Improve async CDROM support #888
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This stuff doesn't belong here, and prevents other emulators using libpcsxcore from implementing the new async CDROM API properly. Signed-off-by: Paul Cercueil <[email protected]>
Rename cdrom_read_sector() to rcdrom_readSector(), and cdrom_is_media_inserted() to rcdrom_isMediaInserted() to match the rest of the "rcdrom" API. Update rcdrom_open() to return a handle, which will then be passed around to every other rcdrom API call. Signed-off-by: Paul Cercueil <[email protected]>
Add function rcdrom_readSub(), that can be implemented by frontends, and update rcdrom_open() to take an extra parameter, that can be set by the frontend to tell the async CD-ROM code whether or not subchannel reads are supported. Signed-off-by: Paul Cercueil <[email protected]>
Libretro threads only work on... libretro. Add support for C11 threads for the non-libretro platforms that still want the async CD-ROM code. Signed-off-by: Paul Cercueil <[email protected]>
An empty path string previously meant we were going to use the hardware CD-ROM. This is obvious when looking at the UsingIso() function for instance. Signed-off-by: Paul Cercueil <[email protected]>
Align the address and size of read buffers to 64 bytes, which should be bigger or equal than the size of the cache lines on most systems. This allows hardware CD-ROM implementations to perform reads using DMA, which generally have tight requirements on alignment. Signed-off-by: Paul Cercueil <[email protected]>
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Subchannel support was intentionally omitted as the prefetcher is unable to handle it now and I left it to be faked by the fallback code instead. The way PSX works is that the subchannel data is from a few sectors ahead of the data sector accessible through the FIFO, and the prefetcher always throws older sectors out right now, causing seeks back and forth making it all unusable on PC. That said from what I see you only set have_subchannel to 0 for libretro so it shouldn't hurt the usual targets. Still I'll want to test this on PC cdrom before merging. |
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Would it help if the subchannel data for a sector was read in (and returned from) the |
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It would help but it also needs to be updated to prevent it evicting the current data sector. It's now possible to select the buffer size of 0 or 1 sectors which won't work as-is. Anyway applied this to my main repo (+a double-free fix), will merge here some other time. |
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@notaz the reason I'm asking, is that on Dreamcast at least, you need to read a sector first to be able to get its subchannel data, so it makes sense to read both at the same time. I can imagine it works like that on PC drives as well. And if it permits to simplify things in PCSX that's even better. |
This allows me to use the async. CDROM functionality with ISOs and hardware CD-ROM in my Bloom downstream PSX emulator for Dreamcast.
Note that I suspect the async CDROM code to be slightly buggy, regarding subchannel data. If I enable subchannel reads in my CDROM driver (set
acdrom.have_subchannel), libcrypt games will boot (FF8 in my case) properly, but some other games (original copy of Need for Speed) won't boot unless disabled.