Index: third_party/libpng/contrib/arm-neon/README |
diff --git a/third_party/libpng/contrib/arm-neon/README b/third_party/libpng/contrib/arm-neon/README |
new file mode 100644 |
index 0000000000000000000000000000000000000000..b4248cf289792b259e86377e1d4630e213f4ccc2 |
--- /dev/null |
+++ b/third_party/libpng/contrib/arm-neon/README |
@@ -0,0 +1,83 @@ |
+OPERATING SYSTEM SPECIFIC ARM NEON DETECTION |
+-------------------------------------------- |
+ |
+Detection of the ability to execute ARM NEON on an ARM 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 arm/arm_init.c |
+by setting the macro PNG_ARM_NEON_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 arm/arm_init.o with the required macro definition. |
+ |
+For any of this code to be used the ARM NEON code must be enabled and run time |
+checks must be supported. I.e.: |
+ |
+#if PNG_ARM_NEON_OPT > 0 |
+#ifdef PNG_ARM_NEON_CHECK_SUPPORTED |
+ |
+This is done in a 'configure' build by passing configure the argument: |
+ |
+ --enable-arm-neon=check |
+ |
+Apart from the basic Linux implementation in contrib/arm-neon/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_neon(png_structp png_ptr); |
+ |
+That function must return 1 if ARM NEON 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. |