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controller: fixes int overflow with properties that span +-INT_MAX

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When the range for a property is defined as -INT_MAX-1 .. INT_MAX, like
the xpos in a videomixer the following expression in the macro
definitions of convert_g_value_to_##type (and the equivalent in
convert_value_to_##type)

v = pspec->minimum + (g##type) ROUNDING_OP ((pspec->maximum - pspec->minimum) * s);

are converted to:

v = -2147483648 + (g##type) ROUNDING_OP ((2147483647 - -2147483648) * s);

(2147483647 - -2147483648) overflows to -1 and the net result is:

v = -2147483648 + (g##type) ROUNDING_OP (-1 * s);

so v only takes the values -2147483648 for s == 0 and 2147483647
for s == 1.

Rewriting the expression as minimum*(1-s) + maximum*s gives the correct
result in this case.

https://bugzilla.gnome.org//show_bug.cgi?id=705630
This commit is contained in:
Adrian Pardini 2013-08-07 14:17:28 -03:00 committed by Sebastian Dröge
parent 6c11da18a5
commit d4f6c8e0e6
1 changed files with 2 additions and 2 deletions
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4
libs/gst/controller/gstdirectcontrolbinding.c
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@ -85,7 +85,7 @@ convert_g_value_to_##type (GstDirectControlBinding *self, gdouble s, GValue *d)
g##type v; \
\
s = CLAMP (s, 0.0, 1.0); \
v = pspec->minimum + (g##type) ROUNDING_OP ((pspec->maximum - pspec->minimum) * s); \
v = (g##type) ROUNDING_OP (pspec->minimum * (1-s)) + (g##type) ROUNDING_OP (pspec->maximum * s); \
g_value_set_##type (d, v); \
} \
\
@ -96,7 +96,7 @@ convert_value_to_##type (GstDirectControlBinding *self, gdouble s, gpointer d_)
g##type *d = (g##type *)d_; \
\
s = CLAMP (s, 0.0, 1.0); \
*d = pspec->minimum + (g##type) ROUNDING_OP ((pspec->maximum - pspec->minimum) * s); \
*d = (g##type) ROUNDING_OP (pspec->minimum * (1-s)) + (g##type) ROUNDING_OP (pspec->maximum * s); \
}