From 921cf9c521b64641f6364ef04b370979ce99fd64 Mon Sep 17 00:00:00 2001
From: "B. Watson" <urchlay@slackware.uk>
Date: Wed, 29 May 2024 03:31:23 -0400
Subject: unprotbas: code readability (constants), mention rev B BASIC in doc.

---
 unprotbas.c | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

(limited to 'unprotbas.c')

diff --git a/unprotbas.c b/unprotbas.c
index 6edb38f..37013cf 100644
--- a/unprotbas.c
+++ b/unprotbas.c
@@ -37,6 +37,11 @@
 /* tokenized colon (statement separator) */
 #define TOK_COLON 0x14
 
+/* variable types, bits 6-7 of byte 0 of each vvtable entry. */
+#define TYPE_SCALAR 0
+#define TYPE_ARRAY  1
+#define TYPE_STRING 2
+
 /* entire file gets read into memory (for now) */
 unsigned char data[BUFSIZE];
 
@@ -98,7 +103,7 @@ void die(const char *msg) {
 
 /* read entire file into memory */
 int readfile(void) {
-	int got = fread(data, 1, 65535, input_file);
+	int got = fread(data, 1, BUFSIZE - 1, input_file);
 	if(verbose) fprintf(stderr, "read %d bytes\n", got);
 	fclose(input_file);
 	if(got < MIN_PROG_SIZE)
@@ -282,7 +287,7 @@ void breakcode(void) {
 void move_code(int offset) {
 	unsigned char *dest = data + vvstart + offset;
 
-	if(dest < data || (filelen + offset) > 65535) {
+	if(dest < data || ((filelen + offset) > (BUFSIZE - 1))) {
 		die("attempt to move memory out of range; corrupt header bytes?\n");
 	}
 
@@ -394,9 +399,12 @@ int rebuild_vntable(int write) {
 		}
 
 		switch(type) {
-			case 1: varname = arrays++; sigil = 0xa8; break;
-			case 2: varname = strings++; sigil = 0xa4; break;
-			default: varname = scalars++; break;
+			case TYPE_SCALAR: varname = scalars++;               break;
+			case TYPE_ARRAY:  varname = arrays++;  sigil = 0xa8; break;
+			case TYPE_STRING: varname = strings++; sigil = 0xa4; break;
+			default:
+					  fprintf(stderr, "Warning: variable value #%d has unknown type.\n", varnum);
+					  break;
 		}
 
 		if(varname < 26) {
@@ -520,15 +528,15 @@ void check_varname(const unsigned char *name, int line) {
 	/* c now has the last char of the name, make sure it matches the variable type */
 	type = data[vvstart + 8 * (line - 1)] >> 6;
 	/* type: scalar = 0, array = 1, string = 2 */
-	if(type == 0) {
+	if(type == TYPE_SCALAR) {
 		if(c == '$')
 			die_mapfile("type mismatch: numeric variable may not end with $", line);
 		else if(c == '(')
 			die_mapfile("type mismatch: numeric variable may not end with (", line);
-	} else if(type == 1) {
+	} else if(type == TYPE_ARRAY) {
 		if(c != '(')
 			die_mapfile("type mismatch: array variable must end with (", line);
-	} else if(type == 2) {
+	} else if(type == TYPE_STRING) {
 		if(c != '$')
 			die_mapfile("type mismatch: string variable must end with $", line);
 	} else {
-- 
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