Luigi Castelli wrote:
>I multiply big float values and - after being appropriately cast -
>assign them to the above variable.
>
>Example:
>
>int value = (int)(32768. * 65536.) // (and bigger)
>
>I just so happens that when the result of the multiplication exceed the
>size of the value that a 32 bit int type variable is able to represent
>the value is clipped to -2147483648. I have noticed that the cast
>(either explicit or implicit) is what causes the value to be clipped,
>because if I cast to a bigger value (i.e. 64 bit) then the value is
>wrapped until the 64 bit maximum is reached. Then the value is clipped
>again.
>
>In any case for the algorithm I am developing I would like the int
>value to be wrapped, not clipped. I would like after reaching the
>value's maximum limit to go back and start again from its minimum.
This seems like a simple answer: don't use float arithmetic.
Only use operands that are 32-bit ints, not floats.
You might also look into the Intel-specific behavior of casting floats to
ints (overrange type-narrowing conversions). If CodeWarrior-compiled code
wrapped around, it may be a side-effect of the CPU arch (PPC), and not at
all related to CW vs. Xcode. As I vaguely recall, these kinds of
conversions are unspecified by the C spec, but you really should check a
spec, or just use ints.
-- GG
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