3ca5f193e6c4023a208f2ba941044edda7c68cf3
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Commits
| Author | SHA1 | Message | Date | |
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 Anachronaut
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3ca5f193e6 |
The warning's trill, and why it only sometimes came out
An LFO belongs to the DEVICE and not to a channel. There are two of them against four voices, and a patch carries LFO settings the way it carries everything else - so whichever patch was loaded last owns both of them, for every voice at once. The warning's trill is a saw LFO on the pitch. The patches on channel three, the bang and the latch, carry an LFO that is switched off, and they load at the moment they are used. So the first landing, docking or crash of a run took the trill away and left a plain tone, and it was right again next time the machine started. Correct until something unrelated plays is the worst shape a fault can have. The same thing had already happened silently at startup: the instruments were set up in order, so the warning's LFO settings, written last, sat on top of the rumble's and the rumble never had its own at all. So nothing is set up once any more. Each sound loads its patch immediately before its note - forty-odd writes at a moment already making a sound - and is then whatever its patch says, whatever played before it. Measured after a landing: 1056, 660, 516 hertz, then up to 1698 and down again. Two sweeps of the saw, which is the trill. What it does not fix, because it cannot: two sounds overlapping still share the LFOs, so a warning going off mid-burn re-tunes the rumble for as long as it lasts. With two between four that is the device. Three checks at the device level, where the trap can be stated exactly: a routed LFO bends a pitch (184 Hz against the 262 the note asked for), another channel's patch takes it away (272, the note itself), and saying it again gets it back (184). Written up in the Programming Manual beside the LFO mode, since the next program to want two sounds will meet it too. |
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Anachronaut
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b2ff8d64e5 |
Fold soundThing's changes back down, and expose the two new switches
The three changes that went up came back as part of soundThing, along with two more that they made possible. The engine here is now b73e5c0 character for character, except that em-dashes and arrows in comments are written as ASCII because this tree is ASCII only - a local rule, not an improvement, and not sent up. So synth.h's "what was changed" list is gone. There is nothing to list: what has to be kept current is only that if either copy changes, the other one has to be told. ---- What came back ---- A VOICE CAN END ITSELF. Naming the level's source said what shapes a voice; nothing said what ends one, so the only thing that could ever finish one was a key coming up. A game is nearly all one-shots and not one of them wants its length decided by how long a note was held. Exposed as parameter 0x51: 0 gated, 1 triggered. AND A ONE-SHOT IS THE SAME ONE-SHOT TWICE. A triggered voice re-arms its oscillators, and an LFO can be told to start over with each voice - parameter 3 of either LFO. Both halves are needed and the check proves it: with the LFO left free, two triggered hits still differ. Their note warned that whatever applies a patch to a channel has to set these or they hold synthInit's defaults. Checked: Voyager never calls synthSyncVoices, so their 0001 is a no-op here as they predicted, and nothing reaches into an LFO's phase, so the struct split is safe. ---- What it is for ---- Lander's crash is a triggered voice now, so boomOff is gone. Nothing has to remember to end a bang. SoundPatch learnt voice_levelSource, voice_gate and lfo<N>_mode, which the new soundThing writes - without that it would have refused every patch saved from it, since an unknown field stops the tool on purpose. A patch from before those fields still converts, and says in its own comments that it predates the level routing. Three checks, each seen to fail on its own break: a gated voice still sounding with nothing holding it, a triggered one down to nothing with no gate ever dropped, and two hits identical sample for sample. One test bug worth keeping: the first version of the repeatability check struck the second note while the first was still ringing, so what it found and compared as "the second hit" was a point in the middle of the first one's tail. It now looks for sound after SILENCE rather than sound after an offset. |
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 AnachronautandClaude Opus 5
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d388cd3122 |
Give the machine a sound device
Four channels on ports 0x40 to 0x4F, each one a whole soundThing voice:
two oscillators, two envelopes, a filter and the routing between them. A
channel keeps its patch between notes, so a program sets an instrument up
once and then plays it.
Six ports rather than forty, because a voice has around forty settings and
four of them would spend more than half the port space on one device.
There is a selector and a value instead: say which channel, say which
setting, write it. That is three writes to change a setting and two to
play a note, which is the right way round - patches are loaded, notes are
played in an inner loop.
Samples come from the machine's clock and not the host's: 48,000 a second
of emulated time, worked out in whole numbers so it never drifts. A
million cycles is exactly 48,000 samples on any host at any speed, which
is what makes a sound something a test can compare. --sound writes them
out, the way --screen writes a picture, for the same reason: the suite has
no speaker.
Tests/sound.sh is 22 checks and found three real defects the first time it
ran, all the same shape - a synthesizer written for a patch editor, wired
up as hardware and inheriting the editor's assumptions:
- Only one voice had an oscillator switched on, so three of the four
channels could not make a sound whatever was written to them.
- That voice's oscillator arrived at full gain and every other one
arrived at nothing, an asymmetry with no reason behind it.
- A note with no sustain is silent but not over, so the obvious way to
wait for a sound to finish waits for ever.
The first two are fixed by the device defining its own power-on state
rather than inheriting synthInit's: every channel arrives able to make a
sound, so writing a note number is the whole of playing a note. The third
was already written into the manual as advice, an hour before the check
existed. The check disagreed with the documentation and the check was
right; the manual now says the one rule, which is that a note sounds until
the gate is dropped.
Programs/Examples/tune.asm plays eight notes, taking its tempo from the
screen's frame interrupt because that is the only regular beat this
machine has. It spends 99.8% of its cycles asleep in WAIT.
Voyager has no speaker yet - this is the device and its tests. Playing the
samples out of the window is the next commit.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW
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