removed old filter code

filter/Makefile

@@ -1,14 +0,0 @@
-all:
-	@arm-none-eabi-gcc -mcpu=cortex-m4 -mthumb -Os --specs=nosys.specs -nostartfiles -fPIE -c test.cpp
-	@arm-none-eabi-ld -shared -n -N -z max-page-size=512 -Ttext-segment=0 \
-	    test.o -o test.so
-	@arm-none-eabi-strip -s -S --strip-unneeded test.so
-	@arm-none-eabi-objcopy --remove-section .dynsym \
-						   --remove-section .dynstr \
-						   --remove-section .dynamic \
-						   --remove-section .hash \
-						   --remove-section .ARM.exidx \
-						   --remove-section .ARM.attributes \
-						   --remove-section .comment \
-						   test.so
-

filter/test.cpp

@@ -1,14 +0,0 @@
-#include <cstdint>
-
-using adcsample_t = uint16_t;
-__attribute__((section(".process_data")))
-void process_data(adcsample_t *samples, unsigned int size);
- 
-////////////////////////////////////////////////////////////////////////////////
-
-void process_data(adcsample_t *samples, unsigned int size)
-{
-    for (unsigned int i = 0; i < size; i++)
-        samples[i] /= 2;
-}
-