> You cannot use unsigned values, because we need to sum samples (it means: > add positive and substract negative ones). If we are in positive range, we > can only add samples, so the final sum result is wrong.
Since the bug database at sourceforge seems to be completely forgotten I am reposting it here: http://sourceforge.net/tracker/?func=detail&aid=576153&group_id=27464&atid=390601 snd_pcm_mmap_*_avail may return negative value on some occasions. CONSIDER: buffer_size=80 (0x50), then boundary=0x50000000 let *appl.ptr= 0 and *hw.ptr=0x80000051 avail = *pcm->hw.ptr + pcm->buffer_size - *pcm->appl.ptr; // 0x80000001 == - 0x7FFFFFFF if (avail < 0) avail += pcm->boundary; else if ((snd_pcm_uframes_t) avail >= pcm->boundary) avail -= pcm->boundary; // here avail == 0xD0000001 == -0x2FFFFFFF This is not theoretical case. My application playing at 8 kHz crashes after 3 days (0x10000000/1000 seconds) Q: should the driver guarantee hw.ptr < boundary ??? I am keeping *appl.ptr at 0 and using snd_pcm_mmap_*_avail to give me the position to write into mmaped buffer. I am mixing streams directly in the buffer, and do not care if some streams do not come. These functions should simply return ((unsigned long)avail) % boundary instead of that funny += -= cases. And why there is no function which just simply returns the value of ((unsigned long)*pcm->hw.ptr)% boundary that is all what I need. I have to use at the moment: static inline int snd_pcm_gethwpos(snd_pcm_t *pcm) { snd_pcm_sframes_t ret = snd_pcm_avail_update(pcm); ret += snd_pcm_commited; if(ret<0) { ret = ((unsigned long) ret)%buffer_size; } return snd_pcm_avail_update(pcm)%buffer_size; } Best regards, -- Tomasz Motylewski ------------------------------------------------------- This sf.net email is sponsored by:ThinkGeek Two, two, TWO treats in one. http://thinkgeek.com/sf _______________________________________________ Alsa-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/alsa-devel
