From 3449e28b439e8d529ff41e466319292339757fe7 Mon Sep 17 00:00:00 2001
From: Johannes Stoelp <johannes.stoelp@gmail.com>
Date: Mon, 30 Oct 2023 23:02:37 +0100
Subject: lt_bus: factor our computation of abs mmap address

---
 src/models/lt_bus.h | 62 +++++++++++++++++++++++++++--------------------------
 1 file changed, 32 insertions(+), 30 deletions(-)

(limited to 'src/models/lt_bus.h')

diff --git a/src/models/lt_bus.h b/src/models/lt_bus.h
index a8391f8..9b16ab9 100644
--- a/src/models/lt_bus.h
+++ b/src/models/lt_bus.h
@@ -104,22 +104,12 @@ class lt_bus : public sc_core::sc_module {
         continue;
       }
 
-      // Compute absolute start address.
-      const sc_dt::uint64 abs_start = map.addr.start + start;
-      assert(abs_start <= map.addr.end);
-
-      // Compute absolute end address. Limit if mapping range exceeded.
-      const auto comp_abs_end = [&map](sc_dt::uint64 abs_end) -> sc_dt::uint64 {
-        if (abs_end > map.addr.end /* exceeds mapping */ ||
-            abs_end < map.addr.start /* wraps around */) {
-          return map.addr.end;
-        }
-        return abs_end;
-      };
-      const sc_dt::uint64 abs_end = comp_abs_end(map.addr.start + end);
+      // Compute absolute start/end address based on memory map.
+      const range abs_addr =
+          compute_abs_mmap_address(range{start, end}, map.addr);
 
       for (auto& sock : m_initiators) {
-        (*sock)->invalidate_direct_mem_ptr(abs_start, abs_end);
+        (*sock)->invalidate_direct_mem_ptr(abs_addr.start, abs_addr.end);
       }
     }
   }
@@ -155,23 +145,14 @@ class lt_bus : public sc_core::sc_module {
         return false;
       }
 
-      // Compute absolute start address.
-      const sc_dt::uint64 abs_start = r.start + dmi.get_start_address();
-      assert(abs_start < r.end);
+      // Compute absolute start/end address based on memory map.
+      const range abs_addr = compute_abs_mmap_address(
+          range{dmi.get_start_address(), dmi.get_end_address()},
+          range{r.start, r.end});
 
-      // Compute absolute end address. Limit if mapping range exceeded.
-      const auto comp_abs_end = [&r](sc_dt::uint64 abs_end) -> sc_dt::uint64 {
-        if (abs_end > r.end /* exceeds mapping */ ||
-            abs_end < r.start /* wraps around */) {
-          return r.end;
-        }
-        return abs_end;
-      };
-      const sc_dt::uint64 abs_end =
-          comp_abs_end(r.start + dmi.get_end_address());
-
-      dmi.set_start_address(abs_start);
-      dmi.set_end_address(abs_end);
+      // Update dmi payload with absolute addresses.
+      dmi.set_start_address(abs_addr.start);
+      dmi.set_end_address(abs_addr.end);
 
       return true;
     }
@@ -218,6 +199,27 @@ class lt_bus : public sc_core::sc_module {
     return decode(range{start, end});
   }
 
+  // -- COMPUTE ABSOLUTE MEMORY MAP ADDRESS ------------------------------------
+
+  static range compute_abs_mmap_address(range rel, range map) {
+    // Compute absolute start address.
+    const sc_dt::uint64 abs_start = map.start + rel.start;
+    // Start address must be in bounds of the memory map mapping.
+    assert(abs_start <= map.end);
+
+    // Compute absolute end address. Limit by memory map if range exceeded.
+    const auto comp_abs_end = [&map](sc_dt::uint64 abs_end) -> sc_dt::uint64 {
+      if (abs_end > map.end /* exceeds mapping */ ||
+          abs_end < map.start /* wraps around */) {
+        return map.end;
+      }
+      return abs_end;
+    };
+    const sc_dt::uint64 abs_end = comp_abs_end(map.start + rel.end);
+
+    return range{abs_start, abs_end};
+  }
+
   // -- SC_MODULE CALLBACKS ----------------------------------------------------
 
   virtual void start_of_simulation() override {
-- 
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