Autoadjust BASIC start offset based on filesize. Emit warnings, error.

If the final tokenized program is

	>= 65536 bytes long, then die with an error.

	>= 32768 bytes, then warn that it will work on no actual
	                hardware and set offset to 0. (It probably
	                won't work on any virtual hardware, either.)

	>= 24576 bytes, then warn about Tandy 200 incompatibility and
	                set offset to 0x8001.

Author: hackerb9

m100-tokenize-main.c

@@ -74,9 +74,30 @@ int fixup_ptrs() {
   /* Offset into RAM for start of the first BASIC program.
      0x8001: Used by Model 100, Tandy 102, Kyocera-85, and Olivetti M10.
      0xA001: Used by Tandy 200 (which has more ROM and less RAM). */
-  int offset = 0x8001;
+  long offset = 0x8001;
 
-  ptr[nlines++] = ftell(yyout);	/* Pointer to final NULL byte */
+  long filesize = ftell(yyout);	/* Pointer to final NULL byte */
+  ptr[nlines++] = filesize;
+
+  /* Double-check size of .BA file */
+  fprintf(stderr, "file size is 0x%x\n", filesize);
+  if ( filesize >= 0x10000 ) {
+    fprintf(stderr, "Fatal Error. Program too large to fit in 64K RAM.\n");
+    fprintf(stderr, "Due to 16-bit pointers in BASIC, this cannot work.\n");
+    exit(1);
+  }
+  else if ( filesize >= 0x8000 ) {
+    fprintf(stderr, "Warning. Program too large to fit in 32K RAM.\n");
+    fprintf(stderr, "The output cannot run on any standard hardware.\n");
+    if ( filesize+offset >= 0x10000 )
+      offset=0;
+  }
+  else if ( filesize >= 0x6000 ) {
+    fprintf(stderr, "Notice. Program too large to fit in 24K RAM.\n");
+    fprintf(stderr, "The output cannot run on a standard Tandy 200.\n");
+    if ( filesize+offset >= 0x10000 )
+      offset=0x8001;
+  }    
 
   if (fseek(yyout, 0L, SEEK_SET) != 0) {
     perror("fseek");

m100-tokenize.lex

@@ -29,10 +29,6 @@
 %%
 
 ^[[:space:]]*[0-9]+[ ]?	{
-    if (ftell(yyout) >= 0x8000) {
-        fprintf(stderr, "Program too large to fit in 32K RAM\n");
-        exit(1);
-    }
     ptr[nlines++] = ftell(yyout);   /* Cache the location of the current line */
     yyput('*'); yyput('*');	    /* Dummy placeholder pointer to next line.*/
     uint16_t linenum=atoi(yytext);  /* BASIC line number. */