decus
NO. 8-292    Fast Fourier Transform and Fast
             Welch-Fourier Transform
             FWFT - #2 Symbolic 200-311

	6424 / INITIALIZE CLOCK
	CLA CLL
	ADCC	/	CLEAR A/D CHANNEL
	DCA INDX / INITIALIZE INDEX
	TAD NUM
	CIA
	DCA PNTR / SET POINTS COUNTER
SAMWT,	ION / INTERRUPT WAIT ROUTINE
HERE,	JMP HERE
SER0,	6424 / RESET CLOCK
	CLA CLL
	ADCV / SAMPLE SIGNAL
	TAD INDX
	6777 / BIT INVERT INDEX
	TAD RSA / SET DATA ARRAY ADDRESSES
	DCA RA
ORDF,	ADSF
	JMP .-1
	ADRB	/ READ A/D
	TAD HALF
	CLL RAL
	DCA I RA / EVEN POINTS TO REAL ARRAY
	ISZ INDX / INCREMENT INDEX
	ISZ PNTR
	JMP SAMWT
	JMP FWFT	/ SAMPLING COMPLETE
OUTPT,	6077 / SET CRT INTENSITY
	DCA ARG1
	TAD NUM
	CIA
	DCA CNTR
	TAD RSA
	DCA RA
DISPL,	TAD ARG1 / DISPLAY RESULTS
	DXL
	IAC
	DCA ARG1
	TAD I RA
	CLL RAR / SHIFT FOR DISPLAY
	CLL RAR
	DYS
	CLA
	ISZ RA
	ISZ CNTR
	JMP DISPL
	JMP OUTPT / DISPLAY SWEEP FINI
HALF,1000 / OVER-RANGE PREVENTIVE
INV,	TAD RSA / REORDER SPECTRUM AND
	DCA RA / INVERSE TRANSFORM
	TAD NUM
	CLL RAR
	CIA
	DCA CNTR
	DCA INDX
RED,	TAD INDX
	6777 / BIT INVERT NODAL INDEX
	TAD RSA
	DCA RA2
	TAD I RA
	CLL RAR
	TAD M2 / SCALE TO PREVENT OVERFLOW
	MQL
	TAD I RA2
	CLL RAR
	TAD M2
	DCA I RA
	CLA MQA
	DCA I RA2
	ISZ RA
	ISZ INDX
	ISZ CNTR
	JMP RED
	JMP FWFT / START TRANSFORM
M2,2000 / 1-1/2
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