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Discussion Groups | TMS320C54x | Real FFT
Technical discussions about the TI C54x DSPs (including the c5401, c5402, c5402a, c5404, c5407, c5409, c5409a, c5410, c5410a, c5416, c5420, c5421, c5441, c549, c5470 and c5471).
Re: Real FFT - Eris Ristemena - Oct 30 8:34:00 1999
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anytime ... :) -----Original Message----- From: Andrew B <> To: <> Date: Saturday, October 30, 1999 3:29 PM Subject: [c54x] Re: Real FFT >I have just found out the answer.... > >Apparently, > >B = A - *AR2+<<16 > >has the same meaning with > >B = *AR2+<<16 - A >thanks anyway................ |
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Real FFT - Andrew B - Oct 30 23:29:00 1999
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I have a problem with 'C542 DSKplus' Real FFT example especially in phase 2 (N complex FFT) during stage 3 thru (LOGN-1) computation. Here is the code: ----------------- group: data(BRC) = MMR(AR6) ; # of butterflies in each group dblockrepeat(bend-1) T = *AR4 ; T := WR A = T * *AR3+ ; A := QR*WR || AR3->QI ********************************************************************************\ ************** *As what the comment says: *A contains QR*WR ********************************************************************************\ ************** A = rnd(A + *AR5+0% * *AR3-), T = *AR5+0% ; A := QR*WR+QI*WI || AR3->QR ********************************************************************************\ ************** *A contains QR*WR+QI*WI ********************************************************************************\ ************** B = A + *AR2<<16 ; B := (QR*WR+QI*WI)+PR ********************************************************************************\ ************** *AR2 points to PR *B contains (QR*WR+QI*WI) + PR ********************************************************************************\ ************** *AR2 = HI(B)<<ASM ; PR':=((QR*WR+QI*WI)+PR)/2 ********************************************************************************\ ************** *PR' = (QR*WR+QI*WI) + PR ********************************************************************************\ ************** || B = A - *AR2+<<16 ; B := PR-(QR*WR+QI*WI) || AR2->PI ********************************************************************************\ ************** *Here is the problem: *---------------------------------- *B contains (QR*WR+QI*WI)-PR *where B should be PR-(QR*WR+QI*WI) ********************************************************************************\ ************** *AR3 = HI(B)<<ASM ; QR':= (PR-(QR*WR+QI*WI))/2 || A = T * *AR3+ ; A := QR*WI [T=WI] || AR3->QI A = rnd(A - *AR3 * *AR4+0%), T = *AR3 ; A := QR*WI-QI*WR B = A + *AR2<<16 ; B := (QR*WI-QI*WR)+PI *AR3+ = HI(B)<<ASM ; QI':=((QR*WI-QI*WR)+PI)/2 || AR3->QR || B = A - *AR2<<16 ; B := PI-(QR*WI-QI*WR) ********************************************************************************\ ************** *Here is another problem: *---------------------------------- *B contains (QR*WI-QI*WR)-PI *where B should be PI-(QR*WI-QI*WR) ********************************************************************************\ ************** T = *AR4 *AR2+ = HI(B)<<ASM ; PI':= (PI-(QR*WI-QI*WR))/2 || AR2->PR || A = T * *AR3+ ; A := QR*WR || AR3->QI bend: Can anyone help me? sincerely, Andrew ______________________________________________________ |
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Re: Real FFT - Andrew B - Oct 31 1:26:00 1999
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I have just found out the answer.... Apparently, B = A - *AR2+<<16 has the same meaning with B = *AR2+<<16 - A thanks anyway................ ______________________________________________________ |
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