Release calc version 2.10.2t30

label.c

@@ -0,0 +1,186 @@
+/*
+ * Copyright (c) 1993 David I. Bell
+ * Permission is granted to use, distribute, or modify this source,
+ * provided that this copyright notice remains intact.
+ *
+ * Label handling routines.
+ */
+
+#include "calc.h"
+#include "token.h"
+#include "label.h"
+#include "string.h"
+#include "opcodes.h"
+#include "func.h"
+
+static long labelcount;			/* number of user labels defined */
+static STRINGHEAD labelnames;		/* list of user label names */
+static LABEL labels[MAXLABELS];		/* list of user labels */
+
+
+/*
+ * Initialize the table of labels for a function.
+ */
+void
+initlabels(void)
+{
+	labelcount = 0;
+	initstr(&labelnames);
+}
+
+
+/*
+ * Define a user named label to have the offset of the next opcode.
+ *
+ * given:
+ *	name		label name
+ */
+void
+definelabel(char *name)
+{
+	register LABEL *lp;		/* current label */
+	long i;				/* current label index */
+
+	i = findstr(&labelnames, name);
+	if (i >= 0) {
+		lp = &labels[i];
+		if (lp->l_offset) {
+			scanerror(T_NULL, "Label \"%s\" is multiply defined",
+				name);
+			return;
+		}
+		setlabel(lp);
+		return;
+	}
+	if (labelcount >= MAXLABELS) {
+		scanerror(T_NULL, "Too many labels in use");
+		return;
+	}
+	lp = &labels[labelcount++];
+	lp->l_chain = 0;
+	lp->l_offset = (long)curfunc->f_opcodecount;
+	lp->l_name = addstr(&labelnames, name);
+	clearopt();
+}
+
+
+/*
+ * Add the offset corresponding to the specified user label name to the
+ * opcode table for a function. If the label is not yet defined, then a
+ * chain of undefined offsets is built using the offset value, and it
+ * will be fixed up when the label is defined.
+ *
+ * given:
+ *	name		user symbol name
+ */
+void
+addlabel(char *name)
+{
+	register LABEL *lp;		/* current label */
+	long i;				/* counter */
+
+	for (i = labelcount, lp = labels; --i >= 0; lp++) {
+		if (strcmp(name, lp->l_name))
+			continue;
+		uselabel(lp);
+		return;
+	}
+	if (labelcount >= MAXLABELS) {
+		scanerror(T_NULL, "Too many labels in use");
+		return;
+	}
+	lp = &labels[labelcount++];
+	lp->l_offset = 0;
+	lp->l_chain = 0;
+	lp->l_name = addstr(&labelnames, name);
+	uselabel(lp);
+}
+
+
+/*
+ * Check to make sure that all labels are defined.
+ */
+void
+checklabels(void)
+{
+	register LABEL *lp;		/* label being checked */
+	long i;				/* counter */
+
+	for (i = labelcount, lp = labels; --i >= 0; lp++) {
+		if (lp->l_offset > 0)
+			continue;
+		scanerror(T_NULL, "Label \"%s\" was never defined",
+			lp->l_name);
+	}
+}
+
+
+/*
+ * Clear an internal label for use.
+ *
+ * given:
+ *	lp		label being cleared
+ */
+void
+clearlabel(LABEL *lp)
+{
+	lp->l_offset = 0;
+	lp->l_chain = 0;
+	lp->l_name = NULL;
+}
+
+
+/*
+ * Set any label to have the value of the next opcode in the current
+ * function being defined.  If there were forward references to it,
+ * all such references are patched up.
+ *
+ * given:
+ *	lp		label being set
+ */
+void
+setlabel(LABEL *lp)
+{
+	register FUNC *fp;	/* current function */
+	unsigned long curfix;	/* offset of current location being fixed */
+	unsigned long nextfix;	/* offset of next location to fix up */
+	unsigned long offset;	/* offset of this label */
+
+	fp = curfunc;
+	offset = fp->f_opcodecount;
+	nextfix = lp->l_chain;
+	while (nextfix > 0) {
+		curfix = nextfix;
+		nextfix = fp->f_opcodes[curfix];
+		fp->f_opcodes[curfix] = offset;
+	}
+	lp->l_chain = 0;
+	lp->l_offset = (long)offset;
+	clearopt();
+}
+
+
+/*
+ * Use the specified label at the current location in the function
+ * being compiled.  This adds one word to the current function being
+ * compiled.  If the label is not yet defined, a patch chain is built
+ * so the reference can be fixed when the label is defined.
+ *
+ * given:
+ *	lp		label being used
+ */
+void
+uselabel(LABEL *lp)
+{
+	unsigned long offset;		/* offset being added */
+
+	offset = curfunc->f_opcodecount;
+	if (lp->l_offset > 0) {
+		curfunc->f_opcodes[curfunc->f_opcodecount++] = lp->l_offset;
+		return;
+	}
+	curfunc->f_opcodes[curfunc->f_opcodecount++] = lp->l_chain;
+	lp->l_chain = (long)offset;
+}
+
+/* END CODE */