[libpng15] Imported from libpng-1.5.16beta06.tar

scripts/pnglibconf.dfa

@@ -27,7 +27,7 @@ file pnglibconf.h scripts/pnglibconf.dfa PNGLCONF_H
 # The syntax is detailed in scripts/options.awk, this is a summary
 # only:
 #
-# setting <name> [default]
+# setting <name> [requires ...] [default]
 #    #define PNG_<name> <value>  /* value comes from current setting */
 # option <name> [requires ...] [if ...] [enables ...] [disabled]
 #    #define PNG_<name>_SUPPORTED if the requirements are met and
@@ -191,12 +191,23 @@ option WRITE enables WRITE_INT_FUNCTIONS
 
 setting FILTER_OPTIMIZATIONS
 
-# This option turns on runtime checks for ARM NEON support, it is irrelevant
-# on other platforms and it is irrelevant unless NEON code is turned on.  Checks
-# are on by default
-
-option ARM_NEON_CHECK
-
+# Implementation specific control of the optimizations, enabled by those
+# hardware or software options that need it (typically when run-time choices
+# must be made by the user)
+option SET_OPTION disabled
+ 
+# These options are specific to the ARM NEON hardware optimizations:
+#
+# ARM_NEON: the optimization itself
+# ARM_NEON_API: allow the optimization to be switched on with png_set_hardware
+# ARM_NEON_CHECK: compile a run-time check to see if Neon extensions are
+#                 supported, this is poorly supported and deprectated - use the
+#                 png_set_hardware API.
+option ARM_NEON disabled,
+   sets FILTER_OPTIMIZATIONS png_init_filter_functions_neon
+option ARM_NEON_API disabled enables SET_OPTION ARM_NEON
+option ARM_NEON_CHECK disabled enables ARM_NEON
+ 
 # Generic options - affect both read and write.
 
 option WARNINGS
@@ -369,6 +380,12 @@ option INCH_CONVERSIONS
 
 option BUILD_GRAYSCALE_PALETTE
 
+# This changes the default for the ARM NEON optimizations according to
+# __ARM_NEON__
+@#ifdef __ARM_NEON__
+@#  define PNG_ARM_NEON_SUPPORTED
+@#endif
+
 # IN DEVELOPMENT
 # These are currently experimental features; define them if you want