[U-Boot-Users] [Q] memtest doubt

[Guennadi Liakhovetski]

Hi all,

looking through the common/cmd_mem.c::do_mem_mtest() function, I couldn't 
understand the following place:

		addr_mask = ((ulong)end - (ulong)start)/sizeof(vu_long);
...
		for (offset = 1; (offset & addr_mask) != 0; offset <<= 1) {
			start[offset] = pattern;
		}

why (offset & addr_mask) != 0 and not just offset < addr_mask? Suppose

	end = 0xbf;
	start = 0;

	addr_mask = 0x2f;

The loop will iterate over offset = 1, 2, 4, 8, and on 0x10 it will abort 
and 0x10 and 0x20 will stay untested. Whereas if we just had "offset < 
addr_mask" it would just function correctly, wouldn't it? Yes, I do 
realise, that it is at least unusual to set the end address to anything 
other than start address + ((1 << x) - 1), but still.

Thanks
Guennadi
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Guennadi Liakhovetski