From 5eabf145c2d5339bf6576dc54b92e78a621e1a92 Mon Sep 17 00:00:00 2001
From: Nav <nav@navnav.me>
Date: Thu, 2 Jun 2022 22:24:37 +0100
Subject: [PATCH] Erasing XMEGA application section upon entering programming
 mode

---
 .../VendorSpecific/EDBG/AVR/Avr8Generic.hpp   |  8 +++++
 .../CommandFrames/AVR8Generic/EraseMemory.hpp | 31 +++++++++++++++++++
 .../EDBG/AVR/EdbgAvr8Interface.cpp            | 18 +++++++++++
 .../EDBG/AVR/EdbgAvr8Interface.hpp            |  7 +++++
 4 files changed, 64 insertions(+)
 create mode 100644 src/DebugToolDrivers/Protocols/CMSIS-DAP/VendorSpecific/EDBG/AVR/CommandFrames/AVR8Generic/EraseMemory.hpp

diff --git a/src/DebugToolDrivers/Protocols/CMSIS-DAP/VendorSpecific/EDBG/AVR/Avr8Generic.hpp b/src/DebugToolDrivers/Protocols/CMSIS-DAP/VendorSpecific/EDBG/AVR/Avr8Generic.hpp
index f3b110b8..4401346e 100644
--- a/src/DebugToolDrivers/Protocols/CMSIS-DAP/VendorSpecific/EDBG/AVR/Avr8Generic.hpp
+++ b/src/DebugToolDrivers/Protocols/CMSIS-DAP/VendorSpecific/EDBG/AVR/Avr8Generic.hpp
@@ -179,4 +179,12 @@ namespace Bloom::DebugToolDrivers::Protocols::CmsisDap::Edbg::Avr
     inline bool operator == (Avr8ResponseId id, unsigned char rawId) {
         return rawId == id;
     }
+
+    enum class Avr8EraseMemoryMode: unsigned char
+    {
+        CHIP = 0x00,
+        APPLICATION_SECTION = 0x01,
+        BOOT_SECTION = 0x02,
+        EEPROM = 0x03,
+    };
 }
diff --git a/src/DebugToolDrivers/Protocols/CMSIS-DAP/VendorSpecific/EDBG/AVR/CommandFrames/AVR8Generic/EraseMemory.hpp b/src/DebugToolDrivers/Protocols/CMSIS-DAP/VendorSpecific/EDBG/AVR/CommandFrames/AVR8Generic/EraseMemory.hpp
new file mode 100644
index 00000000..3da4676a
--- /dev/null
+++ b/src/DebugToolDrivers/Protocols/CMSIS-DAP/VendorSpecific/EDBG/AVR/CommandFrames/AVR8Generic/EraseMemory.hpp
@@ -0,0 +1,31 @@
+#pragma once
+
+#include <cstdint>
+
+#include "Avr8GenericCommandFrame.hpp"
+
+namespace Bloom::DebugToolDrivers::Protocols::CmsisDap::Edbg::Avr::CommandFrames::Avr8Generic
+{
+    class EraseMemory: public Avr8GenericCommandFrame<std::array<unsigned char, 7>>
+    {
+    public:
+        EraseMemory(Avr8EraseMemoryMode mode) {
+            /*
+             * The erase memory command consists of 7 bytes:
+             * 1. Command ID (0x20)
+             * 2. Version (0x00)
+             * 3. Erase mode (see Avr8EraseMemoryMode enum)
+             * 4. Start address (4 bytes) - this is just hardcoded to 0x00000000 for now.
+             */
+            this->payload = {
+                0x20,
+                0x00,
+                static_cast<unsigned char>(mode),
+                0x00,
+                0x00,
+                0x00,
+                0x00,
+            };
+        }
+    };
+}
diff --git a/src/DebugToolDrivers/Protocols/CMSIS-DAP/VendorSpecific/EDBG/AVR/EdbgAvr8Interface.cpp b/src/DebugToolDrivers/Protocols/CMSIS-DAP/VendorSpecific/EDBG/AVR/EdbgAvr8Interface.cpp
index 9b746658..0b42b6c5 100644
--- a/src/DebugToolDrivers/Protocols/CMSIS-DAP/VendorSpecific/EDBG/AVR/EdbgAvr8Interface.cpp
+++ b/src/DebugToolDrivers/Protocols/CMSIS-DAP/VendorSpecific/EDBG/AVR/EdbgAvr8Interface.cpp
@@ -36,6 +36,7 @@
 #include "src/DebugToolDrivers/Protocols/CMSIS-DAP/VendorSpecific/EDBG/AVR/CommandFrames/AVR8Generic/ClearSoftwareBreakpoints.hpp"
 #include "src/DebugToolDrivers/Protocols/CMSIS-DAP/VendorSpecific/EDBG/AVR/CommandFrames/AVR8Generic/EnterProgrammingMode.hpp"
 #include "src/DebugToolDrivers/Protocols/CMSIS-DAP/VendorSpecific/EDBG/AVR/CommandFrames/AVR8Generic/LeaveProgrammingMode.hpp"
+#include "src/DebugToolDrivers/Protocols/CMSIS-DAP/VendorSpecific/EDBG/AVR/CommandFrames/AVR8Generic/EraseMemory.hpp"
 
 // AVR events
 #include "src/DebugToolDrivers/Protocols/CMSIS-DAP/VendorSpecific/EDBG/AVR/Events/AVR8Generic/BreakEvent.hpp"
@@ -691,6 +692,13 @@ namespace Bloom::DebugToolDrivers::Protocols::CmsisDap::Edbg::Avr
         }
 
         this->programmingModeEnabled = true;
+
+        if (this->configVariant == Avr8ConfigVariant::XMEGA) {
+            Logger::warning(
+                "The entire application section of program memory will be erased, in preparation for programming"
+            );
+            this->eraseMemory(Avr8EraseMemoryMode::APPLICATION_SECTION);
+        }
     }
 
     void EdbgAvr8Interface::disableProgrammingMode() {
@@ -1659,6 +1667,16 @@ namespace Bloom::DebugToolDrivers::Protocols::CmsisDap::Edbg::Avr
         if (response.getResponseId() == Avr8ResponseId::FAILED) {
             throw Avr8CommandFailure("AVR8 Write memory command failed", response);
         }
+
+
+    void EdbgAvr8Interface::eraseMemory(Avr8EraseMemoryMode mode) {
+        auto response = this->edbgInterface.sendAvrCommandFrameAndWaitForResponseFrame(
+            CommandFrames::Avr8Generic::EraseMemory(mode)
+        );
+
+        if (response.getResponseId() == Avr8ResponseId::FAILED) {
+            throw Avr8CommandFailure("AVR8 erase memory command failed", response);
+        }
     }
 
     void EdbgAvr8Interface::refreshTargetState() {
diff --git a/src/DebugToolDrivers/Protocols/CMSIS-DAP/VendorSpecific/EDBG/AVR/EdbgAvr8Interface.hpp b/src/DebugToolDrivers/Protocols/CMSIS-DAP/VendorSpecific/EDBG/AVR/EdbgAvr8Interface.hpp
index 3cb5714b..c81e6a40 100644
--- a/src/DebugToolDrivers/Protocols/CMSIS-DAP/VendorSpecific/EDBG/AVR/EdbgAvr8Interface.hpp
+++ b/src/DebugToolDrivers/Protocols/CMSIS-DAP/VendorSpecific/EDBG/AVR/EdbgAvr8Interface.hpp
@@ -537,6 +537,13 @@ namespace Bloom::DebugToolDrivers::Protocols::CmsisDap::Edbg::Avr
          */
         void writeMemory(Avr8MemoryType type, std::uint32_t address, const Targets::TargetMemoryBuffer& buffer);
 
+        /**
+         * Erases a particular region of memory, depending on the value of mode.
+         *
+         * @param mode
+         */
+        void eraseMemory(Avr8EraseMemoryMode mode);
+
         /**
          * Fetches the current target state.
          *