From 13bb78203cac7d3a582da55e004c84104ff214dd Mon Sep 17 00:00:00 2001
From: Vegard Storheil Eriksen <zyp@jvnv.net>
Date: Thu, 21 Jan 2021 21:48:58 +0100
Subject: mmio: Add mmio_ptr template.

---
 gdb_plugins/mmio.py | 67 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 mmio/mmio.h         | 29 +++++++++++++++++++++++
 2 files changed, 96 insertions(+)
 create mode 100644 gdb_plugins/mmio.py
 create mode 100644 mmio/mmio.h

diff --git a/gdb_plugins/mmio.py b/gdb_plugins/mmio.py
new file mode 100644
index 0000000..25ebcc3
--- /dev/null
+++ b/gdb_plugins/mmio.py
@@ -0,0 +1,67 @@
+import gdb.xmethod
+
+class RefWorker(gdb.xmethod.XMethodWorker):
+    def __init__(self, result_type):
+        self.result_type = result_type
+
+    def get_arg_types(self):
+        return None
+
+    def get_result_type(self, obj):
+        return self.result_type.reference()
+ 
+    def __call__(self, obj):
+        return obj['p'].cast(self.result_type.pointer()).dereference()
+
+class PtrWorker(gdb.xmethod.XMethodWorker):
+    def __init__(self, result_type):
+        self.result_type = result_type
+
+    def get_arg_types(self):
+        return None
+
+    def get_result_type(self, obj):
+        return self.result_type.pointer()
+ 
+    def __call__(self, obj):
+        return obj['p'].cast(self.result_type.pointer())
+
+class SubscriptWorker(gdb.xmethod.XMethodWorker):
+    def __init__(self, result_type):
+        self.result_type = result_type
+
+    def get_arg_types(self):
+        return [gdb.lookup_type('std::size_t')]
+
+    def get_result_type(self, obj, idx):
+        return self.result_type.reference()
+ 
+    def __call__(self, obj, idx):
+        return obj['p'].cast(self.result_type.pointer())[idx]
+
+class Method(gdb.xmethod.XMethod):
+    def __init__(self, name, worker):
+        gdb.xmethod.XMethod.__init__(self, name)
+        self.worker = worker
+ 
+class Matcher(gdb.xmethod.XMethodMatcher):
+    def __init__(self):
+        gdb.xmethod.XMethodMatcher.__init__(self, 'mmio_ptr matcher')
+
+        self.methods = [
+            Method('operator*', RefWorker),
+            Method('operator->', PtrWorker),
+            Method('operator[]', SubscriptWorker),
+        ]
+ 
+    def match(self, class_type, method_name):
+        if not class_type.name.startswith('mmio_ptr<'):
+            return
+            
+        ptr_type = class_type.template_argument(0)
+
+        for method in self.methods:
+            if method.enabled and method.name == method_name:
+                return method.worker(ptr_type)
+
+gdb.xmethod.register_xmethod_matcher(None, Matcher(), replace = True)
diff --git a/mmio/mmio.h b/mmio/mmio.h
new file mode 100644
index 0000000..a756c8f
--- /dev/null
+++ b/mmio/mmio.h
@@ -0,0 +1,29 @@
+#pragma once
+
+#include <cstdint>
+
+template <typename T>
+class mmio_ptr {
+    private:
+        const uintptr_t p;
+
+    protected:
+        T* ptr() const {
+            return reinterpret_cast<T*>(p);
+        }
+
+    public:
+        constexpr mmio_ptr(uintptr_t p) : p(p) {}
+
+        T* operator->() const {
+            return ptr();
+        }
+
+        T& operator*() const {
+            return *ptr();
+        }
+
+        T& operator[](std::size_t idx) const {
+            return ptr()[idx];
+        }
+};
-- 
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