DM8148 - IPIPE Gamma tables alignment

weber de souza calixto

Hi,

Using IPNC RDK 3.8 as basecode.

"TMS320DM814x Imaging Subsystem (ISS) User's Guide" describes that each gamma table component has 20 bits.

However it does not mention the alignment that each table must have.

It should be 24 or 32 bits aligned? For 32 bits alignment each table would have a total size 512x4 bytes, and for 24 bis alignment each table would have a total size of 512x3 bytes.

Or is the table packed? In this case each table would have a total size of 512x20 bits = 10240 bytes.

I do not know what is the proper way to write into the gamma tables memory. Please clarify.

Regards,

Weber

over 10 years ago

0 Margarita Gashova over 10 years ago

TI__Guru* 80190 points

Hello,

I will notify the IPNC team for help.

Margarita

0 weber de souza calixto over 10 years ago in reply to Margarita Gashova

Expert 1700 points

I've already figured it out.

Thanks.

0 tbari over 9 years ago in reply to weber de souza calixto

Prodigy 210 points

Hi!

Could you share the answer then? Thanks in advance,
-- Tamas

0 weber de souza calixto over 9 years ago in reply to tbari

Expert 1700 points

Tamas,

(In not receiving email alerts dunno why).

If you are using IPNC_RDK (3.8) there is a function "ipipe_config_gamma" that already packs the data. Inside the struct passed as argument you must provide a pointer to a table wich each gamma point stored in a 16 byte value.

If not, you can pack the 10 LSB of every 2 gamma points into a 4 byte variable and write into their respective gamma table adress.

Regards,

Weber Calixto

0 tbari over 9 years ago in reply to weber de souza calixto

Prodigy 210 points

Hello!

I figured it out since then, but thank you anyways! I will write down how I do it, maybe it will help someone else:
I use the same gamma table for all three channels for now (RGB), so I only do one calculation.

UInt32 mPackedGamma[ 512 ];
UInt32 calculatedOffset = 0;
int32_t calculatedSlope = 0;
for( int i = 0; i<512; ++i ){

   // ... calculate offset and slope for i

    mPackedGamma[ idx ] = ( calculatedOffset << 10 ) | ( 0x3FF & (calculatedSlope) );

}

Then I memcpy the mPackedGamma array to the hardware address for gamma.

-- Tamás

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DM8148 - IPIPE Gamma tables alignment