Change file_util so that contents can be saved to disk.

Add new skip_to_sequence function for cassettes.

Change the way cassettes are read for better error handling.

Fix problem with granule allocation, fix README

Add different types of pre-ambles to disk functions.

Fix pre and post amble reading and writing.

Fix various portions of preambles.

Fix issues with saving chunks to disk.

Add preamble type for ASCII files.

Add unit tests for listing multiple files of different types.

README.md

@@ -127,9 +127,9 @@ that are available:
 
 * `--print` - prints out the assembled statements
 * `--symbols` - prints out the symbol table
-* `--bin_file` - save assembled contents to a binary file
-* `--cas_file` - save assembled contents to a cassette file
-* `--dsk_file` - save assembled contents to a virtual disk file
+* `--to_bin` - save assembled contents to a binary file
+* `--to_cas` - save assembled contents to a cassette file
+* `--to_dsk` - save assembled contents to a virtual disk file
 * `--name` - saves the program with the specified name on a cassette or virtual disk file
 
 ---
@@ -240,9 +240,9 @@ The columns are as follows:
 
 ### Save to Binary File
 
-To save the assembled contents to a binary file, use the `--bin_file` switch:
+To save the assembled contents to a binary file, use the `--to_bin` switch:
 
-    python3 assembler.py test.asm --bin_file test.bin
+    python3 assembler.py test.asm --to_bin test.bin
 
 The assembled program will be saved to the file `test.bin`. Note that this file
 may not be useful on its own, as it does not have any meta information about
@@ -255,9 +255,9 @@ will not have any effect on the assembled file).
 
 ### Save to Cassette File
 
-To save the assembled contents to a cassette file, use the `--cas_file` switch:
+To save the assembled contents to a cassette file, use the `--to_cas` switch:
 
-    python3 assembler.py test.asm --cas_file test.cas
+    python3 assembler.py test.asm --to_cas test.cas
 
 This will assemble the program and save it to a cassette file called `test.cas`.
 The source code must include the `NAM` mnemonic to name the program (e.g. 
@@ -268,7 +268,7 @@ The source code must include the `NAM` mnemonic to name the program (e.g.
 not be overwritten. If you wish to add the program to `test.cas`, you must 
 specify the `--append` flag during assembly:
 
-    python3 assembler.py test.asm --cas_file test.cas --append
+    python3 assembler.py test.asm --to_cas test.cas --append
 
 To load from the cassette file, you must use BASIC's `CLOADM` command as follows:
 
@@ -278,9 +278,9 @@ To load from the cassette file, you must use BASIC's `CLOADM` command as follows
 
 ### Save to Disk File
 
-To save the assembled contents to a disk file, use the `--dsk_file` switch:
+To save the assembled contents to a disk file, use the `--to_dsk` switch:
 
-    python3 assembler.py test.asm --dsk_file test.dsk
+    python3 assembler.py test.asm --to_dsk test.dsk
 
 This will assemble the program and save it to a disk file called `test.dsk`. 
 The source code must include the `NAM` mnemonic to name the program on disk (e.g.
@@ -291,7 +291,7 @@ The source code must include the `NAM` mnemonic to name the program on disk (e.g
 not be updated. If you wish to add the program to `test.dsk`, you must specify the 
 `--append` flag during assembly:
 
-    python3 assembler.py test.asm --dsk_file test.dsk --append
+    python3 assembler.py test.asm --to_dsk test.dsk --append
 
 To load from the disk file, you must use Disk Basic's `LOADM` command as follows:
 

assembler.py

@@ -38,13 +38,13 @@ def parse_arguments():
         help="print out the assembled statements when finished"
     )
     parser.add_argument(
-        "--bin_file", metavar="BIN_FILE", help="stores the assembled program in a binary BIN_FILE"
+        "--to_bin", metavar="BIN_FILE", help="stores the assembled program in a binary BIN_FILE"
     )
     parser.add_argument(
-        "--cas_file", metavar="CAS_FILE", help="stores the assembled program in a cassette image CAS_FILE"
+        "--to_cas", metavar="CAS_FILE", help="stores the assembled program in a cassette image CAS_FILE"
     )
     parser.add_argument(
-        "--dsk_file", metavar="DSK_FILE", help="stores the assembled program in a disk image DSK_FILE"
+        "--to_dsk", metavar="DSK_FILE", help="stores the assembled program in a disk image DSK_FILE"
     )
     parser.add_argument(
         "--name", help="the name of the file to be created on the cassette or disk image"
@@ -107,10 +107,10 @@ def main(args):
         for statement in program.get_statements():
             print(statement)
 
-    if args.bin_file:
+    if args.to_bin:
         try:
             virtual_file = VirtualFile(
-                SourceFile(args.bin_file, file_type=SourceFileType.BINARY),
+                SourceFile(args.to_bin, file_type=SourceFileType.BINARY),
                 VirtualFileType.BINARY
             )
             virtual_file.open_virtual_file()
@@ -120,13 +120,13 @@ def main(args):
             print("Unable to save binary file:")
             print(error)
 
-    if args.cas_file:
+    if args.to_cas:
         if not coco_file.name:
             print("No name for the program specified, not creating cassette file")
             return
         try:
             virtual_file = VirtualFile(
-                SourceFile(args.cas_file, file_type=SourceFileType.BINARY),
+                SourceFile(args.to_cas, file_type=SourceFileType.BINARY),
                 VirtualFileType.CASSETTE
             )
             virtual_file.open_virtual_file()
@@ -136,13 +136,13 @@ def main(args):
             print("Unable to save cassette file:")
             print(error)
 
-    if args.dsk_file:
+    if args.to_dsk:
         if not coco_file.name:
             print("No name for the program specified, not creating disk file")
             return
         try:
             virtual_file = VirtualFile(
-                SourceFile(args.dsk_file, file_type=SourceFileType.BINARY),
+                SourceFile(args.to_dsk, file_type=SourceFileType.BINARY),
                 VirtualFileType.DISK
             )
             virtual_file.open_virtual_file()