apic.h

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/* Copyright (C) 2022 Wildfire Games.
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#ifndef INCLUDED_X86_X64_APIC
#define INCLUDED_X86_X64_APIC
 
typedef u8 ApicId;  // not necessarily contiguous values
 
/**
 * @return APIC ID of the currently executing processor or zero if the
 * platform does not have an xAPIC (i.e. 7th generation x86 or below).
 *
 * rationale: the alternative of accessing the APIC mmio registers is not
 * feasible. We also don't want to interfere with the OS's constant use of
 * the APIC registers.
 **/
ApicId GetApicId();
 
// if this returns false, apicId = contiguousId = processor.
// otherwise, there are unspecified but bijective mappings between
// apicId<->contiguousId and apicId<->processor.
bool AreApicIdsReliable();
 
// we may get the apicId of a processor we don't have access to.
bool IsProcessorKnown(ApicId apicId);
 
size_t ProcessorFromApicId(ApicId apicId);
size_t ContiguousIdFromApicId(ApicId apicId);
 
ApicId ApicIdFromProcessor(size_t contiguousId);
ApicId ApicIdFromContiguousId(size_t contiguousId);
 
#endif  // #ifndef INCLUDED_X86_X64_APIC