AM2434: FPU exceptions not triggered

Luís Fernando Arcaro

Part Number: AM2434

Tool/software:

I have attempted enabling FPU traps using this code:

vmrs r0, fpscr
movw r1, #0x9F00
movt r1, #0x03C0
bic r0, r0, r1
movw r1, #0x0700
movt r1, #0x0100
orr r0, r0, r1
vmsr fpscr, r0

However, the value of FPSCR does not change accordingly and no traps are triggered when FPU exceptions (e.g. division by zero) are produced.

I have already confirmed that in my division by zero test the operator loading and division instructions are being executed, but Inf is produced as output and no exception is being triggered.

How should I proceed to enable FPU traps?

Regards,
Luís

7 months ago

0 Tushar Thakur 7 months ago

TI__Guru 50068 points

Hi Luis,

Thanks for your patience.

Luís Fernando Arcaro said:
However, the value of FPSCR does not change accordingly and no traps are triggered when FPU exceptions (e.g. division by zero) are produced.

Please try enabling the -ffast-math flag in the CCS project. To enable -ffast-math flag, open project properties.

Navigate to Tools -> Arm Compiler -> Optimizations, check the -ffast-math option to enable it.

Please refer below image.

Regards,

Tushar

0 Luís Fernando Arcaro 7 months ago

Prodigy 20 points

I am not using CCS, actually. Could you please detail the effect of this option and how it is expected to affect the generation of exceptions?

0 Tushar Thakur 7 months ago in reply to Luís Fernando Arcaro

TI__Guru 50068 points

Hi,

You can add the flag inside the makefile of the example.

Please refer below image.

Regards,

Tushar

0 Luís Fernando Arcaro 7 months ago in reply to Tushar Thakur

Prodigy 20 points

I am not using the CCS-provided compiler as well, actually. The compiler I am using does not have this exact option, so I need to know the function of the flag and the role it could play in raising exceptions.

0 Tushar Thakur 7 months ago in reply to Luís Fernando Arcaro

TI__Guru 50068 points

Hi Luis,

TI will be not be able to help you with other compiler issues than the one recommended on official documentation of MCU+SDK.

I can only give you details about the -ffast-math flag which tells the compiler to do the aggressive FPU arithmetic operations by assumptions about floating math operations.

For details, please refer cmdoption-ffast-math.

Closing the thread.

Regards,

Tushar

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AM2434: FPU exceptions not triggered