41 lines
1.0 KiB
C++
41 lines
1.0 KiB
C++
#ifdef _MSC_VER
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#include <intrin.h>
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#pragma intrinsic(_umul128)
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#endif
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#include "common/uint128.h"
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namespace Common {
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u128 Multiply64Into128(u64 a, u64 b) {
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#ifdef _MSC_VER
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u128 result;
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result[0] = _umul128(a, b, &result[1]);
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#else
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unsigned __int128 tmp = a;
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tmp *= b;
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u128 result;
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std::memcpy(&result, &tmp, sizeof(u128));
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#endif
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return result;
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}
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std::pair<u64, u64> Divide128On64(u128 dividend, u64 divisor) {
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u64 remainder = dividend[0] % divisor;
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u64 accum = dividend[0] / divisor;
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if (dividend[1] == 0)
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return {accum, remainder};
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// We ignore dividend[1] / divisor as that overflows
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u64 first_segment = (dividend[1] % divisor) << 32;
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accum += (first_segment / divisor) << 32;
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u64 second_segment = (first_segment % divisor) << 32;
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accum += (second_segment / divisor);
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remainder += second_segment % divisor;
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if (remainder >= divisor) {
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accum++;
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remainder -= divisor;
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}
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return {accum, remainder};
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}
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} // namespace Common
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