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)))
--
1.9.1
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