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.ARMS_off ;enable assembler for ARMS=0
.CPL_on ;enable assembler for CPL=1
.mmregs ;enable mem mapped register names
.global _bit_rev_data
.global _fft_data
.global _window
.global _bit_rev
.copy "macro.asm"
.sect ".data"
N .set 1024
K_FFT_SIZE .set 1024
.align 4*N
_bit_rev_data .space 16*2*N ; Output of bit reversing function
.align 4*N
_fft_data .space 16*2*N ; FFT output buffer
.sect ".text"
_bit_rev
ENTER_ASM
MOV #_fft_data, AR3
MOV #_bit_rev_data, AR7
MOV AR7, AR2
MOV #K_FFT_SIZE-1, BRC0
MOV #K_FFT_SIZE, T0
RPTB bit_rev_end-1
MOV dbl(*AR3), AC0
MOV AC0, dbl(*AR2+)
AMAR *(AR3+T0B)
bit_rev_end:
LEAVE_ASM
RET
; If you need any more assembly subroutines, make sure you name them
; _name, and include a ".global _name" directive at the top. Also,
; don't forget to use ENTER_ASM at the beginning, and LEAVE_ASM
; and RET at the end!
/*****************************************************************/
/* lab4fft.c */
/* Douglas L. Jones */
/* University of Illinois at Urbana-Champaign */
/* January 19, 1992 */
/* Changed for use w/ short integers and lookup table for ECE420 */
/* Matt Kleffner */
/* February 10, 2004 */
/* */
/* fft: in-place radix-2 DIT DFT of a complex input */
/* */
/* Permission to copy and use this program is granted */
/* as long as this header is included. */
/* */
/* WARNING: */
/* This file is intended for educational use only, since most */
/* manufacturers provide hand-tuned libraries which typically */
/* include the fastest fft routine for their DSP/processor */
/* architectures. High-quality, open-source fft routines */
/* written in C (and included in MATLAB) can be found at */
/* http://www.fftw.org */
/* */
/* #defines expected in lab4.h */
/* N: length of FFT: must be a power of two */
/* logN: N = 2**logN */
/* */
/* 16-bit-limited input/output (must be defined elsewhere) */
/* real: integer array of length N with real part of data */
/* imag: integer array of length N with imag part of data */
/* */
/* sinetables.h must */
/* 1) #define Nt to an equal or greater power of two than N */
/* 2) contain the following integer arrays with */
/* element magnitudes bounded by M = 2**15-1: */
/* costable: M*cos(-2*pi*n/Nt), n=0,1,...,Nt/2-1 */
/* sintable: M*sin(-2*pi*n/Nt), n=0,1,...,Nt/2-1 */
/* */
/*****************************************************************/
#include "sinetables.h"
void fft(void)
{
int i,j,k,n1,n2,n3;
int c,s,a,t,Wr,Wi;
j = 0; /* bit-reverse */
n2 = N >> 1;
for (i=1; i < N - 1; i++)
{
n1 = n2;
while ( j >= n1 )
{
j = j - n1;
n1 = n1 >> 1;
}
j = j + n1;
if (i < j)
{
t = real[i];
real[i] = real[j];
real[j] = t;
t = imag[i];
imag[i] = imag[j];
imag[j] = t;
}
}
/* FFT */
n2 = 1; n3 = Nt;
for (i=0; i < logN; i++)
{
n1 = n2; /* n1 = 2**i */
n2 = n2 + n2; /* n2 = 2**(i+1) */
n3 = n3 >> 1; /* cos/sin arg of -6.283185307179586/n2 */
a = 0;
for (j=0; j < n1; j++)
{
c = costable[a];
s = sintable[a];
a = a + n3;
for (k=j; k < N; k=k+n2)
{
/* Code for standard 32-bit hardware, */
/* with real,imag limited to 16 bits */
/*
Wr = (c*real[k+n1] - s*imag[k+n1]) >> 15;
Wi = (s*real[k+n1] + c*imag[k+n1]) >> 15;
real[k+n1] = (real[k] - Wr) >> 1;
imag[k+n1] = (imag[k] - Wi) >> 1;
real[k] = (real[k] + Wr) >> 1;
imag[k] = (imag[k] + Wi) >> 1;
*/
/* End standard 32-bit code */
/* Code for TI TMS320C54X series */
/*
Wr = ((long int)(c*real[k+n1]) - (long int)(s*imag[k+n1])) >> 15;
Wi = ((long int)(s*real[k+n1]) + (long int)(c*imag[k+n1])) >> 15;
real[k+n1] = ((long int)real[k] - (long int)Wr) >> 1;
imag[k+n1] = ((long int)imag[k] - (long int)Wi) >> 1;
real[k] = ((long int)real[k] + (long int)Wr) >> 1;
imag[k] = ((long int)imag[k] + (long int)Wi) >> 1;
*/
/* End code for TMS320C54X series */
/* Intrinsic code for TMS320C55X series */
Wr = _ssub(_smpy(c, real[k+n1]), _smpy(s, imag[k+n1]));
Wi = _sadd(_smpy(s, real[k+n1]), _smpy(c, imag[k+n1]));
real[k+n1] = _sshl(_ssub(real[k], Wr),-1);
imag[k+n1] = _sshl(_ssub(imag[k], Wi),-1);
real[k] = _sshl(_sadd(real[k], Wr),-1);
imag[k] = _sshl(_sadd(imag[k], Wi),-1);
/* End intrinsic code for TMS320C55X series */
/* Intrinsic code for TMS320C54X series */
/*
Wr = _ssub(_smpy(c, real[k+n1]), _smpy(s, imag[k+n1]));
Wi = _sadd(_smpy(s, real[k+n1]), _smpy(c, imag[k+n1]));
real[k+n1] = _sshl(_ssub(real[k], Wr),-1);
imag[k+n1] = _sshl(_ssub(imag[k], Wi),-1);
real[k] = _sshl(_sadd(real[k], Wr),-1);
imag[k] = _sshl(_sadd(imag[k], Wi),-1);
*/
/* End intrinsic code for TMS320C54X series */
}
}
}
return;
}
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