64 bit assignment on a 32 bit platform

[kum <a.kumaresh@xxxxxxxxx>]

Hi,

UINT64 a64; // UINT64 has been typedefed as long long unsigned int
UINT32 a32, b32;
a32 = x; // some value
b32 = y; // some value

a64 = a32 * b32;
a64 += a32 + b32;

Is it necessary to type-cast both a32 and b32 to yield correct 64 bit
results? Without casting, I find that addition (even if the result
overflows) works while the multiplication does not. Is there a
compiler option to make this work without casting? I am using gcc
4.1.1 on an xscale platform.

Thank you all,
kumaresh