MSVC: add support for arm64 (_M_ARM64) #34
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pmisik
reviewed
Apr 29, 2020
| #define mul64x64_128(out,a,b) out.lo = ((uint64_t)(a))*(b); out.hi = __umulh(a, b); | ||
| // note: these are special purpose functions where shift is expected to be < 64 and != 0 | ||
| #define shr128_pair(out,hi,lo,shift) out = ((lo) >> shift) | ((hi) << (64 - shift)); | ||
| #define shl128_pair(out,hi,lo,shift) out = (lo) << shift; |
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@matbech are you relay sure shl128_pair is correct?
Shouldn't it be implemented as
#define shl128_pair(out,hi,lo,shift) out = ((hi) << shift) | ((lo) >> (64 - shift));
https://docs.microsoft.com/en-us/cpp/intrinsics/shiftleft128?view=vs-2019 states
Shifts a 128-bit quantity, represented as two 64-bit quantities LowPart and HighPart, to the left by a number of bits specified by Shift and returns the high 64 bits of the result.
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You are correct, both macros are incorrect.
#define shr128_pair(out,high,low,shift) out.lo = ((low) >> shift) | ((high) << (64 - shift)); out.hi = ((high) >> shift);
#define shl128_pair(out,high,low,shift) out.lo = (low) << shift; out.hi = ((high) << shift) | ((low) >> (64 - shift));
If you confirm that this works (I have no access to ARM64 at this time), I will make the changes to this PR.
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This adds support for arm64 on MSVC.