Links Awakening: Implement New Game (#1334)

Adds Link's Awakening: DX. Fully imports and forks LADXR, with permission - https://github.com/daid/LADXR

worlds/ladx/LADXR/rom.py

@@ -0,0 +1,75 @@
+import binascii
+
+b2h = binascii.hexlify
+h2b = binascii.unhexlify
+
+
+class ROM:
+    def __init__(self, filename):
+        data = open(filename, "rb").read()
+        #assert len(data) == 1024 * 1024
+        self.banks = []
+        for n in range(0x40):
+            self.banks.append(bytearray(data[n*0x4000:(n+1)*0x4000]))
+
+    def patch(self, bank_nr, addr, old, new, *, fill_nop=False):
+        new = h2b(new)
+        bank = self.banks[bank_nr]
+        if old is not None:
+            if isinstance(old, int):
+                old = bank[addr:old]
+            else:
+                old = h2b(old)
+            if fill_nop:
+                assert len(old) >= len(new), "Length mismatch: %d != %d (%s != %s)" % (len(old), len(new), b2h(old), b2h(new))
+                new += b'\x00' * (len(old) - len(new))
+            else:
+                assert len(old) == len(new), "Length mismatch: %d != %d (%s != %s)" % (len(old), len(new), b2h(old), b2h(new))
+            assert addr >= 0 and addr + len(old) <= 16*1024
+            if bank[addr:addr+len(old)] != old:
+                if bank[addr:addr + len(old)] == new:
+                    # Patch is already applied.
+                    return
+                loc = bank.find(old)
+                while loc > -1:
+                    print("Possible at:", hex(loc))
+                    loc = bank.find(old, loc+1)
+                assert False, "Patch mismatch:\n%s !=\n%s at 0x%04x" % (b2h(bank[addr:addr+len(old)]), b2h(old), addr)
+        bank[addr:addr+len(new)] = new
+        assert len(bank) == 0x4000
+
+    def fixHeader(self, *, name=None):
+        if name is not None:
+            name = name.encode("utf-8")
+            name = (name + (b"\x00" * 15))[:15]
+            self.banks[0][0x134:0x143] = name
+
+        checksum = 0
+        for c in self.banks[0][0x134:0x14D]:
+            checksum -= c + 1
+        self.banks[0][0x14D] = checksum & 0xFF
+
+        # zero out the checksum before calculating it.
+        self.banks[0][0x14E] = 0
+        self.banks[0][0x14F] = 0
+        checksum = 0
+        for bank in self.banks:
+            checksum = (checksum + sum(bank)) & 0xFFFF
+        self.banks[0][0x14E] = checksum >> 8
+        self.banks[0][0x14F] = checksum & 0xFF
+
+    def save(self, file, *, name=None):
+        # don't pass the name to fixHeader
+        self.fixHeader()
+        if isinstance(file, str):
+            f = open(file, "wb")
+            for bank in self.banks:
+                f.write(bank)
+            f.close()
+            print("Saved:", file)
+        else:
+            for bank in self.banks:
+                file.write(bank)
+
+    def readHexSeed(self):
+        return self.banks[0x3E][0x2F00:0x2F10].hex().upper()