The R Project SVN R

/* Mingw.org headers are missing this */

typedef enum _LOGICAL_PROCESSOR_RELATIONSHIP {
    RelationProcessorCore,
    RelationNumaNode,
    RelationCache,
    RelationProcessorPackage,
    RelationGroup,
    RelationAll=0xffff
} LOGICAL_PROCESSOR_RELATIONSHIP;

typedef enum _PROCESSOR_CACHE_TYPE {
    CacheUnified,CacheInstruction,CacheData,CacheTrace
} PROCESSOR_CACHE_TYPE;

typedef struct _CACHE_DESCRIPTOR {
    BYTE Level;
    BYTE Associativity;
    WORD LineSize;
    DWORD Size;
    PROCESSOR_CACHE_TYPE Type;
} CACHE_DESCRIPTOR,*PCACHE_DESCRIPTOR;

typedef struct _SYSTEM_LOGICAL_PROCESSOR_INFORMATION {
    ULONG_PTR ProcessorMask;
    LOGICAL_PROCESSOR_RELATIONSHIP Relationship;
    union {
    struct {
        BYTE Flags;
    } ProcessorCore;
    struct {
        DWORD NodeNumber;
    } NumaNode;
    CACHE_DESCRIPTOR Cache;
    ULONGLONG Reserved[2];
    };
} SYSTEM_LOGICAL_PROCESSOR_INFORMATION,*PSYSTEM_LOGICAL_PROCESSOR_INFORMATION;

WINBASEAPI WINBOOL WINAPI 
GetLogicalProcessorInformation(PSYSTEM_LOGICAL_PROCESSOR_INFORMATION Buffer,
                   PDWORD ReturnedLength);