[libpng17] Rearranged ARM-NEON optimizations to isolate the machine specific

code to the hardware subdirectory, and add comments to pngrutil.c so that
implementors of other optimizations will know what to do.

2 files changed, 76 insertions, 0 deletions

diff --git a/arm/arm_init.c b/arm/arm_init.c
new file mode 100644
index 000000000..6b0a925f2
--- /dev/null
+++ b/arm/arm_init.c
@@ -0,0 +1,74 @@
+
+/* filter_neon.S - NEON optimised filter functions
+ *
+ * Copyright (c) 2011 Glenn Randers-Pehrson
+ * Written by Mans Rullgard, 2011.
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ */
+#include "../pngpriv.h"
+
+/* __arm__ is defined by GCC, MSVC defines _M_ARM to the ARM version number */
+#if defined __linux__ && defined __arm__
+#include <stdio.h>
+#include <elf.h>
+#include <asm/hwcap.h>
+
+static int png_have_hwcap(unsigned cap)
+{
+   FILE *f = fopen("/proc/self/auxv", "r");
+   Elf32_auxv_t aux;
+   int have_cap = 0;
+
+   if (!f)
+      return 0;
+
+   while (fread(&aux, sizeof(aux), 1, f) > 0)
+   {
+      if (aux.a_type == AT_HWCAP &&
+          aux.a_un.a_val & cap)
+      {
+         have_cap = 1;
+         break;
+      }
+   }
+
+   fclose(f);
+
+   return have_cap;
+}
+#endif /* __linux__ && __arm__ */
+
+void
+png_init_filter_functions_neon(png_structp pp, unsigned int bpp)
+{
+#ifdef __arm__
+#ifdef __linux__
+   if (!png_have_hwcap(HWCAP_NEON))
+      return;
+#endif
+
+   pp->read_filter[PNG_FILTER_VALUE_UP-1] = png_read_filter_row_up_neon;
+
+   if (bpp == 3)
+   {
+      pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub3_neon;
+      pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg3_neon;
+      pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
+         png_read_filter_row_paeth3_neon;
+   }
+
+   else if (bpp == 4)
+   {
+      pp->read_filter[PNG_FILTER_VALUE_SUB-1] = png_read_filter_row_sub4_neon;
+      pp->read_filter[PNG_FILTER_VALUE_AVG-1] = png_read_filter_row_avg4_neon;
+      pp->read_filter[PNG_FILTER_VALUE_PAETH-1] =
+          png_read_filter_row_paeth4_neon;
+   }
+#else
+   PNG_UNUSED(pp)
+   PNG_UNUSED(bpp)
+#endif
+}
diff --git a/arm/filter_neon.S b/arm/filter_neon.S
index 63a5d8c17..9ce04d3be 100644
--- a/arm/filter_neon.S
+++ b/arm/filter_neon.S
@@ -9,6 +9,7 @@
  * and license in png.h
  */
 
+#ifdef __arm__
 #if defined(__linux__) && defined(__ELF__)
 .section .note.GNU-stack,"",%progbits /* mark stack as non-executable */
 #endif
@@ -223,3 +224,4 @@ func    png_read_filter_row_paeth3_neon, export=1
 
         pop             {r4,pc}
 endfunc
+#endif