rfft256.asm

seed傅立叶变换程序

;***********************************************************
; Version 2.20.01                                           
;***********************************************************
;*****************************************************************************
;  Function:	 rfft256
;  Description:  real FFT
;
;  Copyright Texas instruments Inc, 1998
;-----------------------------------------------------------------------------
; Revision History:
;
; 1.00Beta  R. Piedra, 8/31/98. Original real FFT code.
;	- C-callable
;	- Created unpack macro
;	- Uses cfft.asm code version 1.00Beta
;
; 1.00	 A. Aboagye 10/15/98
;	 - added scale option as a parameter
; 2.00   Li Yuan 05/07/01
;        - fixed stack pointer index
;
;*****************************************************************************
N        .set       128   ; NUMBER OF POINTS FOR FFT
NREAL	 .set	    256   ; NUMBER OF POINTS FOR FFT(real)

	.include "macros.asm"
	.include "unpack.asm"
	.include "sintabr.q15"

        .mmregs

; Far-mode adjustment
; -------------------

	.if __far_mode
offset	.set 1			; far mode uses one extra location for ret addr  ll
	.else
offset	.set 0
	.endif

	.asg	(0), DATA
	.asg	(1), SIN45
	.asg	(4), save_ar7		; stack description
	.asg	(5), save_ar6		; stack description
	.asg	(6), save_ar1
	.asg	(7), ret_addr
	.asg	(8+offset), scale
					; x in A

;*****************************************************************************
	 .def	_rfft256
	 .text
_rfft256

; Preserve registers
; ------------------
	pshm	ar1
	pshm	ar6
	pshm	ar7
        PSHM    ST0                                 ; 1 cycle
        PSHM    ST1                                 ; 1 cycle
        RSBX    OVA                                 ; 1 cycle
        RSBX    OVB                                 ; 1 cycle

; Preserve local variables
; ------------------------

	frame	-2
	nop

; Get Arguments
; -------------

	stl	a,*sp(DATA)

	.if   N>4		; ??? no need
	st    #5a82h,*sp(SIN45)
        .endif

; Set modes
; ---------
	orm   #0100010101011110b,*(ST1) ; ASM=-2 , FRACT=1, sbx=1;CPL=1(compiler)

; Execute
; -------

	combo5xx		     ; FFT CODE for STAGES 1 and 2
        stage3                       ; MACRO WITH CODE FOR STAGE 3
        stdmacro 4,8,8,16,sin4,cos4  ; stage,outloopcnter,loopcnter,index
        stdmacro 5,4,16,32,sin5,cos5 ; stage,outloopcnter,loopcnter,index
        stdmacro 6,2,32,64,sin6,cos6 ; stage,outloopcnter,loopcnter,index
        laststag 7,sin7,cos7         ; MACRO WITH CODE FOR STAGE 7
	unpack	sin8,cos8

; Return
;--------

	frame	+2
        POPM    ST1                                 ; 1 cycle
        POPM    ST0                                 ; 1 cycle
	popm	ar7
	popm	ar6
	popm	ar1

	.if	__far_mode
	fretd
	.else
	retd
	.endif
	nop
	nop

;end of file. please do not remove. it is left here to ensure that no lines of code are removed by any editor