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tracker impl

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minjaesong
2026-04-17 12:03:43 +09:00
parent 7d899936e2
commit 8702104bfe
5 changed files with 333 additions and 63 deletions
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25
assets/disk0/tvdos/include/psg.mjs
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@@ -81,9 +81,12 @@ function clearBuffer(buf, offsetSec, lengthSec) {
// Re-silence a buffer region (fill with 128) for re-use across frames.
const start = (offsetSec != null) ? secToSamples(offsetSec) : 0
const total = (lengthSec != null) ? secToSamples(lengthSec) : (buf.samples - start)
for (let i = 0; i < total; i++) {
writeU8(buf, 0, start + i, 128)
writeU8(buf, 1, start + i, 128)
if (!buf.native) {
buf[0].fill(128, start, start + total)
buf[1].fill(128, start, start + total)
} else {
sys.memset(buf[0] + start, 128, total)
sys.memset(buf[1] + start, 128, total)
}
}
@@ -142,7 +145,7 @@ function makeSquare(buf, length, offset, freq, duty, op, amp, pan, phaseOffset)
})
}
function makeTriangle(buf, length, offset, freq, duty, op, amp, pan) {
function makeTriangle(buf, length, offset, freq, duty, op, amp, pan, phaseOffset) {
// buffer: [Uint8Array, Uint8Array] or native buffer
// length: in seconds
// offset: in seconds
@@ -151,6 +154,8 @@ function makeTriangle(buf, length, offset, freq, duty, op, amp, pan) {
// op: add / mul / sub; default: add
// amp: 0.0 to 1.0; default: 0.5
// pan: -1.0 to 1.0; default: 0.0
// phaseOffset: optional absolute-time base (seconds) added to phase calc only —
// see makeSquare for details.
if (duty == null) duty = 0.0
if (op == null) op = 'add'
if (amp == null) amp = 0.5
@@ -158,9 +163,9 @@ function makeTriangle(buf, length, offset, freq, duty, op, amp, pan) {
// riseFrac: fraction of period spent rising from -1 to +1
// 0.0 → falling saw, 0.5 → symmetric triangle, 1.0 → rising saw
const riseFrac = (duty + 1.0) * 0.5
const tBase = (phaseOffset || 0) + offset
mixInto(buf, length, offset, op, amp, pan, function(i) {
const t = offset + i / HW_SAMPLING_RATE
const phase = (t * freq) % 1
const phase = ((tBase + i / HW_SAMPLING_RATE) * freq) % 1
if (riseFrac <= 0) {
return 1.0 - 2.0 * phase // falling saw
} else if (riseFrac >= 1) {
@@ -173,7 +178,7 @@ function makeTriangle(buf, length, offset, freq, duty, op, amp, pan) {
})
}
function makeAliasedTriangle(buf, length, offset, freq, duty, op, amp, pan) {
function makeAliasedTriangle(buf, length, offset, freq, duty, op, amp, pan, phaseOffset) {
// buffer: [Uint8Array, Uint8Array] or native buffer
// Famicom-style triangle — output is quantised to 16 DAC levels (4-bit, NES APU style).
// The staircase quantisation introduces harmonics that mimic NES character.
@@ -184,14 +189,16 @@ function makeAliasedTriangle(buf, length, offset, freq, duty, op, amp, pan) {
// op: add / mul / sub; default: add
// amp: 0.0 to 1.0; default: 0.5
// pan: -1.0 to 1.0; default: 0.0
// phaseOffset: optional absolute-time base (seconds) added to phase calc only —
// see makeSquare for details.
if (duty == null) duty = 0.0
if (op == null) op = 'add'
if (amp == null) amp = 0.5
if (pan == null) pan = 0.0
const riseFrac = (duty + 1.0) * 0.5
const tBase = (phaseOffset || 0) + offset
mixInto(buf, length, offset, op, amp, pan, function(i) {
const t = offset + i / HW_SAMPLING_RATE
const phase = (t * freq) % 1
const phase = ((tBase + i / HW_SAMPLING_RATE) * freq) % 1
let v
if (riseFrac <= 0) {
v = 1.0 - 2.0 * phase