1 files changed, 165 insertions, 0 deletions
diff --git a/linetab.c b/linetab.c
new file mode 100644
index 0000000..c4fe392
--- /dev/null
+++ b/linetab.c
@@ -0,0 +1,165 @@
+#include "linetab.h"
+
+lineref_t *linerefs[32769];
+int refcounts[32769];
+int lines_exist[32769];
+unsigned char last_cmd, on_op;
+int last_cmd_pos;
+
+void add_lineref(unsigned short from, unsigned short pos) {
+	lineref_t *p;
+	int c;
+	unsigned short to;
+
+	to = fp2int(program + pos);
+	if(to > 32767) return;
+
+	p = linerefs[to];
+	c = refcounts[to];
+
+	if(c) {
+		p = realloc(p, sizeof(lineref_t) * (c + 1));
+	} else {
+		p = malloc(sizeof(lineref_t));
+	}
+
+	if(!p) die("Out of memory.");
+
+	linerefs[to] = p;
+	linerefs[to][c].lineno = from;
+	linerefs[to][c].pos = pos;
+	linerefs[to][c].cmd = last_cmd;
+	c++;
+	refcounts[to] = c;
+}
+
+/* makes sure a numeric constant isn't start of an expression. */
+int is_standalone_num(unsigned short pos) {
+	if(program[pos] != OP_NUMCONST) return 0;
+	switch(program[pos + 7]) {
+		case OP_EOS:
+		case OP_EOL:
+		case OP_COMMA:
+			return 1;
+		default:
+			return 0;
+	}
+}
+
+CALLBACK(start_stmt) {
+	lines_exist[lineno] = 1;
+}
+
+CALLBACK(got_cmd) {
+	last_cmd = tok;
+	last_cmd_pos = pos;
+	on_op = 0;
+}
+
+void computed_msg(unsigned short lineno) {
+	static int last_lineno = -1;
+	char *cmd;
+
+	/* avoid duplicate warnings */
+	if(lineno == last_lineno) return;
+	last_lineno = lineno;
+
+	switch(last_cmd) {
+		case CMD_GOTO:
+			cmd = "GOTO"; break;
+		case CMD_GO_TO:
+			cmd = "GO TO"; break;
+		case CMD_GOSUB:
+			cmd = "GOSUB"; break;
+		case CMD_RESTORE:
+			cmd = "RESTORE"; break;
+		case CMD_TRAP:
+			cmd = "TRAP"; break;
+			/*
+		case CMD_IF:
+			cmd = "IF/THEN"; break;
+			*/
+		case CMD_ON:
+			if(on_op == OP_GOSUB)
+				cmd = "ON/GOSUB";
+			else
+				cmd = "ON/GOTO";
+			break;
+		default: /* should never happen! */
+			cmd = "???"; break;
+	}
+
+	fprintf(stderr, "Computed %s at line %d\n", cmd, lineno);
+}
+
+CALLBACK(got_var) {
+	switch(last_cmd) {
+		case CMD_GOTO:
+		case CMD_GO_TO:
+		case CMD_GOSUB:
+		case CMD_RESTORE:
+		case CMD_TRAP:
+			computed_msg(lineno);
+			break;
+		default:
+			break;
+	}
+}
+
+CALLBACK(got_exp) {
+	unsigned char last_tok = program[pos - 1];
+	int standalone;
+
+	if(last_cmd == CMD_ON) {
+		if(tok == OP_GOTO || tok == OP_GOSUB)
+			on_op = tok;
+	}
+
+	if(tok != OP_NUMCONST) return;
+	standalone = is_standalone_num(pos);
+
+	switch(last_cmd) {
+		case CMD_GOTO:
+		case CMD_GO_TO:
+		case CMD_GOSUB:
+		case CMD_RESTORE:
+		case CMD_TRAP:
+			if((pos == last_cmd_pos + 1) && standalone) {
+				add_lineref(lineno, pos + 1);
+			} else {
+				computed_msg(lineno);
+			}
+			break;
+		case CMD_IF:
+			if(last_tok == OP_THEN) {
+				add_lineref(lineno, pos + 1);
+			}
+			break;
+		case CMD_ON: {
+				switch(last_tok) {
+					case OP_GOTO:
+					case OP_GOSUB:
+					case OP_COMMA:
+						if(standalone)
+							add_lineref(lineno, pos + 1);
+						else
+							computed_msg(lineno);
+						break;
+					default:
+						break;
+				}
+			}
+			break;
+		default:
+			break;
+	}
+}
+
+void build_ref_table(void) {
+	on_start_stmt = start_stmt;
+	on_cmd_token = got_cmd;
+	on_exp_token = got_exp;
+	on_var_token = got_var;
+	walk_all_code();
+}
+