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== Application Program Compilation

This guide shows how to compile an example C-code application into a NEORV32 executable that

can be uploaded via the bootloader or the on-chip debugger.

[IMPORTANT]

If your FPGA board does not provide such an interface - don't worry!

Section <<_installing_an_executable_directly_into_memory>> shows how to

run custom programs on your FPGA setup without having a UART.

[start=1]

. Open a terminal console and navigate to one of the project's example programs. For instance, navigate to the

simple `sw/example_blink_led` example program. This program uses the NEORV32 GPIO module to display

an 8-bit counter on the lowest eight bit of the `gpio_o` output port.

. To compile the project and generate an executable simply execute:

[source,bash]

----

neorv32/sw/example/blink_led$ make clean_all exe

----

[start=3]

. We are using the `clean_all` target to make sure everything is re-build.

. This will compile and link the application sources together with all the included libraries. At the end,

your application is transformed into an ELF file (`main.elf`). The _NEORV32 image generator_ (in `sw/image_gen`)

takes this file and creates a final executable. The makefile will show the resulting memory utilization and

the executable size:

[source,bash]

----

neorv32/sw/example/blink_led$ make clean_all exe

Memory utilization:

   text    data     bss     dec     hex filename

   3176       0     120    3296     ce0 main.elf

Compiling ../../../sw/image_gen/image_gen

Executable (neorv32_exe.bin) size in bytes:

3188

----

[NOTE]

Make sure the size of the `text` segment (3176 bytes here) does not overflow the size of the processor's

IMEM (if used at all) - otherwise there will be an error during synthesis or during bootloader upload.

[start=5]

. That's it. The `exe` target has created the actual executable `neorv32_exe.bin` in the current folder

that is ready to be uploaded to the processor.

[TIP]

The compilation process will also create a `main.asm` assembly listing file in the current folder, which

shows the actual assembly code of the application.