Initial commit

.gitignore

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+# Byte-compiled / optimized / DLL files / pip / IDE
+__pycache__/
+*.py[cod]
+*$py.class
+src/
+.idea/
+*.n64
+*.v64
+*.z64

LICENSE

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+This is free and unencumbered software released into the public domain.
+
+Anyone is free to copy, modify, publish, use, compile, sell, or
+distribute this software, either in source code form or as a compiled
+binary, for any purpose, commercial or non-commercial, and by any
+means.
+
+In jurisdictions that recognize copyright laws, the author or authors
+of this software dedicate any and all copyright interest in the
+software to the public domain. We make this dedication for the benefit
+of the public at large and to the detriment of our heirs and
+successors. We intend this dedication to be an overt act of
+relinquishment in perpetuity of all present and future rights to this
+software under copyright law.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+OTHER DEALINGS IN THE SOFTWARE.
+
+For more information, please refer to <https://unlicense.org>

README.md

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+N64Swap
+=======
+Swaps .n64, .v64 and .z64 roms. Written in Python 3. You must install `numpy` via e.g. pip. Code is kinda messy.
+
+## Usage
+```
+n64swap.py [-h] input output
+```
+
+## Technical information
+`.z64` is the correct format and should be used. This handy table shows the [difference](https://old.reddit.com/r/emulation/comments/7hrvzp/the_three_different_n64_rom_formats_explained_for/):
+
+| ROM format | Type          | First 4 bytes | Game Title in ROM  |
+|------------|---------------|---------------|--------------------|
+| .z64       | Big Endian    | 80 37 12 40   | `SUPER MARIO 64  ` |
+| .v64       | Byteswapped   | 37 80 40 12   | `USEP RAMIR O64  ` |
+| .n64       | Little Endian | 40 12 37 80   | `EPUSAM R OIR  46` |
+
+(Note that there are two spaces after both "64", they don't seem to show up here.)

n64swap.py

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+#!/usr/bin/env python3
+import os
+from argparse import ArgumentParser
+
+import numpy
+
+valid_ext = [".n64", ".v64", ".z64"]
+parser = ArgumentParser()
+parser.add_argument('input', type=str, help="Input File")
+parser.add_argument('output', type=str, help="Output File")
+arguments = parser.parse_args()
+
+
+def read_in_chunks(file_object, chunk_size=1024):
+    """Lazy function (generator) to read a file piece by piece.
+    Default chunk size: 1k."""
+    while True:
+        data = file_object.read(chunk_size)
+        if not data:
+            break
+        yield data
+
+
+def get_rom_format(rom_header):
+    if rom_header == b"\x40\x12\x37\x80":
+        return ".n64"
+    elif rom_header == b"\x80\x37\x12\x40":
+        return ".z64"
+    elif rom_header == b"\x37\x80\x40\x12":
+        return ".v64"
+    else:
+        return None
+
+
+def swap_bytes(b):
+    chunk_bytearray = bytearray(b)
+    byteswapped = bytearray(len(b))
+    byteswapped[0::2] = chunk_bytearray[1::2]
+    byteswapped[1::2] = chunk_bytearray[0::2]
+    return byteswapped
+
+
+def main(infile, outfile):
+    # TODO: check if input == output
+
+    output_ext = os.path.splitext(outfile)[1]
+    if output_ext.lower() not in valid_ext:
+        print("Output file must end with .n64, .v64 or .z64")
+        return
+
+    with open(infile, "rb") as rom_file:
+        rom_header = rom_file.read(4)
+        rom_format = get_rom_format(rom_header)
+        if not rom_format:
+            print("Not an N64 rom.")
+            return
+        rom_file.seek(0)
+
+        print("{0} -> {1}".format(rom_format, output_ext))
+        with open(outfile, "wb") as out_file:
+            if rom_format == output_ext:  # Just copy it
+                for chunk in read_in_chunks(rom_file):
+                    out_file.write(chunk)
+
+            if rom_format == ".z64":  # Big Endian
+                if output_ext == ".n64":  # Big Endian -> Little Endian
+                    for chunk in read_in_chunks(rom_file):
+                        out_file.write(numpy.frombuffer(chunk, numpy.float32).byteswap())
+                elif output_ext == ".v64":  # Big Endian -> Byteswapped
+                    for chunk in read_in_chunks(rom_file):
+                        out_file.write(swap_bytes(chunk))
+
+            elif rom_format == ".n64":  # Little Endian
+                if output_ext == ".z64":  # Little Endian -> Big Endian
+                    for chunk in read_in_chunks(rom_file):
+                        out_file.write(numpy.frombuffer(chunk, numpy.float32).byteswap())
+                elif output_ext == ".v64":  # Little Endian -> Big Endian -> Byteswapped
+                    for chunk in read_in_chunks(rom_file):
+                        endian_swapped = numpy.frombuffer(chunk, numpy.float32).byteswap()
+                        out_file.write(swap_bytes(endian_swapped.tobytes()))
+
+            elif rom_format == ".v64":  # Byteswapped
+                if output_ext == ".n64":  # Byteswapped -> Big Endian -> Little Endian
+                    for chunk in read_in_chunks(rom_file):
+                        endian_swapped = numpy.frombuffer(chunk, numpy.float32).byteswap()
+                        out_file.write(swap_bytes(endian_swapped.tobytes()))
+                elif output_ext == ".z64":  # Byteswapped -> Big Endian
+                    for chunk in read_in_chunks(rom_file):
+                        out_file.write(swap_bytes(chunk))
+
+    print("Conversion finished.")
+
+
+if __name__ == "__main__":
+    main(infile=arguments.input, outfile=arguments.output)

requirements.txt

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+numpy