20 Mar
2019
20 Mar
'19
1:14 a.m.
nisse@lysator.liu.se (Niels Möller) writes:
- Big-endian system, no __builtin_bswap64. Here we can either use the current code, with byte accesses only. Or attempt to define byteswap without builtins and follow 2. I'd lean towards using the current code, unless there's some system where something more complicated is known to improve performance.
And another possible trick for big-endian is to do an "opposite-endian" left shift as
((x & 0x7f7f7f7f7f7f7f7f) << 1) | ((x & 0x8080808080808080) >> 15) where this bit is the carry out ^
Regards, /Niels
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