accessing Global Tables

Marcello Gagliardi

Hi,

I am building an ELF dll on the C67x+ and I am trying to implement a lookup table for a fast single precision (float) log10 implementation.

I cannot use the fastRTS libs due to environment set up upon which I don't have control.

I am using CCS v4.2.5 + CGT7.0.5 and I am not allowed to upgrade to any other version as it is not supported yet.

The problem I am seeing is that the values picked up from the global table in the DSP algorithm are rubbish.

Since it should be fairly straightforward to create a global table, I am not sure what is going wrong.

Could you please tell me the correct procedure to access a global table from the main DSP algorithm?

thanks

over 13 years ago

George Mock over 13 years ago

TI__Guru**** 253380 points

Is this C code, or assembly code? -George

Marcello Gagliardi over 13 years ago in reply to George Mock

Intellectual 295 points

Hi George,

this is C code I am talking about.

Thus I declare :

extern float GlobalLogTable[1<<PRECISION]; //could be from 11 up to 15 bits of precision

and pick it up in the main DSP algorithm:

val = GlobalLogTable[x]; //lookup precomputed value

Nice and simple.

George Mock over 13 years ago in reply to Marcello Gagliardi

TI__Guru**** 253380 points

The linker map file includes a symbol table that shows the address of GlobalLogTable. Does this address make sense in your system? Might there be some HW based reason why initializing or reading that memory would fail?

Thanks and regards,

-George

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accessing Global Tables