IOMD device numbers under HAL

On the System Device Numbers Wiki page it states:

The following table is only valid for IOMD-based pre-HAL machines. For machines with a HAL (even a HAL running on IOMD), programmers should make no assumption about device numbers following any fixed scheme. Instead, the appropriate OS calls or hardware-specific documentation should be used to determine the correct device numbers.

It’s not obvious from that how you’d go about getting the HAL device numbers for IOMD devices. I’m guessing OS_Hardware is probably the correct method, but there’s no detail on what R0 bits 0-15 – device type should be.

Is OS_Hardware the correct SWI I should be using? If so, what are the device types I need to call it with? The three IOMD devices I’m after are:

3 VSync Pulse
6 Timer 1
9 Sound system buffer change

* VSync Pulse
* Timer 1
* Sound system buffer change

Use HAL_TimerDevice (via OS_Hardware) to ask for timer 1’s IRQ device number.
Hunt for device HALDeviceID_VDU_VIDC20 (via OS_Hardware) to ask for the VSync IRQ device number.
For sound system, the SoundDMA module hasn’t been moved over as a HAL device so you’ll have to hardwire that for now, or perhaps speculatively try asking for HALDeviceAudio_AudC and falling back to 9 if that fails.

Thanks for that info, the next questions are:

1. Where do I find the values for “HALDeviceID_VDU_VIDC20” and “HALDeviceAudio_AudC” to pass to OS_Hardware?
2. What timer no. will Timer 1 have via HAL_TimerDevice. Will it be 1 or 2?

I searched the Wiki and even the OS source, but am still none the wiser!

1. Where do I find the values for “HALDeviceID_VDU_VIDC20” and “HALDeviceAudio_AudC” to pass to OS_Hardware?

These are all defined in Kernel.hdr.HALDevice

2. What timer no. will Timer 1 have via HAL_TimerDevice. Will it be 1 or 2?

That would be HAL timer 1 (HAL timers are numbered from zero, the same as IOMD timers)

These are all defined in Kernel.hdr.HALDevice

I’m still none the wiser :/, how does that table translate to a value?

HALDeviceID_VDU_VIDC20: This will correspond to calling OS_Hardware 4 with R0 = HALDeviceType_Video + HALDeviceVideo_VDU = &101 and looking for the value HALDeviceID_VDU_VIDC20 (= 3) in the device ID field (i.e. the first word of the device struct will be &30101)

HALDeviceAudio_AudC: This will correspond to calling OS_Hardware 4 with R0 = HALDeviceType_Audio + HALDeviceAudio_AudC = &201. Since you aren’t looking for a specific audio device (since one doesn’t exist yet for IOMD) you can (probably) just use the first device which is returned by the call.

I’ve finally got around to coding IOMD RO5 support, but am having problems.

How can I prevent the OS from actioning the IRQ’s and instead pass them to IRQ1v? Do I need to claim them via OS_ClaimDeviceVector* and then call IRQ1v manually?

EDIT: I believe the problem I’m seeing is due to HAL_Timers now intercepting T1, where previously it would be passed to IRQ1v.

* Claiming device 6 works, but relying on IRQ1v to be called when T1 triggers doesn’t. I could work around this by claiming device 6, calling IRQ1v and only passing to the OS if the game doesn’t action it.