chore: Get display EDID patching working

libunreal/edid.py

@@ -1,4 +1,7 @@
+from loguru import logger
+
 import dataclasses
+import uuid
 
 @dataclasses.dataclass
 class EvdiDisplaySpec:
@@ -6,3 +9,76 @@ class EvdiDisplaySpec:
     max_width: int
     max_height: int
     max_refresh_rate: int
+    linux_drm_card: str
+    linux_drm_connector: str
+
+calculated_msft_payload_size = 22+4
+
+def calculate_checksum(block):
+    checksum = (-sum(block[:-1])) & 0xFF
+    return checksum
+
+def patch_edid_to_be_specialized(edid_data: bytes | bytearray) -> bytes | bytearray:
+    mutable_edid = bytearray(edid_data)
+    is_enhanced_mode = len(edid_data) > 128
+
+    found_extension_base = 0
+    extension_base_existed = False
+
+    if is_enhanced_mode:
+        for i in range(128, len(edid_data), 128):
+            if edid_data[i] == 0x02:
+                logger.warning("Detected existing ANSI CTA data section. Patching in place but untested! Please report any issues you discover")
+
+                if edid_data[i+1] != 0x03:
+                    logger.warning("Incompatible version detected for ANSI CTA data section in EDID")
+
+                found_extension_base = i
+                extension_base_existed = True
+
+        if found_extension_base == 0:
+            found_extension_base = len(edid_data)
+            mutable_edid.extend([0]*128)
+    else:
+        mutable_edid.extend([0]*128)
+        found_extension_base = 128
+
+    generated_uuid = uuid.uuid4()
+
+    mutable_edid[found_extension_base] = 0x02
+    mutable_edid[found_extension_base+1] = 0x03
+
+    if extension_base_existed and mutable_edid[found_extension_base+2] != calculated_msft_payload_size and mutable_edid[found_extension_base+2] != 0:
+        # We try our best to move our data into place
+        current_base = mutable_edid[found_extension_base+2]
+        mutable_edid[found_extension_base+2] = calculated_msft_payload_size+1
+
+        mutable_edid[found_extension_base+4:found_extension_base+current_base-1] = [0]*(current_base-1)
+        mutable_edid[found_extension_base+calculated_msft_payload_size:found_extension_base+127] = mutable_edid[found_extension_base+current_base:found_extension_base+127]
+    else:
+        mutable_edid[found_extension_base+2] = calculated_msft_payload_size
+
+    if not extension_base_existed:
+        mutable_edid[126] += 1
+        mutable_edid[127] = calculate_checksum(mutable_edid[:128])
+
+        mutable_edid[found_extension_base+3] = 0 # We don't know any of these properties
+
+    # Implemented using https://learn.microsoft.com/en-us/windows-hardware/drivers/display/specialized-monitors-edid-extension
+    # VST & Length
+    mutable_edid[found_extension_base+4] = 0x3 << 5 | 0x15 # 0x3: vendor specific tag; 0x15: length
+    # Assigned IEEE OUI
+    mutable_edid[found_extension_base+5] = 0x5C
+    mutable_edid[found_extension_base+6] = 0x12
+    mutable_edid[found_extension_base+7] = 0xCA
+    # Actual data
+    mutable_edid[found_extension_base+8] = 0x2 # Using version 0x2 for better compatibility
+    mutable_edid[found_extension_base+9] = 0x7 # Using VR tag for better compatibility even though it probably doesn't matter
+    mutable_edid[found_extension_base+10:found_extension_base+10+16] = generated_uuid.bytes
+
+    mutable_edid[found_extension_base+127] = calculate_checksum(mutable_edid[found_extension_base:found_extension_base+127])
+
+    if isinstance(edid_data, bytes):
+        return bytes(mutable_edid)
+    else:
+        return mutable_edid