Alsa library has different version of read and driver interaction functions why?











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I was going through alsa library code, I wanted to know read function that is being used. However I see there are more than one version of read functions.
i.e 



.readi = snd_pcm_hw_readi

.readi = snd_pcm_ioplug_readi

.readi = snd_pcm_mmap_readi

.readi = snd_pcm_dshare_readi

.readi = snd_pcm_plugin_readi


I am not sure how does alsa library choose which function to use ?



what params make it choose different API's (like swparams ,hwparams)






linux-kernel alsa libalsa







share|improve this question






















  • Those are from different plugins.
    – CL.
    Nov 11 at 14:46










  • alsa.conf is the only file decides what plugins we use ?
    – vishwanath patil
    Nov 12 at 6:20










  • You give a device name to snd_pcm_open(), and that name is looked up in the configuration files.
    – CL.
    Nov 12 at 7:23












  • one varitation that I saw was "snd_pcm_plugin_fast_ops" that was decided based on hw_params and requested params. in "snd_pcm_plug_insert_plugins" function
    – vishwanath patil
    Nov 13 at 3:56

















up vote
0
down vote

favorite












I was going through alsa library code, I wanted to know read function that is being used. However I see there are more than one version of read functions.
i.e 



.readi = snd_pcm_hw_readi

.readi = snd_pcm_ioplug_readi

.readi = snd_pcm_mmap_readi

.readi = snd_pcm_dshare_readi

.readi = snd_pcm_plugin_readi


I am not sure how does alsa library choose which function to use ?



what params make it choose different API's (like swparams ,hwparams)






linux-kernel alsa libalsa







share|improve this question






















  • Those are from different plugins.
    – CL.
    Nov 11 at 14:46










  • alsa.conf is the only file decides what plugins we use ?
    – vishwanath patil
    Nov 12 at 6:20










  • You give a device name to snd_pcm_open(), and that name is looked up in the configuration files.
    – CL.
    Nov 12 at 7:23












  • one varitation that I saw was "snd_pcm_plugin_fast_ops" that was decided based on hw_params and requested params. in "snd_pcm_plug_insert_plugins" function
    – vishwanath patil
    Nov 13 at 3:56















up vote
0
down vote

favorite









up vote
0
down vote

favorite











I was going through alsa library code, I wanted to know read function that is being used. However I see there are more than one version of read functions.
i.e 



.readi = snd_pcm_hw_readi

.readi = snd_pcm_ioplug_readi

.readi = snd_pcm_mmap_readi

.readi = snd_pcm_dshare_readi

.readi = snd_pcm_plugin_readi


I am not sure how does alsa library choose which function to use ?



what params make it choose different API's (like swparams ,hwparams)






linux-kernel alsa libalsa







share|improve this question













I was going through alsa library code, I wanted to know read function that is being used. However I see there are more than one version of read functions.
i.e 



.readi = snd_pcm_hw_readi

.readi = snd_pcm_ioplug_readi

.readi = snd_pcm_mmap_readi

.readi = snd_pcm_dshare_readi

.readi = snd_pcm_plugin_readi


I am not sure how does alsa library choose which function to use ?



what params make it choose different API's (like swparams ,hwparams)






linux-kernel alsa libalsa




linux-kernel alsa libalsa






share|improve this question













share|improve this question











share|improve this question




share|improve this question










asked Nov 11 at 13:20









vishwanath patil

116




116












  • Those are from different plugins.
    – CL.
    Nov 11 at 14:46










  • alsa.conf is the only file decides what plugins we use ?
    – vishwanath patil
    Nov 12 at 6:20










  • You give a device name to snd_pcm_open(), and that name is looked up in the configuration files.
    – CL.
    Nov 12 at 7:23












  • one varitation that I saw was "snd_pcm_plugin_fast_ops" that was decided based on hw_params and requested params. in "snd_pcm_plug_insert_plugins" function
    – vishwanath patil
    Nov 13 at 3:56




















  • Those are from different plugins.
    – CL.
    Nov 11 at 14:46










  • alsa.conf is the only file decides what plugins we use ?
    – vishwanath patil
    Nov 12 at 6:20










  • You give a device name to snd_pcm_open(), and that name is looked up in the configuration files.
    – CL.
    Nov 12 at 7:23












  • one varitation that I saw was "snd_pcm_plugin_fast_ops" that was decided based on hw_params and requested params. in "snd_pcm_plug_insert_plugins" function
    – vishwanath patil
    Nov 13 at 3:56


















Those are from different plugins.
– CL.
Nov 11 at 14:46




Those are from different plugins.
– CL.
Nov 11 at 14:46












alsa.conf is the only file decides what plugins we use ?
– vishwanath patil
Nov 12 at 6:20




alsa.conf is the only file decides what plugins we use ?
– vishwanath patil
Nov 12 at 6:20












You give a device name to snd_pcm_open(), and that name is looked up in the configuration files.
– CL.
Nov 12 at 7:23






You give a device name to snd_pcm_open(), and that name is looked up in the configuration files.
– CL.
Nov 12 at 7:23














one varitation that I saw was "snd_pcm_plugin_fast_ops" that was decided based on hw_params and requested params. in "snd_pcm_plug_insert_plugins" function
– vishwanath patil
Nov 13 at 3:56






one varitation that I saw was "snd_pcm_plugin_fast_ops" that was decided based on hw_params and requested params. in "snd_pcm_plug_insert_plugins" function
– vishwanath patil
Nov 13 at 3:56



















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