Looks good to me though I barely understand the code there... I guess ideally you'd generate code which actually clamps to the max int value representable instead, but that probably would get even more messy (something like: val = MAX(src[0], -2147483648.0f) if (src[0] >= 2147483648.0f) val = 2147483647)
Reviewed-by: Roland Scheidegger <srol...@vmware.com> Am 07.11.2014 um 22:25 schrieb jfons...@vmware.com: > From: José Fonseca <jfons...@vmware.com> > > Use clamping constants that guarantee no integer overflows. > > As spotted by Chris Forbes. > > This causes the code to change as: > > - value |= (uint32_t)CLAMP(src[0], 0.0f, 4294967295.0f); > + value |= (uint32_t)CLAMP(src[0], 0.0f, 4294967040.0f); > > - value |= (uint32_t)((int32_t)CLAMP(src[0], -2147483648.0f, > 2147483647.0f)); > + value |= (uint32_t)((int32_t)CLAMP(src[0], -2147483648.0f, > 2147483520.0f)); > --- > src/gallium/auxiliary/util/u_format_pack.py | 27 +++++++++++++++++++++++++++ > 1 file changed, 27 insertions(+) > > diff --git a/src/gallium/auxiliary/util/u_format_pack.py > b/src/gallium/auxiliary/util/u_format_pack.py > index 90f348e..d5138cc 100644 > --- a/src/gallium/auxiliary/util/u_format_pack.py > +++ b/src/gallium/auxiliary/util/u_format_pack.py > @@ -207,9 +207,36 @@ def get_one_shift(type): > assert False > > > +def truncate_mantissa(x, bits): > + '''Truncate an integer so it can be represented exactly with a floating > + point mantissa''' > + > + assert isinstance(x, (int, long)) > + > + s = 1 > + if x < 0: > + s = -1 > + x = -x > + > + # We can represent integers up to mantissa + 1 bits exactly > + mask = (1 << (bits + 1)) - 1 > + > + # Slide the mask until the MSB matches > + shift = 0 > + while (x >> shift) & ~mask: > + shift += 1 > + > + x &= mask << shift > + x *= s > + return x > + > + > def value_to_native(type, value): > '''Get the value of unity for this type.''' > if type.type == FLOAT: > + if type.size <= 32 \ > + and isinstance(value, (int, long)): > + return truncate_mantissa(value, 23) > return value > if type.type == FIXED: > return int(value * (1 << (type.size/2))) > _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
