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IsWiiElf: Optimise inner loop. 

Instead of swaping each word of the elf code section(s) looking
for a match to our pattern, we swap the pattern just once (at
compile  time) and test against our swapped pattern.
This commit is contained in:
Scott Mansell 2014-11-01 23:15:58 +13:00
parent 2bf052d8b9
commit b7d4ff679a
1 changed files with 6 additions and 7 deletions
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13
Source/Core/Core/Boot/Boot_ELF.cpp
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@ -29,21 +29,20 @@ bool CBoot::IsElfWii(const std::string& filename)
// Likely to have some false positives/negatives, patches implementing a // Likely to have some false positives/negatives, patches implementing a
// better heuristic are welcome. // better heuristic are welcome.
u32 HID4_pattern = 0x7c13fba6; // Swap these once, instead of swapping every word in the file.
u32 HID4_mask = 0xfc1fffff; u32 HID4_pattern = Common::swap32(0x7c13fba6);
u32 HID4_mask = Common::swap32(0xfc1fffff);
ElfReader reader(elf.get()); ElfReader reader(elf.get());
for (int i = 0; i < reader.GetNumSections(); ++i) for (int i = 0; i < reader.GetNumSections(); ++i)
{ {
if (reader.IsCodeSection(i)) if (reader.IsCodeSection(i))
{ {
for (unsigned int j = 0; j < reader.GetSectionSize(i) / sizeof (u32); ++j) u32* code = (u32*)reader.GetSectionDataPtr(i);
for (u32 j = 0; j < reader.GetSectionSize(i) / sizeof(u32); ++j)
{ {
u32 word = Common::swap32(((u32*)reader.GetSectionDataPtr(i))[j]); if ((code[j] & HID4_mask) == HID4_pattern)
if ((word & HID4_mask) == HID4_pattern)
{
return true; return true;
}
} }
} }
} }