TMDSDSK6713: WHat is MAC, distinguish MAC and MACs

minh nguyen van

Part Number: TMDSDSK6713

Hi , when I see a document about DSK 6713 and know that :" Even using natual C,the C6000 architecture can perform 2 to 4 MACs per cycle".

I wonder about : What is MAC in this document

For example : I compute : vecto a[8] * vecto b[8]

int sum =0;

for (int i = 0 ; i<7 ;i++)

{

Sum = sum +a(i)*b(i);

}

Can you tell me how many MACs will use?

Thanks so much!

over 6 years ago

0 Yordan Kovachev over 6 years ago

TI__Guru**** 161600 points

Hi,

This is multiply-accumulate operation. This is a common step that computes the product of two numbers and adds that product to an accumulator, you can use the publicly available information to gain some insights on what is this & how it works.

Best Regards,
Yordan

0 minh nguyen van over 6 years ago in reply to Yordan Kovachev

Prodigy 240 points

Thanks for your replies,
;
I wonder about :
In my example : I compute : vecto a[8] * vecto b[8]
int sum =0;
for (int i = 0 ; i<8 ;i++)
{
sum = sum +a(i)*b(i);
}
WIll DSP use 8 MACs unit ?

I have another question :
I have bought TCI6638K2K,
I want to estimate about my company system.
with parameter : 38.4 GMacs/Core for Fixed Point @ 1.2 GHz.
for simply, i suppose : 1 GHz
In one core, 1 cycle = 1 ns.
=> 38.4GMACs / 1 Giga cycles
=> 3.84 MACs /cycles.
Is this correct ?
Thanks so much .

0 RandyP over 6 years ago in reply to minh nguyen van

TI__Guru* 84110 points

Minh,

You started this thread referencing the C6713, and now you are using the TCI6638K2K. These devices are very far apart from each other in performance. The TCI6638K2K is generally not supported on the public forum but it is sold and supported for a limited market for limited applications. Is your company on that list and do you have direct support team at TI?

Your code syntax is incorrect in your summation line, but yes that code would perform 8 MAC operations, not 8 MAC units. Since you are asking about MACs, your knowledge is at the basic level and you will want to look through the training material that TI provides, the documentation on the C66x CPU and Instruction Set, and look for online training on DSP methods.

Your math for MACs / cycle is wrong in two ways: 1) you must divide by 1.2 to get the right answer, not 1.0 to be simple, and 2) you calculated 38.4/1 and came up with 3.84/cycle - somehow including an extra divide-by-10.

These numbers are only for comparison purposes when shopping for a processor. These are maximum theoretical figures that will be a part of your final result but not the primary feature.

What are you trying to do with either the C6713 or the TCI6638K2K?

Please search TI.com for training material on the processor that you are working with.

Regards,
RandyP

0 minh nguyen van over 6 years ago in reply to RandyP

Prodigy 240 points

Thanks so much !

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TMDSDSK6713: WHat is MAC, distinguish MAC and MACs