According to Intel's definition of a x86 16-bit Word, a Quad Word refers a 64-bit word.
long long or long
Microsoft 64-bit C-compiler long is still 32-bit Double Word, while 64-bit GCC uses 64-bit Quad Words as longs. Other compiler require "long long" for 64-bit types.
Quad Words stored in memory should be stored at byte addresses divisible by eight. Otherwise at runtime it will cause a miss-alignment exception on some processors, or a huge penalty on others.
Table of Contents
According to Intel's definition of a x86 16-bit Word, a Quad Word refers a 64-bit word.
long long or long
Microsoft 64-bit C-compiler long is still 32-bit Double Word, while 64-bit GCC uses 64-bit Quad Words as longs. Other compiler require "long long" for 64-bit types.Bitboards
Quad words are used as bitboard datatype:Ranges
Alignment
Quad Words stored in memory should be stored at byte addresses divisible by eight. Otherwise at runtime it will cause a miss-alignment exception on some processors, or a huge penalty on others.Endianness
Main article: Endianness.Litte-endian layout
The little-endian memory layout, as typical for Intel cpus.For instance the quad word integer 0x0102030405060708
Big-endian layout
The big-endian memory layout, as typical for Motorola cpus.For instance the quad word integer 0x0102030405060708
See also
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