From a9937b94e23ad1555ecfad4d57394623d4fb4407 Mon Sep 17 00:00:00 2001
From: Yuri D'Elia <wavexx@thregr.org>
Date: Sat, 3 Jul 2021 19:43:27 +0200
Subject: [PATCH] Add initial AVR PROGMEM abstraction in hal::progmem

---
 src/hal/progmem.h                       | 26 +++++++++++++++++++++++++
 tests/unit/hal/CMakeLists.txt           |  1 +
 tests/unit/hal/progmem/CMakeLists.txt   |  8 ++++++++
 tests/unit/hal/progmem/test_progmem.cpp | 15 ++++++++++++++
 4 files changed, 50 insertions(+)
 create mode 100644 src/hal/progmem.h
 create mode 100644 tests/unit/hal/progmem/CMakeLists.txt
 create mode 100644 tests/unit/hal/progmem/test_progmem.cpp

diff --git a/src/hal/progmem.h b/src/hal/progmem.h
new file mode 100644
index 0000000..c67106e
--- /dev/null
+++ b/src/hal/progmem.h
@@ -0,0 +1,26 @@
+#pragma once
+#include <stdint.h>
+
+#ifdef __AVR__
+#include <avr/progmem.h>
+#else
+#define PROGMEM // ignored
+#endif
+
+namespace hal {
+
+/// AVR PROGMEM handling
+namespace progmem {
+
+/// read a 16bit word from PROGMEM
+static inline uint16_t pgm_read_word(const uint16_t* addr)
+{
+#ifndef __AVR__
+    return *addr;
+#else
+    return (uint16_t)::pgm_read_word(addr);
+#endif
+}
+
+} // namespace progmem
+} // namespace hal
diff --git a/tests/unit/hal/CMakeLists.txt b/tests/unit/hal/CMakeLists.txt
index ce3c840..eb7d50c 100644
--- a/tests/unit/hal/CMakeLists.txt
+++ b/tests/unit/hal/CMakeLists.txt
@@ -1 +1,2 @@
 add_subdirectory(circular_buffer)
+add_subdirectory(progmem)
diff --git a/tests/unit/hal/progmem/CMakeLists.txt b/tests/unit/hal/progmem/CMakeLists.txt
new file mode 100644
index 0000000..8567655
--- /dev/null
+++ b/tests/unit/hal/progmem/CMakeLists.txt
@@ -0,0 +1,8 @@
+# define the test executable
+add_executable(progmem_tests test_progmem.cpp)
+
+# define required search paths
+target_include_directories(progmem_tests PUBLIC ${CMAKE_SOURCE_DIR}/src/hal)
+
+# tell build system about the test case
+add_catch_test(progmem_tests)
diff --git a/tests/unit/hal/progmem/test_progmem.cpp b/tests/unit/hal/progmem/test_progmem.cpp
new file mode 100644
index 0000000..abd54f7
--- /dev/null
+++ b/tests/unit/hal/progmem/test_progmem.cpp
@@ -0,0 +1,15 @@
+#include "catch2/catch.hpp"
+#include "progmem.h"
+
+using Catch::Matchers::Equals;
+using hal::progmem::pgm_read_word;
+
+TEST_CASE("progmem::basic", "[progmem]") {
+
+    // create a PROGMEM array
+    const uint16_t arr[2] PROGMEM = {0, 1};
+
+    // ensure it can be read correctly
+    REQUIRE(0 == pgm_read_word(&arr[0]));
+    REQUIRE(1 == pgm_read_word(&arr[1]));
+}