Hi! In this moment i've been hacking on the cs46xx alsa driver and hopefully i've got something that can make any fustraded cs46xx user/developer a little bit happier. Public documentation about the cs4630 dont seems to exist and as we already know, and Cirrus have not been very helpful providing us such necesary technical information. Finally Tom. W at Cirrus have provided me some DSP assembler sources, and some other related C++ sources. With that references i've able to find out some internals of the cs4630 and get a little bit further.
The CS4630 runs a mini Real-Time OS inside, called SPOS (Stream Processing OS I guess ...), parts of the SPOS is located in ROM memory on the CS4630 and CS4612, on the CS4610 got no ROM, and the hole SPOS needs be loaded in RAM. Then it's up to user/driver to setup which tasks should be running inside the SPOS, basically here we one basic entry to care of, the SCB (stream controll block), then we have 4 task tree, Hyper Foreground, Foreground, and Background. A SCB entry got a few basic things to care of, a address pointer to the next SCB list, a sublist address pointer, a function entry pointer. Then it has a lot of other relevant variables which depends on which task uses the SCB, but no documentation about this, so it's only to test && guess. In the DSP image with the current ALSA driver all tasks are statically setup when load the image. When the drivers pokes and peeks on the BA1 address space what it actually does is to modify and read parameters from a SCB task running in the DSP. So I've been working on using the .osp files provided by the Windows driver. To .osp contains a EXPORT segment where from the driver obtain the task entry when setting up a SCB, (or a task tree). The .osp provided by Windows driver dont contain any parameter data, which means that all tasks and SCB needs to be setup by the driver. When a the CODE in a .osp file is loaded into the DSP on other addres then 0x0000 all "call()", and "goto xxxx" instructions needs to be fixed up. In this moment I've wroten a program named "ospparser" then generates .h from a .osp which contains a table with all exported symbol, code, sample and parameter segments. Indirectly i can successfully load cwc4630.osp, cwcasync.osp, cwcsnoop.osp code into DSP, do all necesary fixups, and have everything working just a before, (as with current ALSA driver) All SCB's and tasktrees are setup by the driver. Today i manage to get "signals" out from the SPDIFO interface, however the sound is very distorcionated, totally broken, and my minidisc dont wont record it, course some copyright bit in the stream that i've got no idea how i been able to configure it in such way. To make multiple PCM channel, secondary CODEC to work is just to setup the necesary SCB's entries, which is hard to know how to do without any documenation. Well, if you want take a look at my changes to the cs46xx driver, however the difference is not "hearable" yet, there a lot of work done, download my code at this locations: http://www.cucumelo.org/~gorm/alsa-driver-0.9.0rc2-bs20020721.tar.gz http://www.cucumelo.org/~gorm/ospparser.tar.gz /Benny ------------------------------------------------------- This sf.net email is sponsored by:ThinkGeek Welcome to geek heaven. http://thinkgeek.com/sf _______________________________________________ Alsa-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/alsa-devel
