Add an example for using constant renderers to render unusual floating point constant encodings directly in the decompilation

1 files changed, 42 insertions, 0 deletions

diff --git a/python/examples/bid64_constant.py b/python/examples/bid64_constant.py
new file mode 100644
index 00000000..d5f49ccd
--- /dev/null
+++ b/python/examples/bid64_constant.py
@@ -0,0 +1,42 @@
+# This plugin renders 64-bit binary integer decimal floating point constants directly in the
+# decompilation. See the sample binary at `examples/bid64_constant/sample_binary` for an
+# example of a binary that uses this unusual format.
+
+from binaryninja import (ConstantRenderer, InstructionTextToken, InstructionTextTokenType, IntegerType)
+from decimal import Decimal
+
+
+class Bid64ConstantRenderer(ConstantRenderer):
+    renderer_name = "bid64_constant"
+
+    def render_constant(self, instr, type, val, tokens, settings, precedence):
+        # Typedefs have the final type, so make sure it is a 64 bit integer. The registered name
+        # should be the typedef "BID_UINT64".
+        if not isinstance(type, IntegerType):
+            return False
+        if type.width != 8:
+            return False
+        if type.registered_name is None or type.registered_name.name != 'BID_UINT64':
+            return False
+
+        sign = (val & (1 << 63)) != 0
+        raw_exponent = (val >> 53) & 0x3ff
+        if raw_exponent >= 0x300:
+            # Don't try and render NaN or infinity
+            return False
+
+        bias = 398
+        exponent = raw_exponent - bias
+        magnitude = val & ((1 << 53) - 1)
+
+        if magnitude == 0:
+            exponent = 0
+
+        value = Decimal(magnitude) * Decimal(10.0) ** Decimal(exponent)
+        if sign:
+            value = -value
+        tokens.append(InstructionTextToken(InstructionTextTokenType.FloatingPointToken, str(value) + "_bid"))
+        return True
+
+
+Bid64ConstantRenderer().register()