/
glide.go
128 lines (113 loc) · 2.47 KB
/
glide.go
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package module
import (
"math"
"buddin.us/eolian/dsp"
"github.com/mitchellh/mapstructure"
)
func init() {
Register("Glide", func(c Config) (Patcher, error) {
var config struct {
Rise, Fall float64
}
if err := mapstructure.Decode(c, &config); err != nil {
return nil, err
}
if config.Rise == 0 {
config.Rise = 5
}
if config.Fall == 0 {
config.Fall = 5
}
return newGlide(config.Rise, config.Fall)
})
}
type glide struct {
IO
in, rise, fall *In
*slew
}
func newGlide(rise, fall float64) (*glide, error) {
m := &glide{
in: NewIn("input", dsp.Float64(0)),
rise: NewInBuffer("rise", dsp.Duration(rise)),
fall: NewInBuffer("fall", dsp.Duration(fall)),
slew: newSlew(),
}
err := m.Expose(
"Glide",
[]*In{m.in, m.rise, m.fall},
[]*Out{{Name: "output", Provider: dsp.Provide(m)}},
)
return m, err
}
func (g *glide) Process(out dsp.Frame) {
g.in.Process(out)
rise, fall := g.rise.ProcessFrame(), g.fall.ProcessFrame()
for i := range out {
out[i] = g.slew.Tick(out[i], rise[i], fall[i])
}
}
type slewStateFunc func(*slewState) slewStateFunc
type slewState struct {
value, in, lastIn dsp.Float64
from, to dsp.Float64
rise, fall dsp.Float64
}
type slew struct {
stateFunc slewStateFunc
state *slewState
}
func newSlew() *slew {
return &slew{slewIdle, &slewState{}}
}
func (s *slew) Tick(v, rise, fall dsp.Float64) dsp.Float64 {
s.state.lastIn, s.state.in = s.state.in, v
s.state.rise, s.state.fall = rise, fall
s.stateFunc = s.stateFunc(s.state)
return s.state.value
}
func slewIdle(s *slewState) slewStateFunc {
if s.lastIn == 0 && s.in != 0 {
s.value = s.in
return slewIdle
}
if s.in != s.lastIn && dsp.Abs(s.in-s.lastIn) > dsp.Float64(math.SmallestNonzeroFloat64) {
s.from, s.to = s.lastIn, s.in
s.lastIn = s.in
s.value = s.from
return slewTransition
}
return slewIdle
}
func slewTransition(s *slewState) slewStateFunc {
if s.in != s.lastIn {
s.from, s.to = s.lastIn, s.in
}
var (
d = s.to - s.from
amount dsp.Float64
)
if d < 0 {
if s.fall == 0 {
return slewFinish
}
amount = d / s.fall
} else if d > 0 {
if s.rise == 0 {
return slewFinish
}
amount = d / s.rise
} else if dsp.Abs(d) < dsp.Float64(math.SmallestNonzeroFloat64) {
return slewFinish
}
s.value += amount
remain := s.value - s.to
if (d > 0 && remain >= 0) || (d < 0 && remain <= 0) {
return slewFinish
}
return slewTransition
}
func slewFinish(s *slewState) slewStateFunc {
s.value = s.to
return slewIdle
}