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Overflow not detected

Note: This was originally posted on 6th September 2010 at http://forums.arm.com

Hi all,
I'm quite new in arm assembly programming, and I went into a odd behaviour.

I'm going to multiply two numbers with the mul instruction;
the code is:

ldr      r0, =0x26000000
ldr      r1, =0x10
muls r2, r1, r0
bvs    somewhere

The result from the the mul istruction is (0x2600 0000 * 0x10 = ) 0x2 6000 0000.
Now, i expected the V bit going to one, but none of the CPSR bits is setted.
Why is happening this? How can I detect overflow in such operations?
I'm using the gnuarm compiler, and working with 32-bit registers.

Thanks in advance,
Stefano.

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Scott Douglass over 12 years ago

Note: This was originally posted on 7th September 2010 at http://forums.arm.com

Why is happening this? How can I detect overflow in such operations?
I'm using the gnuarm compiler, and working with 32-bit registers.

There's a blog entry "next door" that discusses this [url="http://blogs.arm.com/software-enablement/detecting-overflow-from-mul/"]http://blogs.arm.com/software-enablement/d...rflow-from-mul/[/url].
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Scott Douglass over 12 years ago

Note: This was originally posted on 7th September 2010 at http://forums.arm.com

Why is happening this? How can I detect overflow in such operations?
I'm using the gnuarm compiler, and working with 32-bit registers.

There's a blog entry "next door" that discusses this [url="http://blogs.arm.com/software-enablement/detecting-overflow-from-mul/"]http://blogs.arm.com/software-enablement/d...rflow-from-mul/[/url].
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