Script to extract 3DS PICA200 shaders from (decrypted) binaries which can then be disassembled with aemstro or nihstro. Should work on anything like .cia .3ds .3dsx... Writes each shader in a .shbin file in the current directory.

extractPicaShaders.py

#!/bin/python3
#https://problemkaputt.de/gbatek-3ds-files-video-shaders-dvlb-and-dvob-format.htm
import sys, mmap, struct as s
magic = b"DVLB"
magicDVLE = b'DVLE'
magicDVLEInt = s.unpack("<I", magicDVLE)[0]
def ph(v):
	print(hex(v))
def readInt(mm, base, idx):
	start = base+idx*4
	return s.unpack("<I", mm[start:start+4])[0]
def isValidDVLB(mm, pos, numDVLEs):
	print("Found a possible DVLB at 0x%x, validating..." % (pos))
	if numDVLEs <= 0:
		return False
	for j in range(numDVLEs):
		DVLEStart = pos + readInt(mm, pos, 2+j)
		if DVLEStart < pos or DVLEStart-pos > 0x4000: #TODO: research this value further, biggest seen: 0x2038 (Art of Balance TOUCH!)
			print("DVLB validation failed: DVLE is at offset = %s" % hex(DVLEStart-pos), file=sys.stderr)
			return False
		#print("DEBUG: Valid DVLE offset %s" % hex(DVLEStart-pos))
		DVLEHeader = readInt(mm, DVLEStart, 0)
		if DVLEHeader != magicDVLEInt:
			print("DVLB validation failed: DVLE has invalid magic", file=sys.stderr)
			return False
		shaderType = mm[DVLEStart+6]
		if shaderType > 1:
			print("DVLB validation failed: DVLE has invalid shaderType %d" % (shaderType), file=sys.stderr)
			return False
	return True

if len(sys.argv) != 2:
	print("You need to pass a binary file to search shaders from", file=sys.stderr)
	sys.exit(1)
filename = '.'.join(sys.argv[1].split('/')[-1].split('.')[0:-1])
with open(sys.argv[1], "rb+") as f:
	mm = mmap.mmap(f.fileno(), 0)
	i=1
	pos = mm.find(magic, 0)
	while(pos != -1):
		numDVLEs=readInt(mm, pos, 1)
		if isValidDVLB(mm, pos, numDVLEs):
			shaderFilename = "%s_shader%d.shbin" % (filename, i)
			print("Valid DVLB %d at 0x%x. Saving to current folder as %s" % (i, pos, shaderFilename))
			lastDVLEStart = pos + readInt(mm, pos, 2+ numDVLEs-1)
			SymTableOff = readInt(mm, lastDVLEStart, 14)
			SymTableSize = readInt(mm, lastDVLEStart, 15)
			endOffset = lastDVLEStart+SymTableOff+SymTableSize
			with open(shaderFilename, "wb") as shaderFile:
				shaderFile.write(mm[pos:endOffset])
			i+=1
			pos = mm.find(magic, endOffset)
		else:
			pos = mm.find(magic, pos+1)
	if i == 1:
		print("No shaders found in %s. The binary may be encrypted" % sys.argv[1], file=sys.stderr)