fx_decay
#define fx_env1_release fx_decay /* [0,5940] 4msec */
#define fx_env2_decay fx_decay /* [0,5940] 4msec */
#define fx_env2_release fx_decay /* [0,5940] 4msec */
static int fx_decay(int val);
#define fx_env1_decay fx_decay /* [0,5940] 4msec */