michael@0: 
michael@0: /* arm_init.c - NEON optimised filter functions
michael@0:  *
michael@0:  * Copyright (c) 2014 Glenn Randers-Pehrson
michael@0:  * Written by Mans Rullgard, 2011.
michael@0:  * Last changed in libpng 1.6.10 [March 6, 2014]
michael@0:  *
michael@0:  * This code is released under the libpng license.
michael@0:  * For conditions of distribution and use, see the disclaimer
michael@0:  * and license in png.h
michael@0:  */
michael@0: /* Below, after checking __linux__, various non-C90 POSIX 1003.1 functions are
michael@0:  * called.
michael@0:  */
michael@0: #define _POSIX_SOURCE 1
michael@0: 
michael@0: #include "../pngpriv.h"
michael@0: 
michael@0: #ifdef PNG_READ_SUPPORTED
michael@0: #if PNG_ARM_NEON_OPT > 0
michael@0: #ifdef PNG_ARM_NEON_CHECK_SUPPORTED /* Do run-time checks */
michael@0: /* WARNING: it is strongly recommended that you do not build libpng with
michael@0:  * run-time checks for CPU features if at all possible.  In the case of the ARM
michael@0:  * NEON instructions there is no processor-specific way of detecting the
michael@0:  * presense of the required support, therefore run-time detectioon is extremely
michael@0:  * OS specific.
michael@0:  *
michael@0:  * You may set the macro PNG_ARM_NEON_FILE to the file name of file containing
michael@0:  * a fragment of C source code which defines the png_have_neon function.  There
michael@0:  * are a number of implementations in contrib/arm-neon, but the only one that
michael@0:  * has partial support is contrib/arm-neon/linux.c - a generic Linux
michael@0:  * implementation which reads /proc/cpufino.
michael@0:  */
michael@0: #ifndef PNG_ARM_NEON_FILE
michael@0: #  ifdef __linux__
michael@0: #     define PNG_ARM_NEON_FILE "linux.c"
michael@0: #  endif
michael@0: #endif
michael@0: 
michael@0: #ifdef PNG_ARM_NEON_FILE
michael@0: 
michael@0: #include <signal.h> /* for sig_atomic_t */
michael@0: static int png_have_neon(png_structp png_ptr);
michael@0: #include PNG_ARM_NEON_FILE
michael@0: 
michael@0: #else  /* PNG_ARM_NEON_FILE */
michael@0: #  error "PNG_ARM_NEON_FILE undefined: no support for run-time ARM NEON checks"
michael@0: #endif /* PNG_ARM_NEON_FILE */
michael@0: #endif /* PNG_ARM_NEON_CHECK_SUPPORTED */
michael@0: 
michael@0: #ifndef PNG_ALIGNED_MEMORY_SUPPORTED
michael@0: #  error "ALIGNED_MEMORY is required; set: -DPNG_ALIGNED_MEMORY_SUPPORTED"
michael@0: #endif
michael@0: 
michael@0: void
michael@0: png_init_filter_functions_neon(png_structp pp, unsigned int bpp)
michael@0: {
michael@0:    /* The switch statement is compiled in for ARM_NEON_API, the call to
michael@0:     * png_have_neon is compiled in for ARM_NEON_CHECK.  If both are defined
michael@0:     * the check is only performed if the API has not set the NEON option on
michael@0:     * or off explicitly.  In this case the check controls what happens.
michael@0:     *
michael@0:     * If the CHECK is not compiled in and the option is UNSET the behavior prior
michael@0:     * to 1.6.7 was to use the NEON code - this was a bug caused by having the
michael@0:     * wrong order of the 'ON' and 'default' cases.  UNSET now defaults to OFF,
michael@0:     * as documented in png.h
michael@0:     */
michael@0: #ifdef PNG_ARM_NEON_API_SUPPORTED
michael@0:    switch ((pp->options >> PNG_ARM_NEON) & 3)
michael@0:    {
michael@0:       case PNG_OPTION_UNSET:
michael@0:          /* Allow the run-time check to execute if it has been enabled -
michael@0:           * thus both API and CHECK can be turned on.  If it isn't supported
michael@0:           * this case will fall through to the 'default' below, which just
michael@0:           * returns.
michael@0:           */
michael@0: #endif /* PNG_ARM_NEON_API_SUPPORTED */
michael@0: #ifdef PNG_ARM_NEON_CHECK_SUPPORTED
michael@0:          {
michael@0:             static volatile sig_atomic_t no_neon = -1; /* not checked */
michael@0: 
michael@0:             if (no_neon < 0)
michael@0:                no_neon = !png_have_neon(pp);
michael@0: 
michael@0:             if (no_neon)
michael@0:                return;
michael@0:          }
michael@0: #ifdef PNG_ARM_NEON_API_SUPPORTED
michael@0:          break;
michael@0: #endif
michael@0: #endif /* PNG_ARM_NEON_CHECK_SUPPORTED */
michael@0: 
michael@0: #ifdef PNG_ARM_NEON_API_SUPPORTED
michael@0:       default: /* OFF or INVALID */
michael@0:          return;
michael@0: 
michael@0:       case PNG_OPTION_ON:
michael@0:          /* Option turned on */
michael@0:          break;
michael@0:    }
michael@0: #endif
michael@0: 
michael@0:    /* IMPORTANT: any new external functions used here must be declared using
michael@0:     * PNG_INTERNAL_FUNCTION in ../pngpriv.h.  This is required so that the
michael@0:     * 'prefix' option to configure works:
michael@0:     *
michael@0:     *    ./configure --with-libpng-prefix=foobar_
michael@0:     *
michael@0:     * Verify you have got this right by running the above command, doing a build
michael@0:     * and examining pngprefix.h; it must contain a #define for every external
michael@0:     * function you add.  (Notice that this happens automatically for the
michael@0:     * initialization function.)
michael@0:     */
michael@0:    pp->read_filter[PNG_FILTER_VALUE_UP-1] = png_read_filter_row_up_neon;
michael@0: 
michael@0:    if (bpp == 3)
michael@0:    {
michael@0:       pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub3_neon;
michael@0:       pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg3_neon;
michael@0:       pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
michael@0:          png_read_filter_row_paeth3_neon;
michael@0:    }
michael@0: 
michael@0:    else if (bpp == 4)
michael@0:    {
michael@0:       pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub4_neon;
michael@0:       pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg4_neon;
michael@0:       pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
michael@0:           png_read_filter_row_paeth4_neon;
michael@0:    }
michael@0: }
michael@0: #endif /* PNG_ARM_NEON_OPT > 0 */
michael@0: #endif /* PNG_READ_SUPPORTED */