feat(registers): ICODE feature-flags decoder (GET NXP SYSTEM INFO)

Add IcodeFeatureFlags (Register) for the 16-bit ICODE feature word
reported by GET NXP SYSTEM INFO (ICODE 3 Table 113; DNA/SLIX2 report a
subset). Read-only capability decoder — decode a captured word to see
what a tag supports. Fields mirror the existing _FEATURE_* constants
one-to-one (asserted in a test). 3 new tests.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

pm3py/sim/__init__.py

@@ -46,7 +46,7 @@ from pm3py.transponders.hf.iso15693.type5 import NfcType5Tag, ndef_text, ndef_ur
 from pm3py.transponders.hf.iso15693.nxp.nxp_icode import NxpIcodeTag
 from pm3py.transponders.hf.iso15693.nxp.icode_slix import IcodeSlixTag
 from pm3py.transponders.hf.iso15693.nxp.icode_slix2 import IcodeSlix2Tag
-from pm3py.transponders.hf.iso15693.nxp.icode3 import Icode3Tag
+from pm3py.transponders.hf.iso15693.nxp.icode3 import Icode3Tag, IcodeFeatureFlags
 from pm3py.transponders.hf.iso15693.nxp.icode_dna import IcodeDnaTag
 from pm3py.transponders.hf.iso15693.nxp.auth_aes import NxpKeyPrivileges
 from pm3py.transponders.hf.iso15693.nxp.ntag5_platform import (
@@ -115,7 +115,7 @@ __all__ = [
     "Icode3Tag", "IcodeDnaTag",
     "Ntag5PlatformTag", "Ntag5SwitchTag", "Ntag5LinkTag", "Ntag5BoostTag",
     "Ntag5StatusReg", "Ntag5ConfigReg",
-    "NxpKeyPrivileges",
+    "NxpKeyPrivileges", "IcodeFeatureFlags",
     "DesfireTag", "DesfireReader",
     "xEM", "xNT", "xM1", "FlexDF", "NExT", "MagicMifareClassicTag",
     "MutationFuzzer", "GrammarFuzzer",

pm3py/transponders/hf/iso15693/nxp/icode3.py

@@ -16,6 +16,7 @@ import os
 import struct
 
 from pm3py.sim.frame import RFFrame
+from pm3py.transponders.bitfield import BitField, Register
 from .icode_slix2 import IcodeSlix2Tag, PWD_READ, PWD_WRITE
 from .nxp_icode import NXP_MFG
 
@@ -44,6 +45,33 @@ _FEATURE_WRITE_CID = 1 << 14
 _FEATURE_HIGH_DATA_RATES = 1 << 15
 
 
+class IcodeFeatureFlags(Register):
+    """The NXP ICODE feature-flags word reported by GET NXP SYSTEM INFO (ICODE 3 Table 113;
+    ICODE DNA / SLIX2 report a subset). Read-only capability bits — decode a word you captured
+    to see what a tag supports. 16-bit little-endian on the wire, but treated here as one word
+    (bit N is feature flag N)."""
+
+    _width_bits = 16
+    _label = "ICODE feature flags"
+
+    um_pp = BitField(0, doc="user-memory password protection")
+    counter = BitField(1, doc="single-block read counter")
+    eas_id = BitField(2, doc="EAS ID")
+    eas_pp = BitField(3, doc="EAS password protection")
+    afi_pp = BitField(4, doc="AFI password protection")
+    inventory_read_ext = BitField(5, doc="extended INVENTORY READ")
+    eas_ir = BitField(6, doc="EAS in INVENTORY READ")
+    cid = BitField(7, doc="configurable customer ID")
+    originality_sig = BitField(8, doc="ECC originality signature")
+    tagtamper = BitField(9, doc="tag-tamper feature")
+    p_quiet = BitField(10, doc="persistent QUIET state")
+    nfc_mirror = BitField(11, doc="NFC ASCII mirror")
+    privacy = BitField(12, doc="privacy mode")
+    destroy = BitField(13, doc="DESTROY command")
+    write_cid = BitField(14, doc="writeable customer ID")
+    high_data_rates = BitField(15, doc="high data-rate support")
+
+
 class Icode3Tag(IcodeSlix2Tag):
     """ICODE 3 transponder (SL2S3003 / SL2S3003TT).
 

tests/test_bitfield.py

@@ -10,6 +10,7 @@ from pm3py.sim import (
     NtagI2CConfig, NtagI2CSession, NtagI2CPtI2C, NT3H2111, NT3H2211,
     Ntag5StatusReg, Ntag5ConfigReg, Ntag5LinkTag,
     NxpKeyPrivileges, IcodeDnaTag,
+    IcodeFeatureFlags,
 )
 
 
@@ -467,3 +468,26 @@ class TestNxpKeyPrivileges:
         text = repr(NxpKeyPrivileges.build(read=True, destroy=True))
         assert "NXP key privileges" in text
         assert "read" in text and "destroy" in text
+
+
+class TestIcodeFeatureFlags:
+    def test_bits_match_module_constants(self):
+        import pm3py.transponders.hf.iso15693.nxp.icode3 as ic3
+        # every declared field must line up with the _FEATURE_* constant of the same name
+        for name, bf in IcodeFeatureFlags.fields():
+            const = getattr(ic3, f"_FEATURE_{name.upper()}")
+            assert (1 << bf.lo) == const, name
+
+    def test_decode(self):
+        # um_pp(0) + counter(1) + originality_sig(8) + high_data_rates(15)
+        w = (1 << 0) | (1 << 1) | (1 << 8) | (1 << 15)
+        f = IcodeFeatureFlags(w)
+        assert f.um_pp is True and f.counter is True
+        assert f.originality_sig is True and f.high_data_rates is True
+        assert f.privacy is False
+        assert int(f) == w
+
+    def test_repr(self):
+        text = repr(IcodeFeatureFlags(0x0001))
+        assert "ICODE feature flags" in text
+        assert "um_pp" in text