Roland> It's odd that you saw the expession end up as 0. It seems
Roland> that on every system I have, 1ull << 64 is 0, and 0 - 1 ==
Roland> -1 == 0xffffffffffffffff. So although it isn't correct C,
Roland> it should work.
Oh, I see. A constant left shift of 64 is evaluated to 0 at compile
time. But a variable left shift that ends up as 64 indeed gives the
wrong answer. So you're right, packer will get the wrong answer.
I think this should fix it properly:
--- core/packer.c (revision 2665)
+++ core/packer.c (working copy)
@@ -96,7 +96,7 @@ void ib_pack(const struct ib_field
else
val = 0;
- mask = cpu_to_be64(((1ull << desc[i].size_bits) - 1) <<
shift);
+ mask = cpu_to_be64((~0ull >> (64 - desc[i].size_bits))
<< shift);
addr = (__be64 *) ((__be32 *) buf +
desc[i].offset_words);
*addr = (*addr & ~mask) | (cpu_to_be64(val) & mask);
} else {
@@ -176,7 +176,7 @@ void ib_unpack(const struct ib_field
__be64 *addr;
shift = 64 - desc[i].offset_bits - desc[i].size_bits;
- mask = ((1ull << desc[i].size_bits) - 1) << shift;
+ mask = (~0ull >> (64 - desc[i].size_bits)) << shift;
addr = (__be64 *) buf + desc[i].offset_words;
val = (be64_to_cpup(addr) & mask) >> shift;
value_write(desc[i].struct_offset_bytes,
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