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More FFT fun: No point in computing and combining the 2nd FFT if it's just being made null. Use the regular complex FFT (called by fftr anyway) and save ram and computation for a given number of bins.

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git-svn-id: svn://svn.rockbox.org/rockbox/trunk@26507 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Michael Sevakis 2010-06-03 08:55:36 +00:00
parent 6feac4a315
commit e0af34cb5f
1 changed files with 28 additions and 38 deletions
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66
apps/plugins/fft/fft.c
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@ -247,18 +247,14 @@ GREY_INFO_STRUCT
#include "_kiss_fft_guts.h" /* sizeof(struct kiss_fft_state) */
#include "const.h"
#if (LCD_WIDTH < LCD_HEIGHT)
#define LCD_SIZE LCD_HEIGHT
#else
#define LCD_SIZE LCD_WIDTH
#endif
#define LCD_SIZE MAX(LCD_WIDTH, LCD_HEIGHT)
#if (LCD_SIZE < 512)
#define FFT_SIZE 2048 /* 512*4 */
#elif (LCD_SIZE < 1024)
#define FFT_SIZE 4096 /* 1024*4 */
#if (LCD_SIZE <= 511)
#define FFT_SIZE 1024 /* 512*2 */
#elif (LCD_SIZE <= 1023)
#define FFT_SIZE 2048 /* 1024*2 */
#else
#define FFT_SIZE 8192 /* 2048*4 */
#define FFT_SIZE 4096 /* 2048*2 */
#endif
#ifdef HAVE_LCD_COLOR
@ -272,14 +268,9 @@ GREY_INFO_STRUCT
#endif
#define ARRAYLEN_IN (FFT_SIZE)
#define ARRAYLEN_OUT (FFT_SIZE/2)
#define ARRAYLEN_PLOT ((FFT_SIZE/4)-1) /* -1 to ignore DC bin */
#define ARRAYLEN_OUT (FFT_SIZE)
#define ARRAYLEN_PLOT (FFT_SIZE/2-1) /* FFT is symmetric, ignore DC */
#define BUFSIZE_FFT (sizeof(struct kiss_fft_state)+sizeof(kiss_fft_cpx)*(FFT_SIZE-1))
#define BUFSIZE_FFTR (BUFSIZE_FFT+sizeof(struct kiss_fftr_state)+sizeof(kiss_fft_cpx)*(FFT_SIZE*3/2))
#define BUFSIZE BUFSIZE_FFTR
#define FFT_ALLOC kiss_fftr_alloc
#define FFT_FFT kiss_fftr
#define FFT_CFG kiss_fftr_cfg
#define __COEFF(type,size) type##_##size
#define _COEFF(x, y) __COEFF(x,y) /* force the preprocessor to evaluate FFT_SIZE) */
@ -294,28 +285,28 @@ GREY_INFO_STRUCT
(CACHEALIGN_UP((len)*sizeof(type) + (sizeof(type)-1)) / sizeof(type))
/* Shared */
/* COP + CPU PCM */
static kiss_fft_scalar input[CACHEALIGN_UP_SIZE(kiss_fft_scalar, ARRAYLEN_IN)]
static kiss_fft_cpx input[CACHEALIGN_UP_SIZE(kiss_fft_scalar, ARRAYLEN_IN)]
CACHEALIGN_AT_LEAST_ATTR(4);
/* CPU+COP */
#if NUM_CORES > 1
/* Output queue indexes */
static volatile int output_head SHAREDBSS_ATTR = 0;
static volatile int output_tail SHAREDBSS_ATTR = 0;
/* The result is nfft/2+1 complex frequency bins from DC to Nyquist. */
static kiss_fft_cpx output[2][CACHEALIGN_UP_SIZE(kiss_fft_cpx, ARRAYLEN_OUT+1)]
/* The result is nfft/2 complex frequency bins from DC to Nyquist. */
static kiss_fft_cpx output[2][CACHEALIGN_UP_SIZE(kiss_fft_cpx, ARRAYLEN_OUT)]
SHAREDBSS_ATTR;
#else
/* Only one output buffer */
#define output_head 0
#define output_tail 0
/* The result is nfft/2+1 complex frequency bins from DC to Nyquist. */
static kiss_fft_cpx output[1][ARRAYLEN_OUT+1];
/* The result is nfft/2 complex frequency bins from DC to Nyquist. */
static kiss_fft_cpx output[1][ARRAYLEN_OUT];
#endif
/* Unshared */
/* COP */
static FFT_CFG fft_state SHAREDBSS_ATTR;
static char buffer[CACHEALIGN_UP_SIZE(char, BUFSIZE)]
static kiss_fft_cfg fft_state SHAREDBSS_ATTR;
static char fft_buffer[CACHEALIGN_UP_SIZE(char, BUFSIZE_FFT)]
CACHEALIGN_AT_LEAST_ATTR(4);
/* CPU */
static int32_t plot_history[ARRAYLEN_PLOT];
@ -399,10 +390,10 @@ static struct {
/************************* Math functions *************************/
/* Based on playing back a 0dB sweep tone */
#define QLOG_MAX 0x000865EF
/* Based on feeding-in a 0db sinewave at FS/4 */
#define QLOG_MAX 0x0009154B
/* fudge it a little or it's not very visbile */
#define QLIN_MAX (0x00001157 >> 1)
#define QLIN_MAX (0x00002266 >> 1)
/* Apply window function to input */
static void apply_window_func(enum fft_window_func mode)
@ -414,14 +405,14 @@ static void apply_window_func(enum fft_window_func mode)
case FFT_WF_HAMMING:
for(i = 0; i < ARRAYLEN_IN; ++i)
{
input[i] = (input[i] * HAMMING_COEFF[i] + 16384) >> 15;
input[i].r = (input[i].r * HAMMING_COEFF[i] + 16384) >> 15;
}
break;
case FFT_WF_HANN:
for(i = 0; i < ARRAYLEN_IN; ++i)
{
input[i] = (input[i] * HANN_COEFF[i] + 16384) >> 15;
input[i].r = (input[i].r * HANN_COEFF[i] + 16384) >> 15;
}
break;
}
@ -1135,8 +1126,8 @@ static void draw_spectrogram_horizontal(void)
/** functions use in single/multi configuration **/
static inline bool fft_init_fft_lib(void)
{
size_t size = sizeof(buffer);
fft_state = FFT_ALLOC(FFT_SIZE, 0, buffer, &size);
size_t size = sizeof(fft_buffer);
fft_state = kiss_fft_alloc(FFT_SIZE, 0, fft_buffer, &size);
if(fft_state == NULL)
{
@ -1159,12 +1150,12 @@ static inline bool fft_get_fft(void)
* do a proper spectrum analysis.*/
/* there are cases when we don't have enough data to fill the buffer */
if(count != ARRAYLEN_IN/2)
if(count != ARRAYLEN_IN)
{
if(count < ARRAYLEN_IN/2)
if(count < ARRAYLEN_IN)
return false;
count = ARRAYLEN_IN/2; /* too much - limit */
count = ARRAYLEN_IN; /* too much - limit */
}
int fft_idx = 0; /* offset in 'input' */
@ -1173,15 +1164,14 @@ static inline bool fft_get_fft(void)
{
kiss_fft_scalar left = *value++;
kiss_fft_scalar right = *value++;
input[fft_idx++] = (left + right) >> 1; /* to mono */
input[fft_idx++] = 0;
} while (--count > 0);
input[fft_idx].r = (left + right) >> 1; /* to mono */
} while (fft_idx++, --count > 0);
apply_window_func(graph_settings.window_func);
rb->yield();
FFT_FFT(fft_state, input, output[output_tail]);
kiss_fft(fft_state, input, output[output_tail]);
rb->yield();