Suppose that I want to create a compile time constructed bit count lookup table for 64bit integers. The only way I know to do this is the following code:
#define B4(n) n, n + 1, n + 1, n + 2
#define B6(n) B4(n), B4(n + 1), B4(n + 1), B4(n + 2)
#define B8(n) B6(n), B6(n + 1), B6(n + 1), B6(n + 2)
#define B10(n) B8(n), B8(n + 1), B8(n + 1), B8(n + 2)
#define B12(n) B10(n), B10(n + 1), B10(n + 1), B10(n + 2)
#define B14(n) B12(n), B12(n + 1), B12(n + 1), B12(n + 2)
#define B16(n) B14(n), B14(n + 1), B14(n + 1), B14(n + 2)
#define COUNT_BITS B16(0), B16(1), B16(1), B16(2)
unsigned int lookup[65536] = { COUNT_BITS };
Is there a modern (C++11/14) way to obtain the same result?
Aucun commentaire:
Enregistrer un commentaire