Hi I too have started doing most of the stuffs in asm rather than going for C functions. The first thing that I am concentrating is the SYNTH function.
Bt still since i am following the LONG calculation(Q28.4) instead of Q15.1, mine is still vulnerable for timing issues. It will be gr8 help if you could send me across your version (16 bit arithmetic and Q15.1 for 55X) of MAD decoder for my reference.
Thanks in advance Balaji Shanmugam
From: "Grigory A." Ryhor@tut.by Reply-To: "Grigory A." Ryhor@tut.by To: "balaji shanmugam" balajiami@hotmail.com CC: mad-dev@lists.mars.org Subject: Re: [mad-dev] MAD library for TI-54X DSPs Date: Wed, 21 Jul 2004 09:58:50 +0900
Hi Balaji!
I have ported MAD to TI-55xx. I used Q1.15 format and 16 bits arithmetics for all calculation. As result of this is:
limited accuracy ISO/IEC 11172-3 audio decoder
according to http://www.underbit.com/resources/mpeg/audio/compliance/
Yes - synthesis step of decoding is most calculation intensive part. I've used a little different method to port MAD to TI-55xx DSP - instead of providing "arithmetics macro" for given platform I've rewrite on DSP asm all calculation intensive functions (8 or 9 ?). So I think this is a better way in case if someone need close to optimal implementation for given hardware platform. Only you need to do is to rewrite these asm functions for your platform.
I can send you my implementation of decoder. And maybe it is better to put it to MAD site? Because I've sent it several times before to other people and this question is arisen again and again :). In additional I have same style implementation of MAD for sp3R5m DSP (www.3dsp.com) this one is 32 DSP core and in this case "fully compliant" decoder is obtained.
Tuesday, July 20, 2004, 11:25:28 PM, you wrote:
bs> Hi bs> I am trying to port the MAD library for the TI-54X DSP and running into bs> tight timing issues. When analysed, I found out that the 54X DSP takes more bs> instructions to perform LONG calculations at the SYNTHESIS FILTER Bank stage bs> as it is a 16 bit processor [but with a 40 bit accumulator]. As it is bs> required to perform 72 times the DCT32 and the remaining MATRIX calculations bs> at the SYNTH stage, I like to optimize the synthesis filter bank. bs> I am not sure about using the Q28.4 format being used by MAD. Is there bs> anyway we can use the Q15.1 format for the calculations? bs> I like to know is there any hints or clues for the LONG calculations that I bs> can make use of during my 54X porting phase. Also any thought about using bs> the NORM instruction to round the final samples to 16 bit will be helpful.
bs> Regards bs> Balaji Shanmugam
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-- Best regards, Grigory mailto:Ryhor@tut.by
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