www.pudn.com > x28x_FFT.rar > rfft32br.asm

;======================================================================== 
; 
; File Name     : rfft_brc.asm 
;  
; Originator    : Advanced Embeeded Control  
;                 Texas Instruments  
;  
; Description   : This file contains source code to suffle the 2N-point real sequence 
;                 as N-point complex sequence in bit reversed order 
; 
; Date          : 26/2/2002 
;====================================================================== 
;  
; Routine Type  : C Callable 
;  
; Usage : 
; void rfft_brc(int *src, int *dst, ushort n) 
; This function shuffles 2N-point in-order array and stores it as N-point complex 
; array in bit-reversed order. This is helpful for Real FFT computation on the 2N-point 
; real sequence using N-point complex FFT module 
;===================================================================== 
; SOURCE ARRAY 
;         |  X(0)   | 
;         |  X(1)   | 
;         |  X(2)   | 
;         |  X(3)   | 
;            : 
;            : 
;         | X(2N-1) | 
;===================================================================== 
 
 
               .def _RFFT32_brev 
  
_RFFT32_brev:   
                 
            MOVL    XAR0,XAR4       ; XAR0->src 
            NOP     *,ARP5 
             
            MOV     AH,AL           ; AH=size 
            LSR     AH,#1           ; AH=size/2 
            MOVZ    AR7,AH          ; ZAR7=size/2 
            SUBB    XAR7,#1         ; XAR7=(size/2)-1 
 
            CMPR    0               ; TC=1, if src==dst 
            BF      off_place,NTC   ; If not equal, jump to off place bit rev 
 
             
next_data1:     
            MOVL    XT,*XAR4        ; XT=*src 
            MOVL    P,*XAR5         ; P=*dst 
            MOVL    XAR0,XAR4       ; XAR0=src 
            CMPR    2               ; check src