Can anyone help explain what does
#define SPLAT(p) (*(p) * (~0UL / 255))
unsigned long val = SPLAT(page);
Assume that a
long is 32 bits. The ~0UL is a bit pattern of all ones i.e. 0xffffffff. Now divide by 255 or 0xff giving 0x01010101.
Multiply this with an 8 bit quantity and you will get the same byte 4 times; e.g 0x5a * 0x01010101 = 0x5a5a5a5a.