Implemented file saving

.gitignore

@@ -0,0 +1 @@
+/vgmparse/__pycache__

.project

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<projectDescription>
+	<name>vgmparse</name>
+	<comment></comment>
+	<projects>
+	</projects>
+	<buildSpec>
+		<buildCommand>
+			<name>org.python.pydev.PyDevBuilder</name>
+			<arguments>
+			</arguments>
+		</buildCommand>
+	</buildSpec>
+	<natures>
+		<nature>org.python.pydev.pythonNature</nature>
+	</natures>
+</projectDescription>

.pydevproject

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<?eclipse-pydev version="1.0"?><pydev_project>
+<pydev_property name="org.python.pydev.PYTHON_PROJECT_INTERPRETER">Default</pydev_property>
+<pydev_property name="org.python.pydev.PYTHON_PROJECT_VERSION">python 2.7</pydev_property>
+<pydev_pathproperty name="org.python.pydev.PROJECT_SOURCE_PATH">
+<path>/${PROJECT_DIR_NAME}</path>
+</pydev_pathproperty>
+</pydev_project>

README.md

@@ -2,7 +2,7 @@
 A Python module for parsing [VGM (Video Game Music)](https://en.wikipedia.org/wiki/VGM_(file_format))
 files. `.vgm` and `.vgz` (Gzip compressed) files are supported.
 
-Currently, only version 1.50 of the VGM specification is supported.
+Currently, only versions 1.01 and 1.50 of the VGM specification are supported.
 
 ## Installation
 The `vgmparse` module can be installed directly from GitHub using `pip`:
@@ -79,3 +79,12 @@ then seek and read like a file:
 @>>> vgm_data.data_block.read(5)
 b'\x82\x88\x8a\x8a\x88'
 ```
+
+### Saving a VGM file
+
+You can save the VGM back into a file by using the `.save()` method:
+
+```
+@>>> vgm_out = open('newfile.vgm', 'wb')
+@>>> vgm_data.save(vgm_out)
+```

test/test.py

@@ -0,0 +1,29 @@
+import unittest
+import vgmparse
+import tempfile, time
+
+class TestParsing(unittest.TestCase):
+
+    def test_vgm_1_01(self):
+        with open('Alex Kidd in Miracle World - 01 - Title Screen.vgm', 'rb') as f:
+            file_data = f.read()
+            parser = vgmparse.Parser(file_data)
+
+            # The first command is a GG Stereo command
+            self.assertEqual(0x4F, ord(parser.command_list[0]['command']))
+            self.assertEqual(0xFF, ord(parser.command_list[0]['data']))
+
+            # The second command is a SN76496 Latch/Data command
+            self.assertEqual(0x50, ord(parser.command_list[1]['command']))
+            self.assertEqual(0x80, ord(parser.command_list[1]['data']))
+
+    def test_save(self):
+        with open('Alex Kidd in Miracle World - 01 - Title Screen.vgm', 'rb') as f:
+            file_data = f.read()
+            parser = vgmparse.Parser(file_data)
+
+            with open('{0}/test-save-{1}.vgm'.format(tempfile.gettempdir(), time.time()), 'wb') as o:
+                parser.save(o)
+
+if __name__ == '__main__':
+    unittest.main()

vgmparse/__init__.py

@@ -18,41 +18,39 @@ class Parser:
 
     # Supported VGM versions
     supported_ver_list = [
+        0x00000101,
         0x00000150,
     ]
 
     # VGM metadata offsets
     metadata_offsets = {
-        # Version 1.50
-        0x00000150: {
-            'vgm_ident': {'offset': 0x00, 'size': 4, 'type_format': None},
-            'eof_offset': {'offset': 0x04, 'size': 4, 'type_format': '<I'},
-            'version': {'offset': 0x08, 'size': 4, 'type_format': '<I'},
-            'sn76489_clock': {'offset': 0x0c, 'size': 4, 'type_format': '<I'},
-            'ym2413_clock': {'offset': 0x10, 'size': 4, 'type_format': '<I'},
-            'gd3_offset': {'offset': 0x14, 'size': 4, 'type_format': '<I'},
-            'total_samples': {'offset': 0x18, 'size': 4, 'type_format': '<I'},
-            'loop_offset': {'offset': 0x1c, 'size': 4, 'type_format': '<I'},
-            'loop_samples': {'offset': 0x20, 'size': 4, 'type_format': '<I'},
-            'rate': {'offset': 0x24, 'size': 4, 'type_format': '<I'},
-            'sn76489_feedback': {
-                'offset': 0x28,
-                'size': 2,
-                'type_format': '<H',
-            },
-            'sn76489_shift_register_width': {
-                'offset': 0x2a,
-                'size': 1,
-                'type_format': 'B',
-            },
-            'ym2612_clock': {'offset': 0x2c, 'size': 4, 'type_format': '<I'},
-            'ym2151_clock': {'offset': 0x30, 'size': 4, 'type_format': '<I'},
-            'vgm_data_offset': {
-                'offset': 0x34,
-                'size': 4,
-                'type_format': '<I',
-            },
-        }
+        'vgm_ident': {'offset': 0x00, 'size': 4, 'type_format': None},
+        'eof_offset': {'offset': 0x04, 'size': 4, 'type_format': '<I'},
+        'version': {'offset': 0x08, 'size': 4, 'type_format': '<I'},
+        'sn76489_clock': {'offset': 0x0c, 'size': 4, 'type_format': '<I'},
+        'ym2413_clock': {'offset': 0x10, 'size': 4, 'type_format': '<I'},
+        'gd3_offset': {'offset': 0x14, 'size': 4, 'type_format': '<I'},
+        'total_samples': {'offset': 0x18, 'size': 4, 'type_format': '<I'},
+        'loop_offset': {'offset': 0x1c, 'size': 4, 'type_format': '<I'},
+        'loop_samples': {'offset': 0x20, 'size': 4, 'type_format': '<I'},
+        'rate': {'offset': 0x24, 'size': 4, 'type_format': '<I'},
+        'sn76489_feedback': {
+            'offset': 0x28,
+            'size': 2,
+            'type_format': '<H',
+        },
+        'sn76489_shift_register_width': {
+            'offset': 0x2a,
+            'size': 1,
+            'type_format': 'B',
+        },
+        'ym2612_clock': {'offset': 0x2c, 'size': 4, 'type_format': '<I'},
+        'ym2151_clock': {'offset': 0x30, 'size': 4, 'type_format': '<I'},
+        'vgm_data_offset': {
+            'offset': 0x34,
+            'size': 4,
+            'type_format': '<I',
+        },
     }
 
     def __init__(self, vgm_data):
@@ -81,7 +79,7 @@ def parse_commands(self):
         # Seek to the start of the VGM data
         self.data.seek(
             self.metadata['vgm_data_offset'] +
-            self.metadata_offsets[self.metadata['version']]['vgm_data_offset']['offset']
+            self.metadata_offsets['vgm_data_offset']['offset']
         )
 
         while True:
@@ -164,7 +162,7 @@ def parse_gd3(self):
         # Seek to the start of the GD3 data
         self.data.seek(
             self.metadata['gd3_offset'] +
-            self.metadata_offsets[self.metadata['version']]['gd3_offset']['offset']
+            self.metadata_offsets['gd3_offset']['offset']
         )
 
         # Skip 8 bytes ('Gd3 ' string and 4 byte version identifier)
@@ -220,21 +218,20 @@ def parse_metadata(self):
         self.metadata = {}
 
         # Iterate over the offsets and parse the metadata
-        for version, offsets in self.metadata_offsets.items():
-            for value, offset_data in offsets.items():
-
-                # Seek to the data location and read the data
-                self.data.seek(offset_data['offset'])
-                data = self.data.read(offset_data['size'])
-
-                # Unpack the data if required
-                if offset_data['type_format'] is not None:
-                    self.metadata[value] = struct.unpack(
-                        offset_data['type_format'],
-                        data,
-                    )[0]
-                else:
-                    self.metadata[value] = data
+        for value, offset_data in self.metadata_offsets.items():
+
+            # Seek to the data location and read the data
+            self.data.seek(offset_data['offset'])
+            data = self.data.read(offset_data['size'])
+
+            # Unpack the data if required
+            if offset_data['type_format'] is not None:
+                self.metadata[value] = struct.unpack(
+                    offset_data['type_format'],
+                    data,
+                )[0]
+            else:
+                self.metadata[value] = data
 
         # Seek back to the original position in the VGM data
         self.data.seek(original_pos)
@@ -266,4 +263,36 @@ def validate_vgm_data(self):
 
     def validate_vgm_version(self):
         if self.metadata['version'] not in self.supported_ver_list:
-            raise VersionError('VGM version is not supported')
+            raise VersionError('VGM version %s is not supported' % self.version_str())
+
+    def version_str(self):
+        version = self.metadata['version']
+        return '%01x.%02x' % (version >> 8, version & 0xFF)
+
+    def save(self, buffer):
+        # Pre-fill the header with zeroes
+        buffer.seek(0)
+        buffer.write(b'\0' * 0x40)
+
+        # Iterate over the offsets and write the metadata
+        for value, offset_data in self.metadata_offsets.items():
+
+            # Seek to the data location and read the data
+            buffer.seek(offset_data['offset'])
+
+            # Unpack the data if required
+            if offset_data['type_format'] is not None:
+                data = struct.pack(
+                    offset_data['type_format'],
+                    self.metadata[value],
+                )
+                buffer.write(data)
+            else:
+                buffer.write(self.metadata[value])
+
+        # Write out the commands
+        for cmd in self.command_list:
+            buffer.write(cmd['command'])
+            if cmd['data']:
+                buffer.write(cmd['data']) 
+