| Message ID | fbef0a4b03aec3dd86034cbcad3d1a4e8878b7b9.1463093051.git.alistair.francis@xilinx.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 12 May 2016 at 23:45, Alistair Francis <alistair.francis@xilinx.com> wrote: > Add a macro that creates a 64bit value which has length number of ones > shifted acrros by the value of shift. "across" > > Signed-off-by: Alistair Francis <alistair.francis@xilinx.com> > Reviewed-by: Alex Bennée <alex.bennee@linaro.org> > --- > V5: > - Re-write to a 64-bit mask instead of ONES() > - Re-order this patch in the series > > include/qemu/bitops.h | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/include/qemu/bitops.h b/include/qemu/bitops.h > index 755fdd1..3c45791 100644 > --- a/include/qemu/bitops.h > +++ b/include/qemu/bitops.h > @@ -24,6 +24,9 @@ > #define BIT_WORD(nr) ((nr) / BITS_PER_LONG) > #define BITS_TO_LONGS(nr) DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(long)) > > +#define MAKE_64BIT_MASK(shift, length) \ > + (((1ull << (length)) - 1) << shift) > + This is undefined behaviour for a 64-bit length. The expression we use in deposit64() to create a mask is ((~0ULL >> (64 - length)) << start) thanks -- PMM
On Thu, Jun 9, 2016 at 11:46 AM, Peter Maydell <peter.maydell@linaro.org> wrote: > On 12 May 2016 at 23:45, Alistair Francis <alistair.francis@xilinx.com> wrote: >> Add a macro that creates a 64bit value which has length number of ones >> shifted acrros by the value of shift. > > "across" > >> >> Signed-off-by: Alistair Francis <alistair.francis@xilinx.com> >> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> >> --- >> V5: >> - Re-write to a 64-bit mask instead of ONES() >> - Re-order this patch in the series >> >> include/qemu/bitops.h | 3 +++ >> 1 file changed, 3 insertions(+) >> >> diff --git a/include/qemu/bitops.h b/include/qemu/bitops.h >> index 755fdd1..3c45791 100644 >> --- a/include/qemu/bitops.h >> +++ b/include/qemu/bitops.h >> @@ -24,6 +24,9 @@ >> #define BIT_WORD(nr) ((nr) / BITS_PER_LONG) >> #define BITS_TO_LONGS(nr) DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(long)) >> >> +#define MAKE_64BIT_MASK(shift, length) \ >> + (((1ull << (length)) - 1) << shift) >> + > > This is undefined behaviour for a 64-bit length. The expression > we use in deposit64() to create a mask is > ((~0ULL >> (64 - length)) << start) Fixed both. Thanks, Alistair > > thanks > -- PMM >
diff --git a/include/qemu/bitops.h b/include/qemu/bitops.h index 755fdd1..3c45791 100644 --- a/include/qemu/bitops.h +++ b/include/qemu/bitops.h @@ -24,6 +24,9 @@ #define BIT_WORD(nr) ((nr) / BITS_PER_LONG) #define BITS_TO_LONGS(nr) DIV_ROUND_UP(nr, BITS_PER_BYTE * sizeof(long)) +#define MAKE_64BIT_MASK(shift, length) \ + (((1ull << (length)) - 1) << shift) + /** * set_bit - Set a bit in memory * @nr: the bit to set