Home | History | Annotate | only in /external/libpng/contrib/mips-msa
Up to higher level directory
NameDateSize
linux.c21-Aug-20181.4K
README21-Aug-20183.4K

README

      1 OPERATING SYSTEM SPECIFIC MIPS MSA DETECTION
      2 --------------------------------------------
      3 
      4 Detection of the ability to execute MIPS MSA on an MIPS processor requires
      5 operating system support.  (The information is not available in user mode.)
      6 
      7 HOW TO USE THIS
      8 ---------------
      9 
     10 This directory contains C code fragments that can be included in mips/mips_init.c
     11 by setting the macro PNG_MIPS_MSA_FILE to the file name in "" or <> at build
     12 time.  This setting is not recorded in pnglibconf.h and can be changed simply by
     13 rebuilding mips/msa_init.o with the required macro definition.
     14 
     15 For any of this code to be used the MIPS MSA code must be enabled and run time
     16 checks must be supported.  I.e.:
     17 
     18 #if PNG_MIPS_MSA_OPT > 0
     19 #ifdef PNG_MIPS_MSA_CHECK_SUPPORTED
     20 
     21 This is done in a 'configure' build by passing configure the argument:
     22 
     23    --enable-mips-msa=check
     24 
     25 Apart from the basic Linux implementation in contrib/mips-msa/linux.c this code
     26 is unsupported.  That means that it is not even compiled on a regular basis and
     27 may be broken in any given minor release.
     28 
     29 FILE FORMAT
     30 -----------
     31 
     32 Each file documents its testing status as of the last time it was tested (which
     33 may have been a long time ago):
     34 
     35 STATUS: one of:
     36    SUPPORTED: This indicates that the file is included in the regularly
     37          performed test builds and bugs are fixed when discovered.
     38    COMPILED: This indicates that the code did compile at least once.  See the
     39          more detailed description for the extent to which the result was
     40          successful.
     41    TESTED: This means the code was fully compiled into the libpng test programs
     42          and these were run at least once.
     43 
     44 BUG REPORTS: an email address to which to send reports of problems
     45 
     46 The file is a fragment of C code. It should not define any 'extern' symbols;
     47 everything should be static.  It must define the function:
     48 
     49 static int png_have_msa(png_structp png_ptr);
     50 
     51 That function must return 1 if MIPS MSA instructions are supported, 0 if not.
     52 It must not execute png_error unless it detects a bug.  A png_error will prevent
     53 the reading of the PNG and in the future, writing too.
     54 
     55 BUG REPORTS
     56 -----------
     57 
     58 If you mail a bug report for any file that is not SUPPORTED there may only be
     59 limited response.  Consider fixing it and sending a patch to fix the problem -
     60 this is more likely to result in action.
     61 
     62 CONTRIBUTIONS
     63 -------------
     64 
     65 You may send contributions of new implementations to
     66 png-mng-implement (a] sourceforge.net.  Please write code in strict C90 C where
     67 possible.  Obviously OS dependencies are to be expected.  If you submit code you
     68 must have the authors permission and it must have a license that is acceptable
     69 to the current maintainer; in particular that license must permit modification
     70 and redistribution.
     71 
     72 Please try to make the contribution a single file and give the file a clear and
     73 unambiguous name that identifies the target OS.  If multiple files really are
     74 required put them all in a sub-directory.
     75 
     76 You must also be prepared to handle bug reports from users of the code, either
     77 by joining the png-mng-implement mailing list or by providing an email for the
     78 "BUG REPORTS" entry or both.  Please make sure that the header of the file
     79 contains the STATUS and BUG REPORTS fields as above.
     80 
     81 Please list the OS requirements as precisely as possible.  Ideally you should
     82 also list the environment in which the code has been tested and certainly list
     83 any environments where you suspect it might not work.
     84