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_Slight_ optimization of peak calculation

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git-svn-id: svn://svn.rockbox.org/rockbox/trunk@8949 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Brandon Low 2006-03-07 23:10:24 +00:00
parent 838a7020c7
commit 06d085a952
1 changed files with 25 additions and 15 deletions
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40
firmware/pcm_playback.c
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@ -333,7 +333,7 @@ static int pcm_freq = 0x6; /* 44.1 is default */
/* NOTE: The order of these two variables is important if you use the iPod /* NOTE: The order of these two variables is important if you use the iPod
assembler optimised fiq handler, so don't change it. */ assembler optimised fiq handler, so don't change it. */
unsigned short* p IBSS_ATTR; unsigned short* p IBSS_ATTR;
long p_size IBSS_ATTR; size_t p_size IBSS_ATTR;
static void dma_start(const void *addr, size_t size) static void dma_start(const void *addr, size_t size)
{ {
@ -751,31 +751,41 @@ size_t pcm_get_bytes_waiting(void)
* every tenth sample would still be pretty accurate). * every tenth sample would still be pretty accurate).
*/ */
#define PEAK_SAMPLES (44100*2/HZ) /* 44100 samples * 2 / 100 Hz tick */ /* Check for a peak every PEAK_STRIDE samples */
#define PEAK_STRIDE 3 /* every 3rd sample is plenty... */ #define PEAK_STRIDE 3
/* Up to 1/50th of a second of audio for peak calculation */
/* This should use NATIVE_FREQUENCY, or eventually an adjustable freq. value */
#define PEAK_SAMPLES (44100/50)
void pcm_calculate_peaks(int *left, int *right) void pcm_calculate_peaks(int *left, int *right)
{ {
short *addr;
short *end;
{
#ifdef HAVE_UDA1380 #ifdef HAVE_UDA1380
long samples = (BCR0 & 0xffffff) / 4; size_t samples = (BCR0 & 0xffffff) / 4;
short *addr = (short *) (SAR0 & ~3); addr = (short *) (SAR0 & ~3);
#elif defined(HAVE_WM8975) || defined(HAVE_WM8758) || defined(HAVE_WM8731) #elif defined(HAVE_WM8975) || defined(HAVE_WM8758) || defined(HAVE_WM8731)
long samples = p_size / 4; size_t samples = p_size / 4;
short *addr = p; addr = p;
#elif defined(HAVE_TLV320) #elif defined(HAVE_TLV320)
long samples = 4; /* TODO X5 */ size_t samples = 4; /* TODO X5 */
short *addr = NULL; addr = NULL;
#endif #endif
if (samples > PEAK_SAMPLES) if (samples > PEAK_SAMPLES)
samples = PEAK_SAMPLES; samples = PEAK_SAMPLES - (PEAK_STRIDE - 1);
else
samples -= MIN((PEAK_STRIDE - 1), samples);
samples /= PEAK_STRIDE; end = addr + samples * 4;
}
if (left && right) { if (left && right) {
int left_peak = 0, right_peak = 0, value; int left_peak = 0, right_peak = 0;
while (samples--) { while (addr < end) {
int value;
if ((value = addr [0]) > left_peak) if ((value = addr [0]) > left_peak)
left_peak = value; left_peak = value;
else if (-value > left_peak) else if (-value > left_peak)
@ -798,7 +808,7 @@ void pcm_calculate_peaks(int *left, int *right)
if (right) if (right)
addr += (PEAK_STRIDE | 1); addr += (PEAK_STRIDE | 1);
while (samples--) { while (addr < end) {
if ((value = addr [0]) > peak_value) if ((value = addr [0]) > peak_value)
peak_value = value; peak_value = value;
else if (-value > peak_value) else if (-value > peak_value)