WIP: Port "Gameboy sound hardware" from the old wiki #562
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src/Audio_Registers.md
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| :::warning RETRIGGERING CAUTION | ||
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| On monochrome consoles only, retriggering CH3 while it's about to read a byte from wave RAM causes wave RAM to be corrupted in a generally unpredictable manner. | ||
| On monochrome consoles only, retriggering CH3 while it's about to read a byte from wave RAM causes wave RAM to be corrupted in a generally unpredictable manner. | ||
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| :::warning PLAYBACK DELAY | ||
| :::warning PLAYBACK DELAY | ||
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| Triggering the wave channel does not immediately start playing wave RAM; instead, the *last* sample ever read (which is reset to 0 when the APU is off) is output until the channel next reads a sample. | ||
| ([Source](https://github.com/LIJI32/SameSuite/blob/master/apu/channel_3/channel_3_delay.asm)) | ||
| Triggering the wave channel does not immediately start playing wave RAM; instead, the *last* sample ever read (which is reset to 0 when the APU is off) is output until the channel next reads a sample. | ||
| ([Source](https://github.com/LIJI32/SameSuite/blob/master/apu/channel_3/channel_3_delay.asm)) | ||
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Wouldn't unindenting those break the list in two?
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With the last commit the warnings are nested 2 levels deep in the sublist.
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@ISSOtm would you say we can start merging and afterwards "check" the statements ? For "critical ones" we could directly add notes/earnings asking for help to verify the statements |
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I don't know. The risk of adding false statements to Pan Docs always exists, and is a regression of sorts. I'd like to fix them from the get-go if the resources (primarily motivation) are available, but if not, then yes we'll merge this and improve later. |
Sure, for now I've been using SameBoy source as a reference but I don't know if there's a better source for checking the statements of the old wiki. |
Co-authored-by: Eldred Habert <[email protected]>
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SameBoy's source is one of the best references, since it's accurate, well-tested, and often well commented; but since it's code, it's still subject to interpretation. That's why we prefer citing test ROMs (when possible). But “best effort“ remains in effect, so only verifying against SameBoy's source is perfectly fine, and hey, still miles better than just blindly copy-pasting some text! ^^ |
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Ok, I'll see if I can find some test ROMs, specially for the "obscure behavior" claims. |
| @@ -202,7 +204,15 @@ Period changes (written to `NR13` or `NR14`) only take effect after the current | |||
| "NR14" 7:"Trigger" 6:"Length enable" 2-0:"Period" | |||
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| - **Trigger** (*Write-only*): Writing any value to `NR14` with this bit set [triggers](<#Triggering>) the channel. | |||
| - **Trigger** (*Write-only*): Writing any value to `NR14` with this bit set [triggers](<#Triggering>) the channel, causing the | |||
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Maybe we can improve this wording a bit? "triggering a channel"
| optionally negating the value, depending on the [direction](<#FF10 — NR10: Channel 1 sweep>), and summing this with the frequency "shadow register" to produce a new frequency. | ||
| What is done with this new frequency depends on the context. | ||
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| The _overflow check_ simply calculates the new frequency and if it is greater than 2047, or $7FF, CH1 is disabled. |
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minor: this section may enjoy a flow diagram?
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Have you been able to find any test ROMs? If not, that's fine, then SameBoy would be quite sufficient. |
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@remind-me-later do you have any update on this? It's fine to just mention SameBoy for the time being, we can open an issue for the test roms |
I've seen that the blargg test roms check for some of the behavior of the sweep (cgb-sound tests 04-sweep and 05-sweep details) which seem to coincide with the behavior described. The test 03-trigger also matches the added text about triggering a channel. The parts I'm less sure of are some claims in the obscure behavior section, for example the zombie step paragraph, I've tried reading SameBoy's source about this but couldn't quite get how this mode works. |
Closes #552. Each section from the old wiki corresponds to a commit.
I encountered the following issues while porting some sections:
doesn't match with SameBoy source, and I think that's more accurate.
is useful, so I skipped it.
and Audio Details, but I don't know if that would make the rest of the section more bothersome
to read.
so I skipped them as well.