new mpeg transport protocol

construct3_protocols/mpegts.py

@@ -0,0 +1,48 @@
+from construct3 import *
+'''
+transport_packet(){
+ sync_byte  8 bslbf
+ transport_error_indicator 1 bslbf
+ payload_unit_start_indicator 1 bslbf
+ transport_priority 1 bslbf
+ PID  13 uimsbf
+ transport_scrambling_control 2 bslbf
+ adaptation_field_control 2 bslbf
+ continuity_counter 4 uimsbf
+ if(adaptation_field_control == '10' || adaptation_field_control == '11'){
+  adaptation_field()
+ }
+ if(adaptation_field_control == '01' || adaptation_field_control == '11') {
+  for (i = 0; i < N; i++){
+   data_byte 8 bslbf
+    }
+ }
+}
+'''
+transport_packet = Struct(
+    "sync_byte" / uint8,
+    Embedded(BitStruct(
+        "transport_error_indicator" / flag,
+        "payload_unit_start_indicator" / flag,
+        "transport_priority" / flag,
+        "PID" / Bits(13),
+        "transport_scrambling_control" / Bits(2),
+        "adaptation_field_exist" / flag,
+        "payload_exist" / flag,
+        "continuity_counter" / Bits(4),
+        )
+    ),
+    #'''
+    #If(lambda ctx: ctx.adaptation_field_exist,
+    #
+    #),
+    #If(lambda ctx: ctx.payload_exist,
+    #
+    #),
+    #'''
+)
+
+if __name__ == "__main__":
+    import binascii
+    print transport_packet.unpack(binascii.unhexlify("47666666"))
+