switch_hdr *sh = switch_stack;
+
+	if (sh == 0)	{
+		error("default not in switch");
+		return;
+	}
+	if (sh->sh_default != 0)	{
+		error("multiple entry for default in switch");
+		return;
+	}
+	C_ilb(sh->sh_default = text_label());
+}