Adding compress/decompress script for use with gfx
This commit is contained in:
codemann8
135
menu/compress.py
Normal file
135
menu/compress.py
Normal file
@@ -0,0 +1,135 @@
|
||||
import sys
|
||||
import os
|
||||
|
||||
# Compression function reverse-engineered from ALTTP's decompression routine at $00E7DE
|
||||
def compress(data):
|
||||
out = bytearray()
|
||||
i = 0
|
||||
|
||||
while i < len(data):
|
||||
# Check for repeating byte pattern
|
||||
if i + 1 < len(data) and data[i] == data[i + 1]:
|
||||
length = 2
|
||||
while i + length < len(data) and data[i] == data[i + length] and length < 32:
|
||||
length += 1
|
||||
# Repeating byte: 0x20-0x3F
|
||||
out.append(0x20 | (length - 1))
|
||||
out.append(data[i])
|
||||
i += length
|
||||
continue
|
||||
|
||||
# Check for incremental byte pattern
|
||||
if i + 2 < len(data) and data[i + 1] == data[i] + 1 and data[i + 2] == data[i] + 2:
|
||||
length = 3
|
||||
while i + length < len(data) and data[i + length] == data[i] + length and length < 32:
|
||||
length += 1
|
||||
# Incremental: 0x60-0x7F
|
||||
out.append(0x60 | (length - 1))
|
||||
out.append(data[i])
|
||||
i += length
|
||||
continue
|
||||
|
||||
# Check for repeating word pattern (alternating two bytes)
|
||||
if i + 3 < len(data):
|
||||
# Check if we have an alternating pattern: A B A B...
|
||||
byte_a = data[i]
|
||||
byte_b = data[i + 1]
|
||||
length = 2
|
||||
while i + length < len(data) and length < 32:
|
||||
if length % 2 == 0:
|
||||
if data[i + length] != byte_a:
|
||||
break
|
||||
else:
|
||||
if data[i + length] != byte_b:
|
||||
break
|
||||
length += 1
|
||||
|
||||
if length >= 4: # Need at least 4 bytes (2 alternations) to make it worthwhile
|
||||
# Repeating word: 0x40-0x5F
|
||||
out.append(0x40 | (length - 1))
|
||||
out.append(byte_a)
|
||||
out.append(byte_b)
|
||||
i += length
|
||||
continue
|
||||
|
||||
# Check for copy from past (LZ with absolute offset)
|
||||
best_len = 0
|
||||
best_off = 0
|
||||
search_start = max(0, i - 65536) # Can reference anywhere in output
|
||||
for j in range(search_start, i):
|
||||
length = 0
|
||||
while i + length < len(data) and data[j + length] == data[i + length] and length < 1024:
|
||||
length += 1
|
||||
if length >= 2 and length > best_len:
|
||||
best_len = length
|
||||
best_off = j # Absolute offset, not relative!
|
||||
|
||||
if best_len >= 2:
|
||||
# Copy from past: 0x80-0xDF or 0xE0-0xFE (extended)
|
||||
# Offset is ABSOLUTE position in the output buffer
|
||||
if best_len <= 32:
|
||||
# Standard copy: 0x80-0xDF (5 bits for length-1, 16 bits for absolute offset)
|
||||
out.append(0x80 | ((best_len - 1) & 0x1F))
|
||||
out.append(best_off & 0xFF)
|
||||
out.append((best_off >> 8) & 0xFF)
|
||||
else:
|
||||
# Extended copy: 0xE0-0xFE
|
||||
if best_len > 1024:
|
||||
best_len = 1024
|
||||
# Command byte: 111LLLLL where L is length bits
|
||||
cmd = 0xE0 | (((best_len - 1) >> 8) & 0x1F)
|
||||
out.append(cmd)
|
||||
out.append((best_len - 1) & 0xFF)
|
||||
out.append(best_off & 0xFF)
|
||||
out.append((best_off >> 8) & 0xFF)
|
||||
i += best_len
|
||||
continue
|
||||
|
||||
# Raw copy (no pattern found)
|
||||
size = 1
|
||||
while size < 32 and i + size < len(data):
|
||||
# Don't extend raw copy if we find a better pattern ahead
|
||||
if i + size + 1 < len(data) and data[i + size] == data[i + size + 1]:
|
||||
break
|
||||
if i + size + 2 < len(data) and data[i + size + 1] == data[i + size] + 1:
|
||||
break
|
||||
# Check LZ
|
||||
found_lz = False
|
||||
for j in range(max(0, i + size - 2048), i + size):
|
||||
if i + size + 1 < len(data) and data[j] == data[i + size] and data[j + 1] == data[i + size + 1]:
|
||||
found_lz = True
|
||||
break
|
||||
if found_lz:
|
||||
break
|
||||
size += 1
|
||||
|
||||
# Raw copy: 0x00-0x1F
|
||||
out.append(size - 1)
|
||||
out.extend(data[i:i + size])
|
||||
i += size
|
||||
|
||||
# End marker
|
||||
out.append(0xFF)
|
||||
return out
|
||||
|
||||
if __name__ == '__main__':
|
||||
if len(sys.argv) != 3:
|
||||
print("Usage: python compress.py <input_file> <output_file>")
|
||||
sys.exit(1)
|
||||
|
||||
input_file_path = sys.argv[1]
|
||||
output_file_path = sys.argv[2]
|
||||
|
||||
if not os.path.exists(input_file_path):
|
||||
print(f"Error: Input file not found at {input_file_path}")
|
||||
sys.exit(1)
|
||||
|
||||
with open(input_file_path, 'rb') as f:
|
||||
input_data = f.read()
|
||||
|
||||
compressed_data = compress(input_data)
|
||||
|
||||
with open(output_file_path, 'wb') as f:
|
||||
f.write(compressed_data)
|
||||
|
||||
print(f"Successfully compressed '{input_file_path}' to '{output_file_path}'")
|
||||
112
menu/decompress.py
Normal file
112
menu/decompress.py
Normal file
@@ -0,0 +1,112 @@
|
||||
import sys
|
||||
|
||||
def decompress(compressed_data):
|
||||
out = bytearray()
|
||||
i = 0
|
||||
|
||||
while i < len(compressed_data):
|
||||
cmd = compressed_data[i]
|
||||
|
||||
if cmd == 0xFF:
|
||||
# End marker
|
||||
break
|
||||
|
||||
i += 1
|
||||
|
||||
# Decode based on top 3 bits
|
||||
top_bits = cmd & 0xE0
|
||||
|
||||
if cmd < 0xE0:
|
||||
# Standard commands
|
||||
length = (cmd & 0x1F) + 1
|
||||
|
||||
if top_bits == 0x00:
|
||||
# Raw copy
|
||||
out.extend(compressed_data[i:i+length])
|
||||
i += length
|
||||
elif top_bits == 0x20:
|
||||
# Repeating byte
|
||||
byte_val = compressed_data[i]
|
||||
out.extend([byte_val] * length)
|
||||
i += 1
|
||||
elif top_bits == 0x40:
|
||||
# Repeating word - alternates between two bytes
|
||||
byte_a = compressed_data[i]
|
||||
byte_b = compressed_data[i+1]
|
||||
for j in range(length):
|
||||
if j % 2 == 0:
|
||||
out.append(byte_a)
|
||||
else:
|
||||
out.append(byte_b)
|
||||
i += 2
|
||||
elif top_bits == 0x60:
|
||||
# Incremental
|
||||
start_val = compressed_data[i]
|
||||
for j in range(length):
|
||||
out.append((start_val + j) & 0xFF)
|
||||
i += 1
|
||||
elif top_bits >= 0x80:
|
||||
# Copy from past (absolute offset)
|
||||
offset = compressed_data[i] | (compressed_data[i+1] << 8)
|
||||
for j in range(length):
|
||||
out.append(out[offset + j])
|
||||
i += 2
|
||||
else:
|
||||
# Extended command (0xE0-0xFE)
|
||||
# Command type from bits 5-7 (after shifting)
|
||||
cmd_type = ((cmd << 3) & 0xE0)
|
||||
# Length from bits 0-1 of command (high) + next byte (low)
|
||||
length_high = cmd & 0x03
|
||||
length_low = compressed_data[i]
|
||||
length = (length_high << 8) | length_low
|
||||
length += 1
|
||||
i += 1
|
||||
|
||||
if cmd_type == 0x00:
|
||||
# Extended raw copy
|
||||
out.extend(compressed_data[i:i+length])
|
||||
i += length
|
||||
elif cmd_type == 0x20:
|
||||
# Extended repeating byte
|
||||
byte_val = compressed_data[i]
|
||||
out.extend([byte_val] * length)
|
||||
i += 1
|
||||
elif cmd_type == 0x40:
|
||||
# Extended repeating word - alternates between two bytes
|
||||
byte_a = compressed_data[i]
|
||||
byte_b = compressed_data[i+1]
|
||||
for j in range(length):
|
||||
if j % 2 == 0:
|
||||
out.append(byte_a)
|
||||
else:
|
||||
out.append(byte_b)
|
||||
i += 2
|
||||
elif cmd_type == 0x60:
|
||||
# Extended incremental
|
||||
start_val = compressed_data[i]
|
||||
for j in range(length):
|
||||
out.append((start_val + j) & 0xFF)
|
||||
i += 1
|
||||
elif cmd_type >= 0x80:
|
||||
# Extended copy from past
|
||||
offset = compressed_data[i] | (compressed_data[i+1] << 8)
|
||||
for j in range(length):
|
||||
out.append(out[offset + j])
|
||||
i += 2
|
||||
|
||||
return out
|
||||
|
||||
if __name__ == '__main__':
|
||||
if len(sys.argv) != 3:
|
||||
print("Usage: python decompress.py <input_file> <output_file>")
|
||||
sys.exit(1)
|
||||
|
||||
with open(sys.argv[1], 'rb') as f:
|
||||
compressed = f.read()
|
||||
|
||||
decompressed = decompress(compressed)
|
||||
|
||||
with open(sys.argv[2], 'wb') as f:
|
||||
f.write(decompressed)
|
||||
|
||||
print(f"Decompressed {len(compressed)} bytes to {len(decompressed)} bytes")
|
||||
Reference in New Issue
Block a user