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Assembly Source File | 1986-07-25 | 13.6 KB | 428 lines

TITL 'TMS32011 BASED 212A MODEM ' IDT 'MAIN' OPTION XREF,TUNLST ********************************************************** *** - DSP MODEM PROGRAM - *** ********************************************************** *** TASKMASA.ASM --- This source contains the rewrite *** *** of the modem code to time slice *** *** the tasks and to operate with *** *** a CODEC device for operation on *** *** the demo board. *** *** This interum update executes the 9.6KHz sample *** *** rate. It includes the updates to operate with a *** *** CODEC device and a TMS32011. It interfaces to a *** *** TMS7041 device for the DTE interface. *** *** This version include experimental code to skip *** *** the FIR bandpass filter. It also will try some *** *** experimental code to fine tune carrier tracking. *** *** *** *** WRITTEN BY: PETER EHLIG *** *** *** *** COPYRIGHT TEXAS INSTRUMENTS, 07/25/86 *** *** *** ********************************************************** DEF MASTER DEF BAUDST,BDCLK1,BDCLK2,DECODE DEF DEMOD,DEMODB,DUMMY,DUMXMT DEF GETDBT,OUT,TRENDS REF TSKSEQ,TSKXMT REF PLLC,BPLLC,WAIT,COMD,COEF,WAIT1 PAGE COPY TASKMAS.EQU *************************************************************** * The following code is the time sliced code task master. * * The routine monitors the status of the modem operations * * and sequences the code appropriately. * *************************************************************** MASTER EQU $ LAC ONE,4 CHECK OPERATING STATUS FOR AND RECST FOR CARRIER DETECT BNZ CARLCK IF CDT THEN RUN MODEM B NORMAL IF DETECTED EXECUTE NORMAL SEQUENCE DBUG1 NOP * STORE IN XMTOUT TO SEE ON SCOPE OUT ERRSIG,3 * FOR DEBUG PURPOSES OUT BEROUT,3 * FOR DEBUG PURPOSES OUT RECI,3 * FOR DEBUG PURPOSES OUT RECQ,3 * FOR DEBUG PURPOSES OUT DPOINT,3 * FOR DEBUG PURPOSES OUT CTRND,3 * FOR DEBUG PURPOSES * * UPDATE CARRIER ANGLE AT SAMPLE RATE * LAC RALPHA * COMPUTE ADDRESS OF NEXT ADD RDELTA * POINT FOR TABLE. AND MASK1 * KEEP MOD128, MASK=>7FFF. SACL RALPHA * SAVE NEXT ADDRESS LAC ONE,2 * SEE IF XMIT SQLCH BIT SET AND RECST * IN THE STATUS REGISTER BGZ WAIT1 * B MASXMT GO ON TO XMT TASK MASTER * CARLCK LACK PLLC TBLR PLL1 LACK BPLLC TBLR BPLL1 NORMAL EQU $ LAC SAMPLE DECREMENT THE SAMPLE COUNT SUB ONE TO CHECK FOR END OF BAUD BGEZ OVRSAM IF NOT THEN SKIP COUNT RESET LACK 15 RESTART THE SAMPLE COUNTER AT 15 OVRSAM SACL SAMPLE SAVE NEW COUNT VALUE LACK TSKSEQ GET ADDRESS OF TOP OF TABLE ADD SAMPLE ADD IN OFFSET TBLR TEMP GET THE PROGRAM ADDRESS LAC TEMP FOR THE TASK CALL CALA EXECUTE THE APPROPRIATE TASK B DBUG1 RETURN TO THE WAIT LOOP * MASXMT EQU $ LAC SAMXMT DECREMENT THE SAMPLE COUNT SUB ONE TO CHECK FOR END OF BAUD BGEZ OVRSM1 IF NOT THEN SKIP COUNT RESET LACK 15 RESTART THE SAMPLE COUNTER AT 15 OVRSM1 SACL SAMXMT SAVE NEW COUNT VALUE LACK TSKXMT GET ADDRESS OF TOP OF TABLE ADD SAMXMT ADD IN OFFSET TBLR TEMP GET THE PROGRAM ADDRESS LAC TEMP FOR THE TASK CALL CALA EXECUTE THE APPROPRIATE TASK B WAIT1 WAIT FOR NEXT SAMPLE TIMEOUT PAGE DUMXMT EQU $ RET * ******************************************************** * GETDBT EQU $ IN XMTD,PA7 * GET NEW DIBIT LACK >30 AND XMTD * CHECK COMMAND BITS BZ COMD * IF ZERO SQT MODEM, IDLE * LACK COEF * RECYCLE IF FINISHED SACL XPTR DMOV XIBUF1 * SHIFT UP THE FILTER DMOV XIBUF0 * TO MAKE ROOM FOR DMOV XQBUF1 * FOR THE NEW DATA VALUE DMOV XQBUF0 * JUST INPUT * LACK 3 AND XMTD * NEW DIBIT FROM 7000 ADD OFSET1 * LOOKUP NEWPHASE TBLR XNEWPH LAC XOLDPH * GET OLDPHASE. ADD XNEWPH * ADD NEW PHASE. AND MASK3 * MASK WITH >0006. SACL XOLDPH * STORE BACK 'NEW' OLDPHASE. ADD INDXPH * LOOKUP I & Q INPUTS. TBLR XIBUF0 ADD ONE TBLR XQBUF0 RET * DUMMY CALL DEMOD ATTEMPT DEMODULATION RET RETURN TO TASK MASTER * BAUDST EQU $ SHOW START OF BAUD LAC MASK1 SACL DPOINT CALL DEMOD RET * PAGE * DEMODB EQU $ ZAC SUB MASK1 SACL DPOINT LACK >BF RESET THE CURRENT ZERO CROSSING AND RECST FLAG IN THE STATUS REGISTER AND SACL RECST SAVE IT (BIT6=0 FOR MIDDLE OF BAUD) ********************************************************** ***** DEMODUATE THE PASSBAND SIGNAL. ***** ********------------------------------------------******** ***** RCVR. CARRIER SINE(COSINE) WAVE GENERATOR ***** ********************************************************** DEMOD EQU $ LAC RALPHA,8 * DELTA IS THE INCREMENT. ADD ONE,15 * ROUND IT UP SACH TEMP * ISOLATE INTEGER PORTION. LAC TEMP * MASK TO WITH THE 128 WORD AND MASK2 * SINE TABLE ADD OFSET0 * ADD INDEX TO SINE TABLE. TBLR SINA * SINE VALUE, (Q15). LACK >20 * ADD 90 DEGREES TO ADD TEMP * THE ANGLE TO GET AND MASK2 * THE COSINE VALUE ADD OFSET0 * ADD INDEX TO COSINE TABLE. TBLR COSA * COSINE VALUE, (Q15). * ********************************************************* * CONT1 EQU $ LT ISUM MPY COSA * A=(Yi * cosA)/2 PAC LT QSUM MPY SINA APAC * A=(Yi * cosA)/2 + (Yq * sin A)/2 SACH RECI,1 * RECI= (Yi * cosA) + (Yq * sinA) * *---MUST DETERMINE SIGN OF I AND Q FOR ERROR CORRECTION---* * LAC RECI * DETERMINE SIGN OF I CHAN BGZ DM1 LAC MINUS1 B DM2 DM1 LAC PLUS1 DM2 SACL SIGNI * SAVE SIGN OF I LT ISUM MPY SINA PAC * A = (Yi * sinA)/2 LT QSUM MPY COSA SPAC * A =[(Yi * sinA)/2] - [(Yq * cosA)/2] SACH RECQ,1 * RECQ = (Yi * sinA) - (Yq * cosA) * LAC RECQ * DETERMINE SIGN OF Q CHAN BGZ DM3 LAC MINUS1 B DM4 DM3 LAC PLUS1 DM4 SACL SIGNQ * *---MUST DETERMINE ENERGY FOR BAUD CLOCK ALLIGNMENT---* * LT RECI MPY RECI * FIND I**2 PAC LT RECQ MPY RECQ * FIND Q**2 APAC SACH ENRGY * ENERGY = (I**2) + (Q**2) * RET RETURN TO CALLING SEQUENCE ********------------------------------------------******** ***** COMPUTE CARRIER ERROR SIGNAL. ***** ***** e(t) = RECI*SIGNQ - RECQ*SIGNI ***** ********------------------------------------------******** COMERR ZAC LT RECI MPY SIGNQ LTA RECQ MPY SIGNI SPAC SACH ERROR,1 * ERROR IS IN Q12 ********------------------------------------------******** ***** LOOP FILTER ****** ********------------------------------------------******** ZAC LT PLL2 MPY ERROR LTA PLL1 MPY ERRSIG APAC SACH ERRSIG,1 * ERRSIG IS IN Q12 ********************************************************* * CORRECT PHASE ERROR ONLY AT MIDDLE OF BAUD * ********************************************************* ************************************************************ * Adjust carrier phase +/- * * one table entry if - (2*trshld) > error > trshld * * two table entries if - (2*trshld) < error >> trshld * * RALPHA is current local carrier table index.(in MSB ) * ************************************************************ CKEROR LAC ERRSIG * BGZ ERR1 * If error is -ve add threshold ADD TRSHD1 * BGZ ERRETN * Still -ve?... add again ADD TRSHD1 * BGZ SUB1A * still -ve?... LAC CTRND * GET THE CARRIER UPDATE TREND SUB ONE,1 * ADD TWO SACL CTRND * AND SAVE IT LAC RALPHA * Error >> trshld; add 2 to index SUB ONE,9 * B DERR2 * DBUG CODE-TRAPS ON CDT LOSS SUB1A LAC CTRND * GET THE CARRIER UPDATE TREND SUB ONE * ADD ONE SACL CTRND * AND SAVE IT LAC RALPHA * Error > trshld; add 1 to index SUB ONE,8 * B ERR2 * ERR1 SUB TRSHD1 * Error ia +ve; subtract threshold BLZ ERRETN * Error > trshld SUB TRSHD1 * see if error >> trshld BLZ ADD1A * No...add one to index LAC CTRND * GET THE CARRIER UPDATE TREND ADD ONE,1 * SUBTRACT TWO SACL CTRND * AND SAVE IT LAC RALPHA * Yes...add 2 to index ADD ONE,9 * SUB 2 same as ADD >7E in modulo 128 DERR2 AND MASK1 SACL RALPHA LAC DBUGC COMPARE BAUD COUNT SUB ONE,11 TO 2048 BLZ DERR3 IF < THEN SYSTEM NOT STABLE NOP ELSE ENABLE TRAP CODE NOP BY STARTING DBUGC2 COUNT DERR3 RET ADD1A LAC CTRND * GET THE CARRIER UPDATE TREND ADD ONE * SUBTRACT ONE SACL CTRND * AND SAVE IT LAC RALPHA * ADD ONE,8 * ERR2 AND MASK1 * Keep RALPHA modulo 128 SACL RALPHA * save new index RET * Return with corrected RALPHA ERRETN LAC ONE,4 OR RECST TO ACTIVE IN THE STATUS REGISTER SACL RECST AND SAVE IT RETA RET ****************************************************** * OUT XMITS NEW DECODED DIBITS TO THE 7000 * OUT EQU $ LACK >3C * MASK IN CDT,EDT & SQLCH BITS AND RECST * FROM RECST REG. OR RDIBIT * TO THE DIBIT VALUE SACL BITOUT *AND SAVE THE SHIFTED VALUE OUT BITOUT,PA7 *XMIT TO 7000 CALL DEMOD * DEMODULATE TO CONTINUE PLOT RET * BACK TO CALLER * ********------------------------------------------******** ***** PHASE DECODING - BINARY TO GRAY CODE ***** * THIS ROUTINE CALCULATES PHASE SHIFT FROM OLDPH TO THE * * CURRENT ABSOLUTE PHASE, GREY CODE RESULT TO GET DIBIT * ********------------------------------------------******** DECODE EQU $ OUT RECI,PA4 OUT RECQ,PA4 LAC RECI * DETERMINE ABSOLUTE PHASE BGZ ABS1 LAC RECQ BGZ ABS2 LACK 2 * PHASE IS 2 (0 deg) B DIFFER * ABS2 LACK 3 * PHASE IS 3 (270 deg) B DIFFER * ABS1 LAC RECQ BGZ ABS3 LACK 1 * PHASE IS 1 (180 deg) B DIFFER * ABS3 LACK 0 * PHASE IS 0 (90 deg) * * DIFFER SACL TEMP SUB ROLDPH * SUBTRACT PREVIOUS ABSO- BGEZ DF1 * LUTE PHASE (BINARY CODED) ADD ONE,2 * ADD 4 DF1 ADD RPHSE * MAP PHASE CHANGE TO DIBIT TBLR RDIBIT NOP LAC TEMP SACL ROLDPH CALL COMERR * COMPUTE ERROR USING PRESENT PHASE * AND CORRECT PHASE OF LOCAL CARRIER CALL DEMOD * DEMODULATE TO CONTINUE PLOT RET *********************************************************** ***** BAUD CLOCK ALLIGNMENT **** *********************************************************** BDCLK1 CALL DEMOD LAC ENRGY SACL PENRGY RET BDCLK2 CALL DEMOD LAC ONE,6 AND RECST * TEST IF CORRECTION IS MADE BNZ RETB * IF SO RETURN LAC ENRGY SUB PENRGY * FORM ERROR SIGNAL SACL BERROR ********-------------------------------------------********** **** LOOP FILTER ******* ********-------------------------------------------********** ZAC LT BPLL2 MPY BERROR LTA BPLL1 MPY BEROUT APAC SACH BEROUT,1 * BEROUT IN Q14 * *---APPLY CORRECTION * LAC BEROUT BGEZ POS ADD TRSHD2 BGEZ RETB ADD TRSHD2 BGEZ SUB1B LAC SAMPLE SUB ONE,1 SACL SAMPLE B RETB SUB1B LAC SAMPLE SUB ONE SACL SAMPLE B RETB POS SUB TRSHD2 BLZ RETB SUB TRSHD2 BLZ ADD1B LAC SAMPLE ADD ONE,1 SACL SAMPLE B RETB ADD1B LAC SAMPLE ADD ONE SACL SAMPLE RETB LAC ONE,6 OR RECST SACL RECST RET ************************************************************************** PAGE *********************************************************** ***** CARRIER TREND UPDATE **** ***** **** ***** THIS ROUTINE CALCULATES THE CARRIER SHIFT **** ***** TRENDS OVER 16 BAUD INTERVALS (256 SAMPLES) **** ***** AND CALCULATES A FRACTIONAL VALUE TO INCREASE **** ***** (OR DECREASE) THE SINE TABLE STEP VALUE **** ***** **** *********************************************************** TRENDS EQU $ CALL DEMOD DEMODULATE TO CONTINUE PLOT LAC ONE,4 CHECK OPERATING STATUS FOR AND RECST CARRIER DETECT BZ NOTYET IF NO CDT THEN DON'T UPDATE LAC TRNDCT DECREMENT TREND BAUD COUNT SUB ONE BY ONE TO SEE IF IT IS READY FOR BZ TUPDT NEXT UPDATE SACL TRNDCT NO, SKIP UPDATE NOTYET RET AND RETURN TO CALLING SEQUENCE * TUPDT LACK 16 RESET THE TREND BAUD COUNTER SACL TRNDCT TO 16 FOR NEXT BLOCK LAC CTRND GET THE TREND VALUE BLZ OTRND1 IF NEGATIVE HANDLE APPROPRIATELY SUB ONE,2 COMPARE IT TO 4 BLEZ OTRND IF CTRND < 4 THEN LAC RDELTA GET THE SINE INCREMENT VALUE ADD ONE INCREMENT CARRIER DELTA SACL RDELTA AND SAVE IT OTRND ZAC CLEAR THE ACCUMULATOR SACL CTRND TO CLEAR OUT OLD TREND VALUE RET RETURN TO CALLING SEQUENCE OTRND1 ADD ONE,2 COMPARE TO -4 BGEZ OTRND IF CTRND > -4 THEN LAC RDELTA GET THE SINE INCREMENT VALUE SUB ONE DECREMENT THE CARRIER DELTA SACL RDELTA AND SAV IT B OTRND AND FINISH * END