diff options
| author | Brandon Low <lostlogic@rockbox.org> | 2006-03-07 23:10:24 +0000 |
|---|---|---|
| committer | Brandon Low <lostlogic@rockbox.org> | 2006-03-07 23:10:24 +0000 |
| commit | 06d085a952f35b58a0660696be39335a3f8a19e1 (patch) | |
| tree | a511cf65dcb55878019a375bc0067e447907deaf /firmware/pcm_playback.c | |
| parent | 838a7020c7a4b623ac11e8aa4588c815d3641b43 (diff) | |
| download | rockbox-06d085a952f35b58a0660696be39335a3f8a19e1.tar.gz rockbox-06d085a952f35b58a0660696be39335a3f8a19e1.zip | |
_Slight_ optimization of peak calculation
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@8949 a1c6a512-1295-4272-9138-f99709370657
Diffstat (limited to 'firmware/pcm_playback.c')
| -rw-r--r-- | firmware/pcm_playback.c | 40 |
1 files changed, 25 insertions, 15 deletions
diff --git a/firmware/pcm_playback.c b/firmware/pcm_playback.c index 75b3de4f90..0ae87f4310 100644 --- a/firmware/pcm_playback.c +++ b/firmware/pcm_playback.c @@ -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 assembler optimised fiq handler, so don't change it. */ 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) { @@ -751,31 +751,41 @@ size_t pcm_get_bytes_waiting(void) * every tenth sample would still be pretty accurate). */ -#define PEAK_SAMPLES (44100*2/HZ) /* 44100 samples * 2 / 100 Hz tick */ -#define PEAK_STRIDE 3 /* every 3rd sample is plenty... */ +/* Check for a peak every PEAK_STRIDE samples */ +#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) { + short *addr; + short *end; + { #ifdef HAVE_UDA1380 - long samples = (BCR0 & 0xffffff) / 4; - short *addr = (short *) (SAR0 & ~3); + size_t samples = (BCR0 & 0xffffff) / 4; + addr = (short *) (SAR0 & ~3); #elif defined(HAVE_WM8975) || defined(HAVE_WM8758) || defined(HAVE_WM8731) - long samples = p_size / 4; - short *addr = p; + size_t samples = p_size / 4; + addr = p; #elif defined(HAVE_TLV320) - long samples = 4; /* TODO X5 */ - short *addr = NULL; + size_t samples = 4; /* TODO X5 */ + addr = NULL; #endif - if (samples > PEAK_SAMPLES) - samples = PEAK_SAMPLES; + if (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) { - 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) left_peak = value; else if (-value > left_peak) @@ -798,7 +808,7 @@ void pcm_calculate_peaks(int *left, int *right) if (right) addr += (PEAK_STRIDE | 1); - while (samples--) { + while (addr < end) { if ((value = addr [0]) > peak_value) peak_value = value; else if (-value > peak_value) |