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Diffstat (limited to 'libpng/contrib/mips-msa/README')
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diff --git a/libpng/contrib/mips-msa/README b/libpng/contrib/mips-msa/README new file mode 100644 index 00000000..10acc936 --- /dev/null +++ b/libpng/contrib/mips-msa/README @@ -0,0 +1,83 @@ +OPERATING SYSTEM SPECIFIC MIPS MSA DETECTION +-------------------------------------------- + +Detection of the ability to execute MIPS MSA on an MIPS processor requires +operating system support. (The information is not available in user mode.) + +HOW TO USE THIS +--------------- + +This directory contains C code fragments that can be included in mips/mips_init.c +by setting the macro PNG_MIPS_MSA_FILE to the file name in "" or <> at build +time. This setting is not recorded in pnglibconf.h and can be changed simply by +rebuilding mips/msa_init.o with the required macro definition. + +For any of this code to be used the MIPS MSA code must be enabled and run time +checks must be supported. I.e.: + +#if PNG_MIPS_MSA_OPT > 0 +#ifdef PNG_MIPS_MSA_CHECK_SUPPORTED + +This is done in a 'configure' build by passing configure the argument: + + --enable-mips-msa=check + +Apart from the basic Linux implementation in contrib/mips-msa/linux.c this code +is unsupported. That means that it is not even compiled on a regular basis and +may be broken in any given minor release. + +FILE FORMAT +----------- + +Each file documents its testing status as of the last time it was tested (which +may have been a long time ago): + +STATUS: one of: + SUPPORTED: This indicates that the file is included in the regularly + performed test builds and bugs are fixed when discovered. + COMPILED: This indicates that the code did compile at least once. See the + more detailed description for the extent to which the result was + successful. + TESTED: This means the code was fully compiled into the libpng test programs + and these were run at least once. + +BUG REPORTS: an email address to which to send reports of problems + +The file is a fragment of C code. It should not define any 'extern' symbols; +everything should be static. It must define the function: + +static int png_have_msa(png_structp png_ptr); + +That function must return 1 if MIPS MSA instructions are supported, 0 if not. +It must not execute png_error unless it detects a bug. A png_error will prevent +the reading of the PNG and in the future, writing too. + +BUG REPORTS +----------- + +If you mail a bug report for any file that is not SUPPORTED there may only be +limited response. Consider fixing it and sending a patch to fix the problem - +this is more likely to result in action. + +CONTRIBUTIONS +------------- + +You may send contributions of new implementations to +png-mng-implement@sourceforge.net. Please write code in strict C90 C where +possible. Obviously OS dependencies are to be expected. If you submit code you +must have the authors permission and it must have a license that is acceptable +to the current maintainer; in particular that license must permit modification +and redistribution. + +Please try to make the contribution a single file and give the file a clear and +unambiguous name that identifies the target OS. If multiple files really are +required put them all in a sub-directory. + +You must also be prepared to handle bug reports from users of the code, either +by joining the png-mng-implement mailing list or by providing an email for the +"BUG REPORTS" entry or both. Please make sure that the header of the file +contains the STATUS and BUG REPORTS fields as above. + +Please list the OS requirements as precisely as possible. Ideally you should +also list the environment in which the code has been tested and certainly list +any environments where you suspect it might not work. |