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e0a793ea6d
Sointu.asm / lib stuff lives at the root folder. There is a folder called "go4k", which is where all go stuff lives. Following the ideas from https://medium.com/@benbjohnson/standard-package-layout-7cdbc8391fc1 the go4k folder is the "domain-model" of the go side, and should have no dependencies. It contains Unit, Instrument, Synth interface etc. Putting go4k under a sub-folder is actually in the spirit of Ben, as go4k adds dependency to the go language. Bridge ties the domain-model to the sointulib through cgo. It returns C.Synth, but makes sure the C.Synth implements the Synth interface, so others are able to use the Synth no matter how it actually is done. MockSynth and WebProxy synth are good prospects for other implementations of Synth. It is a bit fuzzy where methods like "Play" that have no dependencies other than domain model structs should go. They probably should live in the go4k package as well. The file-organization on the Go-side is not at all finalized. But how packages are broken into files is mostly a documentation issue; it does not affect the users of the packages at all. BTW: The name go4k was chosen because Ben advocated naming the subpackages according to the dependency they introduce AND because the prototype of 4klang was called go4k (there are still some defines in the 4klang source revealing this). go4k thus honors our roots but is also not so bad name: it's the main package of a 4k synth tracker, written in go.
108 lines
2.7 KiB
Go
108 lines
2.7 KiB
Go
package go4k
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import "errors"
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type Song struct {
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BPM int
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Patterns [][]byte
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Tracks []Track
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SongLength int // in samples, 0 means calculate automatically from BPM and Track lengths, but can also set manually
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Patch Patch
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}
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func (s *Song) PatternRows() int {
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return len(s.Patterns[0])
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}
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func (s *Song) SequenceLength() int {
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return len(s.Tracks[0].Sequence)
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}
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func (s *Song) TotalRows() int {
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return s.PatternRows() * s.SequenceLength()
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}
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func (s *Song) SamplesPerRow() int {
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return 44100 * 60 / (s.BPM * 4)
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}
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func (s *Song) FirstTrackVoice(track int) int {
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ret := 0
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for _, t := range s.Tracks[:track] {
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ret += t.NumVoices
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}
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return ret
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}
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// TBD: Where shall we put methods that work on pure domain types and have no dependencies
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// e.g. Validate here
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func (s *Song) Validate() error {
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if s.BPM < 1 {
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return errors.New("BPM should be > 0")
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}
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for i := range s.Patterns[:len(s.Patterns)-1] {
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if len(s.Patterns[i]) != len(s.Patterns[i+1]) {
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return errors.New("Every pattern should have the same length")
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}
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}
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for i := range s.Tracks[:len(s.Tracks)-1] {
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if len(s.Tracks[i].Sequence) != len(s.Tracks[i+1].Sequence) {
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return errors.New("Every track should have the same sequence length")
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}
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}
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totalTrackVoices := 0
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for _, track := range s.Tracks {
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totalTrackVoices += track.NumVoices
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for _, p := range track.Sequence {
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if p < 0 || int(p) >= len(s.Patterns) {
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return errors.New("Tracks use a non-existing pattern")
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}
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}
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}
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if totalTrackVoices > s.Patch.TotalVoices() {
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return errors.New("Tracks use too many voices")
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}
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return nil
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}
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func Play(synth Synth, song Song) ([]float32, error) {
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err := song.Validate()
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if err != nil {
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return nil, err
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}
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curVoices := make([]int, len(song.Tracks))
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for i := range curVoices {
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curVoices[i] = song.FirstTrackVoice(i)
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}
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samples := song.SongLength
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if samples <= 0 {
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samples = song.TotalRows() * song.SamplesPerRow()
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}
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buffer := make([]float32, samples*2)
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totaln := 0
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rowtime := song.SamplesPerRow()
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for row := 0; row < song.TotalRows(); row++ {
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patternRow := row % song.PatternRows()
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pattern := row / song.PatternRows()
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for t := range song.Tracks {
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patternIndex := song.Tracks[t].Sequence[pattern]
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note := song.Patterns[patternIndex][patternRow]
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if note == 1 { // anything but hold causes an action.
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continue // TODO: can hold be actually something else than 1?
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}
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synth.Release(curVoices[t])
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if note > 1 {
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curVoices[t]++
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first := song.FirstTrackVoice(t)
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if curVoices[t] >= first+song.Tracks[t].NumVoices {
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curVoices[t] = first
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}
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synth.Trigger(curVoices[t], note)
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}
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}
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samples, _, _ := synth.Render(buffer[2*totaln:], rowtime)
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totaln += samples
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}
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return buffer, nil
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}
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