int128

问题 On my 64 bit computer the long long type has 64 bits. print(sizeof(long long)) # prints 8 I need to use 128 bit integers and luckily GCC supports these. How can I use these within Cython? The following doesn't work. Compiling foo.pyx containing just cdef __int128_t x = 0 yields $ cython foo.pyx Error compiling Cython file: ------------------------------------------------------------ ... cdef __int128_t x = 0 ^ ------------------------------------------------------------ foo.pyx:2:5: '__int128

问题 Rust has 128-bit integers, these are denoted with the data type i128 (and u128 for unsigned ints): let a: i128 = 170141183460469231731687303715884105727; How does Rust make these i128 values work on a 64-bit system; e.g. how does it do arithmetic on these? Since, as far as I know, the value cannot fit in one register of a x86-64 CPU, does the compiler somehow use 2 registers for one i128 value? Or are they instead using some kind of big integer struct to represent them? 回答1: All Rust's

来源： https://stackoverflow.com/questions/7174419/uint128-t-on-mingw-gcc

来源： https://stackoverflow.com/questions/7174419/uint128-t-on-mingw-gcc

来源： https://stackoverflow.com/questions/7174419/uint128-t-on-mingw-gcc

问题 I'm confused with the usage of 128-bit integer. Please look at the test code: uint128_t test_data = 0x00000000FFFFFFFF0101010101010101; uint64_t test_data_h = test_data >> 64; uint64_t test_data_l = test_data ; printf("test_data 0x %016llx %016llx\n", test_data_h, test_data_l); I expect the test_data_h to be 0x00000000FFFFFFFF, but the result is : test data 0x 0000000000000000 0101010101010101 Why is this? 回答1: Many compilers do not support 128 bit constants. Instead // uint128_t test_data =

问题 I'm confused with the usage of 128-bit integer. Please look at the test code: uint128_t test_data = 0x00000000FFFFFFFF0101010101010101; uint64_t test_data_h = test_data >> 64; uint64_t test_data_l = test_data ; printf("test_data 0x %016llx %016llx\n", test_data_h, test_data_l); I expect the test_data_h to be 0x00000000FFFFFFFF, but the result is : test data 0x 0000000000000000 0101010101010101 Why is this? 回答1: Many compilers do not support 128 bit constants. Instead // uint128_t test_data =

问题 I'm confused with the usage of 128-bit integer. Please look at the test code: uint128_t test_data = 0x00000000FFFFFFFF0101010101010101; uint64_t test_data_h = test_data >> 64; uint64_t test_data_l = test_data ; printf("test_data 0x %016llx %016llx\n", test_data_h, test_data_l); I expect the test_data_h to be 0x00000000FFFFFFFF, but the result is : test data 0x 0000000000000000 0101010101010101 Why is this? 回答1: Many compilers do not support 128 bit constants. Instead // uint128_t test_data =

问题 I've heard that the 128-bit integer data-types like __int128_t provided by GCC are emulated and therefore slow. However, I understand that the various SSE instruction sets (SSE, SSE2, ..., AVX) introduced at least some instructions for 128-bit registers. I don't know very much about SSE or assembly / machine code, so I was wondering if someone could explain to me whether arithmetic with __int128_t is emulated or not using modern versions of GCC. The reason I'm asking this is because I'm

问题 I've heard that the 128-bit integer data-types like __int128_t provided by GCC are emulated and therefore slow. However, I understand that the various SSE instruction sets (SSE, SSE2, ..., AVX) introduced at least some instructions for 128-bit registers. I don't know very much about SSE or assembly / machine code, so I was wondering if someone could explain to me whether arithmetic with __int128_t is emulated or not using modern versions of GCC. The reason I'm asking this is because I'm