Intel 253668-032US Benutzerhandbuch

Vol. 3   8-59

MULTIPLE-PROCESSOR MANAGEMENT

// Returns the mask bit width of a bit field from the maximum count that bit field can represent.
// This algorithm does not assume ‘address size’ to have a value equal to power of 2.
// Address size for SMT_ID can be calculated from MaxLPIDsPerPackage()/MaxCoreIDsPerPackage()
// Then use the routine below to derive the corresponding width of SMT extraction bitmask
// Address size for CORE_ID is MaxCoreIDsPerPackage(), 
// Derive the bitwidth for CORE extraction mask similarly

unsigned FindMaskWidth(Unsigned Max_Count)
{unsigned int mask_width, cnt = Max_Count;

__asm {

mov eax, cnt
mov ecx, 0
mov mask_width, ecx
dec eax
bsr cx, ax
jz next
inc cx
mov  mask_width, ecx
next:  
mov eax, mask_width

}

return mask_width;

}

// The routine below can extract SMT_ID, CORE_ID, and PACKAGE_ID respectively from the init 

APIC_ID
// To extract SMT_ID, MaxSubIDvalue is set to the address size of SMT_ID, Shift_Count = 0
// To extract CORE_ID, MaxSubIDvalue is the address size of CORE_ID, Shift_Count is width of SMT 

extraction bitmask.
// Returns the value of the sub ID, this is not a zero-based value 

Unsigned char GetSubID(unsigned char Full_ID, unsigned char MaxSubIDvalue, unsigned char 

Shift_Count)
{

MaskWidth = FindMaskWidth(MaxSubIDValue);
MaskBits = ((uchar) (0xff << Shift_Count)) ^ ((uchar) (0xff << Shift_Count + MaskWidth)) ;
SubID = Full_ID & MaskBits;
Return SubID;

}