Fun with frequencies

freq.sh

#!/usr/bin/env zsh
# Mon Dec 23 05:48:33 CET 2013
# 2013 (c) [email protected]

# plays frequencies

f=${1:=440}
pids=()

freq() {
	case $1 in
		+*|-*) f=$(($f$1)) ;;
		*) f=$1 ;;
	esac
	[[ $f -lt 0 ]] && return
	[[ ! -z $pid ]] && kill $pid
	nohup play -n synth sin $f >/dev/null &
	pid=$!
}

freq $f

while true; do
	printf "% 7d\r" $f;
	read -sk 1 key
	case $key in
		q) break ;;
		-) freq -1 ;;
		+|=) freq +1 ;;
		J) freq -10 ;;
		K) freq +10 ;;
		j) freq -100 ;;
		k) freq +100 ;;
		h) freq -1000 ;;
		l) freq +1000 ;;
		f) freq $((($f/10**$(($#f-1)))*10**$(($#f-1)))) ;; # floor to somewhere close
		c) freq 440 ;;
		t) freq 13333 ;;
		r) freq $[${RANDOM}%15000] ;;
		[0-9]) printf "\t%7d" $key; freq $key$(read -Er); echo -en "\r" ;;
		s) pids+=$pid; unset pid; echo "<< $f" ;; # save freq
	esac
done

kill $pid
for i in $pids; do kill $i >/dev/null; done
exit