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Replace MMU mask tests with dedicated function. 

The efficient function (that is nearly the same as
https://graphics.stanford.edu/~seander/bithacks.html#DetermineIfPowerOf2)
replaces one loop based instance (which also reused the xx variable
afterwards, whereas it should have used htabmask instead) and one
instance using the population count a.k.a. Hamming weigth.
This commit is contained in:
Niels Boehm 2017-06-22 13:04:00 +02:00
parent df82adca43
commit 56158ca176
1 changed files with 5 additions and 14 deletions
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19
Source/Core/Core/PowerPC/MMU.cpp
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@ -7,7 +7,7 @@
#include <string>
#include "Common/Atomic.h"
#include "Common/BitSet.h"
#include "Common/BitUtils.h"
#include "Common/CommonTypes.h"
#include "Core/ConfigManager.h"
@ -947,26 +947,17 @@ static void GenerateISIException(u32 _EffectiveAddress)
void SDRUpdated()
{
u32 htabmask = SDR1_HTABMASK(PowerPC::ppcState.spr[SPR_SDR]);
u32 x = 1;
u32 xx = 0;
int n = 0;
while ((htabmask & x) && (n < 9))
{
n++;
xx |= x;
x <<= 1;
}
if (htabmask & ~xx)
if (!Common::IsValidLowMask(htabmask))
{
return;
}
u32 htaborg = SDR1_HTABORG(PowerPC::ppcState.spr[SPR_SDR]);
if (htaborg & xx)
if (htaborg & htabmask)
{
return;
}
PowerPC::ppcState.pagetable_base = htaborg << 16;
PowerPC::ppcState.pagetable_hashmask = ((xx << 10) | 0x3ff);
PowerPC::ppcState.pagetable_hashmask = ((htabmask << 10) | 0x3ff);
}
enum TLBLookupResult
@ -1175,7 +1166,7 @@ static void UpdateBATs(BatTable& bat_table, u32 base_spr)
// implemented this way for invalid BATs as well.
WARN_LOG(POWERPC, "Bad BAT setup: BPRN overlaps BL");
}
if (CountSetBits((u32)(batu.BL + 1)) != 1)
if (!Common::IsValidLowMask((u32)batu.BL))
{
// With a valid BAT, the simplest way of masking is
// (input & ~BL_mask) for matching and (input & BL_mask) for