Support long long on stm32

The linker flag `-specs=nano.specs` has been removed by default to support the use of `long long` integers in `newlib`, and correct `printf` formatting. The `nano newlib` can still be used by passing `-DAVM_NEWLIB_NANO=on` to cmake when configuring the build. Signed-off-by: Winford <[email protected]>
atomvm · Aug 20, 2023 · 42cc656 · 42cc656
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diff --git a/doc/src/build-instructions.md b/doc/src/build-instructions.md
@@ -529,6 +529,8 @@ If you are building for a different target board the `CLOCK_FREQUENCY` definitio
 The rcc_clock_setup_XXX_XXX will also need to be changed to match your particular chip-set. Consult [ST's documentation](https://www.st.com/en/microcontrollers-microprocessors/stm32-32-bit-arm-cortex-mcus.html) for appropriate settings.
 
 ### Printing
+AtomVM is built with standard `newlib` to support `long long` integers (`signed` and `unsigned`). If you are building for a device with extremely limited flash space the `nano` version of `newlib` can be used instead. This will save approximately 46kB of flash. This may be done by passing `-DAVM_NEWLIB_NANO=on`.
+
 By default, stdout and stderr are printed on USART2. On the STM32F4Discovery board, you can see them
 using a TTL-USB with the TX pin connected to board's pin PA2 (USART2 RX). Baudrate is 115200 and serial transmission
 is 8N1 with no flow control.

diff --git a/src/platforms/stm32/CMakeLists.txt b/src/platforms/stm32/CMakeLists.txt
@@ -28,9 +28,14 @@ set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR})
 option(AVM_USE_32BIT_FLOAT "Use 32 bit floats." OFF)
 option(AVM_VERBOSE_ABORT "Print module and line number on VM abort" OFF)
 option(AVM_CREATE_STACKTRACES "Create stacktraces" ON)
+option(AVM_NEWLIB_NANO "Use 'nano' newlib. Saves 46kB, no `long long` support" OFF)
 
 set(AVM_DISABLE_SMP ON FORCE)
 
+if (AVM_NEWLIB_NANO)
+    set(LINKER_FLAGS "${LINKER_FLAGS} -specs=nano.specs")
+endif()
+
 # Include an error in case the user forgets to specify ARM as a toolchain
 if (NOT CMAKE_TOOLCHAIN_FILE)
     message(FATAL_ERROR "Cross compiling only. Please use -DCMAKE_TOOLCHAIN_FILE=cmake/arm-toolchain.cmake or use\

diff --git a/src/platforms/stm32/cmake/libopencm3.cmake b/src/platforms/stm32/cmake/libopencm3.cmake
@@ -145,7 +145,7 @@ message(STATUS "Generated Linker File   : ${CMAKE_CURRENT_BINARY_DIR}/${LINKER_S
 # ARCH_FLAGS has to be passed as a string here
 JOIN("${ARCH_FLAGS}" " " ARCH_FLAGS)
 # Set linker flags
-set(LINKER_FLAGS "${LINKER_FLAGS} -specs=nosys.specs -specs=nano.specs -nostartfiles -Wl,--undefined,_printf_float -Wl,--undefined,_scanf_float -T${CMAKE_CURRENT_BINARY_DIR}/${LINKER_SCRIPT} ${ARCH_FLAGS}")
+set(LINKER_FLAGS "${LINKER_FLAGS} -specs=nosys.specs -nostartfiles -Wl,--undefined,_printf_float -Wl,--undefined,_scanf_float -T${CMAKE_CURRENT_BINARY_DIR}/${LINKER_SCRIPT} ${ARCH_FLAGS}")
 message(STATUS "Linker Flags            : ${LINKER_FLAGS}")
 
 # Compiler flags