diff --git a/vm/bytepatch.go b/vm/bytepatch.go index eeddf62..3e6dea8 100644 --- a/vm/bytepatch.go +++ b/vm/bytepatch.go @@ -42,6 +42,11 @@ func Encode(patch sointu.Patch, featureSet FeatureSet) (*BytePatch, error) { globalAddrs := map[int]uint16{} globalFixups := map[int]([]int){} voiceNo := 0 + delayTable, delayIndices := constructDelayTimeTable(patch) + c.DelayTimes = make([]uint16, len(delayTable)) + for i := range delayTable { + c.DelayTimes[i] = uint16(delayTable[i]) + } for instrIndex, instr := range patch { if len(instr.Units) > 63 { return nil, errors.New("An instrument can have a maximum of 63 units") @@ -52,7 +57,7 @@ func Encode(patch sointu.Patch, featureSet FeatureSet) (*BytePatch, error) { localAddrs := map[int]uint16{} localFixups := map[int]([]int){} localUnitNo := 0 - for _, unit := range instr.Units { + for unitIndex, unit := range instr.Units { if unit.Type == "" { // empty units are just ignored & skipped continue } @@ -167,28 +172,7 @@ func Encode(patch sointu.Patch, featureSet FeatureSet) (*BytePatch, error) { continue // skip encoding delays without any delay lines } countTrack := count*2 - 1 + unit.Parameters["notetracking"] // 1 means no note tracking and 1 delay, 2 means notetracking with 1 delay, 3 means no note tracking and 2 delays etc. - matchIndex := -1 - for i := 0; i <= len(c.DelayTimes)-len(unit.VarArgs); i++ { - match := true - for j, v := range unit.VarArgs { - if uint16(v) != c.DelayTimes[i+j] { - match = false - break - } - } - if match { - matchIndex = i - break - } - } - if matchIndex > -1 { - values = append(values, byte(matchIndex), byte(countTrack)) - } else { - values = append(values, byte(len(c.DelayTimes)), byte(countTrack)) - for _, v := range unit.VarArgs { - c.DelayTimes = append(c.DelayTimes, uint16(v)) - } - } + values = append(values, byte(delayIndices[instrIndex][unitIndex]), byte(countTrack)) } c.Commands = append(c.Commands, byte(opcode+unit.Parameters["stereo"])) c.Values = append(c.Values, values...) diff --git a/vm/delaytable.go b/vm/delaytable.go new file mode 100644 index 0000000..afed1d9 --- /dev/null +++ b/vm/delaytable.go @@ -0,0 +1,143 @@ +package vm + +import "github.com/vsariola/sointu" + +// findSuperIntArray finds a small super array containing all +// the subarrays passed to it. Returns the super array and indices where +// the subarrays can be found. For example: +// FindSuperIntArray([][]int{{4,5,6},{1,2,3},{3,4}}) +// returns {1,2,3,4,5,6},{3,0,2} +// Implemented using a greedy search, so does not necessarily find +// the true optimal (the problem is NP-hard and analogous to traveling +// salesman problem). +// +// Used to construct a small delay time table without unnecessary repetition +// of delay times. +func findSuperIntArray(arrays [][]int) ([]int, []int) { + // If we go past MAX_MERGES, the algorithm could get slow and hang the computer + // So this is a safety limit: after this problem size, just merge any arrays + // until we get into more manageable range + const maxMerges = 1000 + min := func(a int, b int) int { + if a < b { + return a + } + return b + } + overlap := func(a []int, b []int) (int, int) { + minShift := len(a) + for shift := len(a) - 1; shift >= 0; shift-- { + overlapping := true + for k := shift; k < min(len(a), len(b)+shift); k++ { + if a[k] != b[k-shift] { + overlapping = false + break + } + } + if overlapping { + minShift = shift + } + } + overlap := min(len(a)-minShift, len(b)) + return overlap, minShift + } + sliceNumbers := make([]int, len(arrays)) + startIndices := make([]int, len(arrays)) + var processedArrays [][]int + for i := range arrays { + if len(arrays[i]) == 0 { + // Zero length arrays do not need to be processed at all + // They will 'start' at index 0 always as they have no length. + sliceNumbers[i] = -1 + } else { + sliceNumbers[i] = len(processedArrays) + processedArrays = append(processedArrays, arrays[i]) + } + } + if len(processedArrays) == 0 { + return []int{}, startIndices // no arrays with len>0 to process, just return empty array and all indices as 0 + } + for len(processedArrays) > 1 { // there's at least two candidates that could be be merged + maxO, maxI, maxJ, maxS := -1, -1, -1, -1 + if len(processedArrays) < maxMerges { + // find the pair i,j that results in the largest overlap with array i coming first, followed by potentially overlapping array j + for i := range processedArrays { + for j := range processedArrays { + if i == j { + continue + } + overlap, shift := overlap(processedArrays[i], processedArrays[j]) + if overlap > maxO { + maxI, maxJ, maxO, maxS = i, j, overlap, shift + } + } + } + } else { + // The task is daunting, we have over MAX_MERGES overlaps to test. Just merge two first ones until the task is more manageable size + overlap, shift := overlap(processedArrays[0], processedArrays[1]) + maxI, maxJ, maxO, maxS = 0, 1, overlap, shift + } + for k := range sliceNumbers { + if sliceNumbers[k] == maxJ { + // update slice pointers to point maxI instead of maxJ (maxJ will be appended to maxI, taking overlap into account) + sliceNumbers[k] = maxI + startIndices[k] += maxS // the array j starts at index maxS in array i + } + if sliceNumbers[k] > maxJ { + // pointers maxJ reduced by 1 as maxJ will be deleted + sliceNumbers[k]-- + } + } + // if array j was not entirely included within array j + if maxO < len(processedArrays[maxJ]) { + // append array maxJ to array maxI, without duplicating the overlapping part + processedArrays[maxI] = append(processedArrays[maxI], processedArrays[maxJ][maxO:]...) + } + // finally, remove element maxJ from processedArrays + processedArrays = append(processedArrays[:maxJ], processedArrays[maxJ+1:]...) + } + return processedArrays[0], startIndices // there should be only one slice left in the arrays after the loop +} + +// constructDelayTimeTable tries to construct the delay times table abusing +// overlapping between different delay times tables as much as possible. +// Especially: if two delay units use exactly the same delay times, they appear +// in the table only once. +// +// Returns the delay time table and two dimensional array of integers where +// element [i][u] is the index for instrument i / unit u in the delay table if +// the unit was a delay unit. For non-delay untis, the element is just 0. +func constructDelayTimeTable(patch sointu.Patch) ([]int, [][]int) { + ind := make([][]int, len(patch)) + var subarrays [][]int + // flatten the delay times into one array of arrays + // saving the indices where they were placed + for i, instr := range patch { + ind[i] = make([]int, len(instr.Units)) + for j, unit := range instr.Units { + // only include delay times for delays. Only delays + // should use delay times + if unit.Type == "delay" { + ind[i][j] = len(subarrays) + end := unit.Parameters["count"] + if unit.Parameters["stereo"] > 0 { + end *= 2 + } + subarrays = append(subarrays, unit.VarArgs) + } + } + } + delayTable, indices := findSuperIntArray(subarrays) + // cancel the flattening, so unitindices can be used to + // to find the index of each delay in the delay table + unitindices := make([][]int, len(patch)) + for i, instr := range patch { + unitindices[i] = make([]int, len(instr.Units)) + for j, unit := range instr.Units { + if unit.Type == "delay" { + unitindices[i][j] = indices[ind[i][j]] + } + } + } + return delayTable, unitindices +}