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fixbaserom.py: Add support to v64 format and improve performance (#629)

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* Add byte swap for v64 files

Signed-off-by: angie <angheloalf95@gmail.com>

* Reduce `len` function calls

Signed-off-by: angie <angheloalf95@gmail.com>

* Optimze a bit the byte-swapped v64 format

Signed-off-by: angie <angheloalf95@gmail.com>

* Strip the overdump before doing the byte-swap

The previous way wasted time by byte-swapping data that would be discarded anyway.

Signed-off-by: angie <angheloalf95@gmail.com>

* Swap twice the bytes per cycle to improve performance

Signed-off-by: angie <angheloalf95@gmail.com>

* Read and write 16 bytes at a time and specify explicit endianness

Reading more bytes per cycle allow to speed up the swapping proccess

Signed-off-by: angie <angheloalf95@gmail.com>

* Add v64 compatibility in the Readme

Signed-off-by: angie <angheloalf95@gmail.com>

* Read whole file as little endian and write it as big endian without the loop

Signed-off-by: angie <angheloalf95@gmail.com>
This commit is contained in:
Anghelo Carvajal 2021-01-14 17:14:33 -03:00 committed by GitHub
parent 65e956a272
commit 9c2ad0c60b
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GPG key ID: 4AEE18F83AFDEB23
2 changed files with 41 additions and 31 deletions
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2
README.md
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@ -94,7 +94,7 @@ git clone https://github.com/zeldaret/oot.git
#### 4. Prepare a base ROM
Copy over your copy of the Master Quest (Debug) ROM inside the root of this new project directory.
Rename the file to "baserom_original.z64" or "baserom_original.n64", depending on the original extension.
Rename the file to "baserom_original.z64", "baserom_original.n64" or "baserom_original.v64", depending on the original extension.
#### 5. Setup the ROM and build process

68
fixbaserom.py
View file

@ -22,44 +22,54 @@ if path.exists("baserom_original.z64"):
romFileName = "baserom_original.z64"
elif path.exists("baserom_original.n64"):
romFileName = "baserom_original.n64"
elif path.exists("baserom_original.v64"):
romFileName = "baserom_original.v64"
else:
print("Error: Could not find baserom_original.z64/baserom_original.n64/baserom_original.v64.")
sys.exit(1)
# Read in the original ROM
if romFileName != "":
print("File '" + romFileName + "' found.")
with open(romFileName, mode="rb") as file:
fileContent = bytearray(file.read())
# Check if ROM needs to be byte swapped
if fileContent[0] == 0x40:
# Byte Swap ROM
# TODO: This is pretty slow at the moment. Look into optimizing it later...
print("ROM needs to be byte swapped...")
i = 0
while i < len(fileContent):
tmp = struct.unpack_from("BBBB", fileContent, i)
struct.pack_into("BBBB", fileContent, i + 0, tmp[3], tmp[2], tmp[1], tmp[0])
i += 4
perc = float(i) / float(len(fileContent))
if i % (1024 * 1024 * 4) == 0:
print(str(perc * 100) + "%")
print("Byte swapping done.")
else:
print("Error: Could not find baserom_original.z64/baserom_original.n64.")
sys.exit(1)
print("File '" + romFileName + "' found.")
with open(romFileName, mode="rb") as file:
fileContent = bytearray(file.read())
# Strip the overdump
print("Stripping overdump...")
strippedContent = list(fileContent[0:0x3600000])
fileContent = fileContent[0:0x3600000]
fileContentLen = len(fileContent)
# Check if ROM needs to be byte/word swapped
# Little-endian
if fileContent[0] == 0x40:
# Word Swap ROM
print("ROM needs to be word swapped...")
words = str(int(fileContentLen/4))
little_byte_format = "<" + words + "I"
big_byte_format = ">" + words + "I"
tmp = struct.unpack_from(little_byte_format, fileContent, 0)
struct.pack_into(big_byte_format, fileContent, 0, *tmp)
print("Word swapping done.")
# Byte-swapped
elif fileContent[0] == 0x37:
# Byte Swap ROM
print("ROM needs to be byte swapped...")
halfwords = str(int(fileContentLen/2))
little_byte_format = "<" + halfwords + "H"
big_byte_format = ">" + halfwords + "H"
tmp = struct.unpack_from(little_byte_format, fileContent, 0)
struct.pack_into(big_byte_format, fileContent, 0, *tmp)
print("Byte swapping done.")
# Patch the header
print("Patching header...")
strippedContent[0x3E] = 0x50
fileContent[0x3E] = 0x50
# Check to see if the ROM is a "vanilla" Debug ROM
str_hash = get_str_hash(bytearray(strippedContent))
str_hash = get_str_hash(bytearray(fileContent))
if str_hash != "f0b7f35375f9cc8ca1b2d59d78e35405":
print("Error: Expected a hash of f0b7f35375f9cc8ca1b2d59d78e35405 but got " + str_hash + ". " +
"The baserom has probably been tampered, find a new one")
@ -68,6 +78,6 @@ if str_hash != "f0b7f35375f9cc8ca1b2d59d78e35405":
# Write out our new ROM
print("Writing new ROM 'baserom.z64'.")
with open("baserom.z64", mode="wb") as file:
file.write(bytes(strippedContent))
file.write(bytes(fileContent))
print("Done!")