经过好几天的努力终于写出来了，上次写的太垃圾了。写完才知道原来FFT的程序这么简单，都不如驱动数码管的程序复杂。
Radix-2的算法，输入32位数，从0到31。
程序所有文件
fft11.zip
(9.58 KB)
所有小数的旋转因子先乘32768,计算完后右移15位，目的是绕开小数计算
计算旋转因子的程序，比如FFT的第三步需要4个旋转因子，N就填8
#include <stdio.h>
#include <math.h>
#include <stdlib.h>
void main() {
float pi,sr,si;
int rr,ii, n,i;
n=8;
pi=3.1415927;
for(i=0;i<n/2;i++){
sr=cos(2*pi*i/n);
si=-sin(2*pi*i/n);
rr=sr*32768;
ii=si*32768;
printf("0x%04X,0x%04X,",rr,ii);
}
printf("\n");
}
计算器计算的
单片机计算的
从0x20000000开始到0X20000080是实部
从0X20000080开始到0X20000100是虚部
全部顺序排列
和计算器计算的大体对照下感觉差不多，单片机的输出的是十六进制，负数都是0XFFFFXXXX这样的。
FFT在STM32F030F4P6单片机上的程序
[url=home.php?mod=space&uid=72445]@[/url] stm32f030f4p6 asm
[url=home.php?mod=space&uid=31174]@fft[/url] 32点
.thumb
.syntax unified
.section .data
.equ STACKINIT, 0x20001000
.equ xuanzhuanyinzi, 0x20000120
xinxi: .ascii "fft-32dian-2018-01-04"
.align 4
shuru: .int 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
.int 16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31
hudie: .int 0,64,32,96,16,80,48,112,8,72,40,104,24,88,56,120
.int 4,68,36,100,20,84,52,116,12,76,44,108,28,92,60,124
fft3xuanzhuanyinzi:
.int 0x8000,0x0000,0x5A82,0xFFFFA57E,0x0000,0xFFFF8000,0xFFFFA57E,0xFFFFA57E
fft4xuanzhuanyinzi:
.int 0x8000,0x0000,0x7641,0xFFFFCF05,0x5A82,0xFFFFA57E,0x30FB,0xFFFF89BF,0x0000,0xFFFF8000,0xFFFFCF05,0xFFFF89BF,0xFFFFA57E,0xFFFFA57E,0xFFFF89BF,0xFFFFCF05
fft5xuanzhuanyinzi:
.int 0x8000,0x0000,0x7D8A,0xFFFFE708,0x7641,0xFFFFCF05,0x6A6D,0xFFFFB8E4,0x5A82,0xFFFFA57E,0x471C,0xFFFF9593,0x30FB,0xFFFF89BF,0x18F8,0xFFFF8276,0x0000,0xFFFF8000,0xFFFFE708,0xFFFF8276,0xFFFFCF05,0xFFFF89BF,0xFFFFB8E4,0xFFFF9593,0xFFFFA57E,0xFFFFA57E,0xFFFF9593,0xFFFFB8E4,0xFFFF89BF,0xFFFFCF05,0xFFFF8276,0xFFFFE708
.section .text
vectors:
.word STACKINIT
.word _start + 1
.word _nmi_handler + 1
.word _hard_fault + 1
.word 0
.word 0
.word 0
.word 0
.word 0
.word 0
.word 0
.word _svc_handler +1
.word 0
.word 0
.word _pendsv_handler +1
.align 2
_start:
_shizhong: @时钟设置
ldr r2, = 0x40022000 @FLASH访问控制
movs r1, # 0x32
str r1, [r2]
ldr r0, = 0x40021000 @ rcc
@0x34时钟控制寄存器 2 (RCC_CR2)
movs r1, # 0x01
str r1, [r0, # 0x34] @ HSI开14M时钟
_dengdai14mshizhongwending: @等14M时钟稳定
ldr r1, [r0, # 0x34]
lsls r1, r1, # 30 @ 左移30位
bpl _dengdai14mshizhongwending @ 等待14M时钟稳定
_neicunqingling: @ 0x1000的内存清零
@ 1K=1024BIT=0X400
ldr r0, = 0x20000000
movs r1, # 0
ldr r3, = 0x1000
_neicunqinglingxunhuan: @ 内存清零循环
subs r3, # 4
str r1, [r0, r3]
bne _neicunqinglingxunhuan @
_fftjisuan:
_fft1:
ldr r0, = shuru
ldr r1, = 0x20000000
movs r2, # 16
ldr r3, = hudie
_fft1xunhuan:
ldr r6, [r3]
ldr r7, [r3, # 0x04]
ldr r6, [r0, r6]
ldr r7, [r0, r7]
adds r4, r6, r7
subs r5, r6, r7
str r4, [r1]
str r5, [r1, # 0x04]
adds r1, r1, # 0x08
adds r3, r3, # 0x08
subs r2, r2, # 1
bne _fft1xunhuan
_fft2:
ldr r0, = 0x20000000
mov r4, r0
adds r4, r4, # 0x80
mov r8, r4
_fft2xunhuan:
ldr r4, [r0]
ldr r5, [r0, # 0x08]
ldr r6, [r0, # 0x04]
ldr r7, [r0, # 0x0c]
adds r1, r4, r5
subs r2, r4, r5
mov r3, r6 @0r
movs r4, # 0
subs r4, r4, r7 @0i
mov r5, r6 @3r
mov r6, r7 @3i
mov r7, r0
adds r7, r7, # 0x80
str r1, [r0]
str r2, [r0, # 0x08]
str r3, [r0, # 0x04]
str r4, [r7, # 0x04]
str r5, [r0, # 0x0c]
str r6, [r7, # 0x0c]
adds r0, r0, # 0x10
cmp r0, r8
bne _fft2xunhuan
_fft3:
ldr r6, = xuanzhuanyinzi
ldr r2, = fft3xuanzhuanyinzi
ldr r0, = 0x20000000
str r2, [r6]
movs r1, r0
adds r1, r1, # 0x80
mov r8, r1
mov r9, r0
mov r10, r2
movs r5, # 0x10
mov r11, r5
movs r5, # 4
mov r12, r5
bl _fftg
_fft4:
ldr r6, = xuanzhuanyinzi
ldr r2, = fft4xuanzhuanyinzi
ldr r0, = 0x20000000
str r2, [r6]
movs r1, r0
adds r1, r1, # 0x80
mov r8, r1
mov r9, r0
mov r10, r2
movs r5, # 0x20
mov r11, r5
movs r5, # 8
mov r12, r5
bl _fftg
_fft5:
ldr r6, = xuanzhuanyinzi
ldr r2, = fft5xuanzhuanyinzi
ldr r0, = 0x20000000
str r2, [r6]
movs r1, r0
adds r1, r1, # 0x80
mov r8, r1
mov r9, r0
mov r10, r2
movs r5, # 0x40
mov r11, r5
movs r5, # 16
mov r12, r5
bl _fftg
tingting:
b tingting
_fftg:
push {lr}
movs r4, # 0
mov lr, r4
_fftxunhuan:
mov r0, r9
mov r1, r8
mov r2, r10
mov r3, r11
ldr r4, [r0]
ldr r5, [r1]
ldr r6, [r0, r3]
ldr r7, [r1, r3]
ldr r3, [r2] @sr
ldr r2, [r2, # 0x04] @si
push {r4,r5}
mov r4, r6
muls r4, r4, r3
mov r5, r7
muls r5, r5, r2
subs r4, r4, r5 @r
asrs r4, r4, # 15
mov r5, r6
muls r5, r5, r2
muls r7, r7, r3
adds r7, r7, r5 @i
asrs r7, r7, # 15
pop {r2,r5}
adds r3, r2, r4 @0r
subs r2, r2, r4 @1r
adds r4, r5, r7
subs r5, r5, r7
mov r6, r11
str r3, [r0]
str r4, [r1]
str r2, [r0, r6]
str r5, [r1, r6]
adds r0, r0, # 0x04
adds r1, r1, # 0x04
mov r9, r0
mov r8, r1
mov r2, r10
adds r2, r2, # 0x08
mov r10, r2
mov r4, lr
adds r4, r4, # 1
mov lr, r4
mov r7, r12
cmp r4, r7
bne _fftxunhuan
movs r4, # 0
ldr r6, = xuanzhuanyinzi
ldr r5, = 0x20000080
ldr r6, [r6]
mov r10, r6
mov lr, r4
mov r7, r11
adds r0, r0, r7
adds r1, r1, r7
mov r9, r0
mov r8, r1
cmp r0, r5
bne _fftxunhuan
pop {pc}
_nmi_handler:
bx lr
_hard_fault:
bx lr
_svc_handler:
bx lr
_pendsv_handler:
bx lr
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