add build and flash script

build.sh

@@ -0,0 +1,21 @@
+#!/bin/busybox ash
+set -e
+
+cargo +stable build --release
+
+output_dir="target/thumbv7m-none-eabi/release"
+output_name="spidump"
+
+llvm-size -d "$output_dir/$output_name" | (
+	read line
+	echo $line
+	read line
+	echo $line | sed -r ':L;s=\b([0-9]+)([0-9]{3})\b=\1K=g;t L'
+) | column -t -s' '
+
+llvm-objcopy -O binary "$output_dir/$output_name" "$output_dir/$output_name.bin"
+
+if [ "$(basename "$0")" == "flash.sh" ]; then
+	echo "Writing file $output_dir/$output_name.bin to device ..."
+	st-flash write "$output_dir/$output_name.bin" 0x8000000
+fi

flash.sh

@@ -0,0 +1 @@
+build.sh