contrib/neon/neon.ac

# LIBPNG EXTENSION: NEON
#
# ARM NEON (SIMD) support.
#
# This file contains configure.ac additions to libpng configure to enable
# building of the ARM NEON filter optimizations.
#
AC_ARG_ENABLE([arm-neon],
   AS_HELP_STRING([[[--enable-arm-neon]]],
      [Enable ARM NEON optimizations: =no/off, check, api, yes/on:]
      [no/off: disable the optimizations; check: use internal checking code]
      [(deprecated and poorly supported); api: disable by default, enable by]
      [a call to png_set_option; yes/on: turn on unconditionally.]
      [If not specified: determined by the compiler.]),
   [case "$enableval" in
      no|off)
         # disable the default enabling on __ARM_NEON__ systems:
         AC_DEFINE([PNG_ARM_NEON_OPT], [0],
                   [Disable ARM Neon optimizations])
         # Prevent inclusion of the assembler files below:
         enable_arm_neon=no;;
      check)
         AC_DEFINE([PNG_ARM_NEON_CHECK_SUPPORTED], [],
                   [Check for ARM Neon support at run-time]);;
      api)
         AC_DEFINE([PNG_ARM_NEON_API_SUPPORTED], [],
                   [Turn on ARM Neon optimizations at run-time]);;
      yes|on)
         AC_DEFINE([PNG_ARM_NEON_OPT], [2],
                   [Enable ARM Neon optimizations])
         AC_MSG_WARN([--enable-arm-neon: please specify 'check' or 'api', if]
            [you want the optimizations unconditionally pass -mfpu=neon]
            [to the compiler.]);;
      *)
         AC_MSG_ERROR([--enable-arm-neon=${enable_arm_neon}: invalid value])
   esac])

# Add ARM specific files to all builds where the host_cpu is arm ('arm*') or
# where ARM optimizations were explicitly requested (this allows a fallback if a
# future host CPU does not match 'arm*')

AM_CONDITIONAL([PNG_ARM_NEON],
   [test "$enable_arm_neon" != 'no' &&
    case "$host_cpu" in
      arm*|aarch64*) :;;
      *)    test "$enable_arm_neon" != '';;
    esac])