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      1 
      2 /* powerpc_init.c - POWERPC optimised filter functions
      3  *
      4  * Copyright (c) 2017 Glenn Randers-Pehrson
      5  * Written by Vadim Barkov, 2017.
      6  * Last changed in libpng 1.6.29 [March 16, 2017]
      7  *
      8  * This code is released under the libpng license.
      9  * For conditions of distribution and use, see the disclaimer
     10  * and license in png.h
     11  */
     12 /* Below, after checking __linux__, various non-C90 POSIX 1003.1 functions are
     13  * called.
     14  */
     15 #define _POSIX_SOURCE 1
     16 
     17 #include <stdio.h>
     18 #include "../pngpriv.h"
     19 
     20 #ifdef PNG_READ_SUPPORTED
     21 
     22 #if PNG_POWERPC_VSX_OPT > 0
     23 #ifdef PNG_POWERPC_VSX_CHECK_SUPPORTED /* Do run-time checks */
     24 /* WARNING: it is strongly recommended that you do not build libpng with
     25  * run-time checks for CPU features if at all possible.  In the case of the PowerPC
     26  * VSX instructions there is no processor-specific way of detecting the
     27  * presence of the required support, therefore run-time detection is extremely
     28  * OS specific.
     29  *
     30  * You may set the macro PNG_POWERPC_VSX_FILE to the file name of file containing
     31  * a fragment of C source code which defines the png_have_vsx function.  There
     32  * are a number of implementations in contrib/powerpc-vsx, but the only one that
     33  * has partial support is contrib/powerpc-vsx/linux.c - a generic Linux
     34  * implementation which reads /proc/cpufino.
     35  */
     36 #ifndef PNG_POWERPC_VSX_FILE
     37 #  ifdef __linux__
     38 #     define  PNG_POWERPC_VSX_FILE "contrib/powerpc-vsx/linux_aux.c"
     39 #  endif
     40 #endif
     41 
     42 #ifdef PNG_POWERPC_VSX_FILE
     43 
     44 #include <signal.h> /* for sig_atomic_t */
     45 static int png_have_vsx(png_structp png_ptr);
     46 #include PNG_POWERPC_VSX_FILE
     47 
     48 #else  /* PNG_POWERPC_VSX_FILE */
     49 #  error "PNG_POWERPC_VSX_FILE undefined: no support for run-time POWERPC VSX checks"
     50 #endif /* PNG_POWERPC_VSX_FILE */
     51 #endif /* PNG_POWERPC_VSX_CHECK_SUPPORTED */
     52 
     53 void
     54 png_init_filter_functions_vsx(png_structp pp, unsigned int bpp)
     55 {
     56    /* The switch statement is compiled in for POWERPC_VSX_API, the call to
     57     * png_have_vsx is compiled in for POWERPC_VSX_CHECK. If both are defined
     58     * the check is only performed if the API has not set the PowerPC option on
     59     * or off explicitly. In this case the check controls what happens.
     60     */
     61 
     62 #ifdef PNG_POWERPC_VSX_API_SUPPORTED
     63    switch ((pp->options >> PNG_POWERPC_VSX) & 3)
     64    {
     65       case PNG_OPTION_UNSET:
     66          /* Allow the run-time check to execute if it has been enabled -
     67           * thus both API and CHECK can be turned on.  If it isn't supported
     68           * this case will fall through to the 'default' below, which just
     69           * returns.
     70           */
     71 #endif /* PNG_POWERPC_VSX_API_SUPPORTED */
     72 #ifdef PNG_POWERPC_VSX_CHECK_SUPPORTED
     73          {
     74             static volatile sig_atomic_t no_vsx = -1; /* not checked */
     75 
     76             if (no_vsx < 0)
     77                no_vsx = !png_have_vsx(pp);
     78 
     79             if (no_vsx)
     80                return;
     81          }
     82 #ifdef PNG_POWERPC_VSX_API_SUPPORTED
     83          break;
     84 #endif
     85 #endif /* PNG_POWERPC_VSX_CHECK_SUPPORTED */
     86 
     87 #ifdef PNG_POWERPC_VSX_API_SUPPORTED
     88       default: /* OFF or INVALID */
     89          return;
     90 
     91       case PNG_OPTION_ON:
     92          /* Option turned on */
     93          break;
     94    }
     95 #endif
     96 
     97    /* IMPORTANT: any new internal functions used here must be declared using
     98     * PNG_INTERNAL_FUNCTION in ../pngpriv.h.  This is required so that the
     99     * 'prefix' option to configure works:
    100     *
    101     *    ./configure --with-libpng-prefix=foobar_
    102     *
    103     * Verify you have got this right by running the above command, doing a build
    104     * and examining pngprefix.h; it must contain a #define for every external
    105     * function you add.  (Notice that this happens automatically for the
    106     * initialization function.)
    107     */
    108    pp->read_filter[PNG_FILTER_VALUE_UP-1] = png_read_filter_row_up_vsx;
    109 
    110    if (bpp == 3)
    111    {
    112       pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub3_vsx;
    113       pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg3_vsx;
    114       pp->read_filter[PNG_FILTER_VALUE_PAETH-1] = png_read_filter_row_paeth3_vsx;
    115    }
    116 
    117    else if (bpp == 4)
    118    {
    119       pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub4_vsx;
    120       pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg4_vsx;
    121       pp->read_filter[PNG_FILTER_VALUE_PAETH-1] = png_read_filter_row_paeth4_vsx;
    122    }
    123 }
    124 #endif /* PNG_POWERPC_VSX_OPT > 0 */
    125 #endif /* READ */
    126