png: move DSP functions to their own DSP context.

1 files changed, 48 insertions, 0 deletions

diff --git a/libavcodec/pngdsp.c b/libavcodec/pngdsp.c
new file mode 100644
index 0000000..d40bf9c
--- /dev/null
+++ b/libavcodec/pngdsp.c
@@ -0,0 +1,48 @@
+/*
+ * PNG image format
+ * Copyright (c) 2008 Loren Merrit <lorenm@u.washington.edu>
+ *
+ * This file is part of Libav.
+ *
+ * Libav is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * Libav is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with Libav; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "libavutil/common.h"
+#include "png.h"
+#include "pngdsp.h"
+
+// 0x7f7f7f7f or 0x7f7f7f7f7f7f7f7f or whatever, depending on the cpu's native arithmetic size
+#define pb_7f (~0UL/255 * 0x7f)
+#define pb_80 (~0UL/255 * 0x80)
+
+static void add_bytes_l2_c(uint8_t *dst, uint8_t *src1, uint8_t *src2, int w)
+{
+    long i;
+    for (i = 0; i <= w - sizeof(long); i += sizeof(long)) {
+        long a = *(long *)(src1 + i);
+        long b = *(long *)(src2 + i);
+        *(long *)(dst + i) = ((a & pb_7f) + (b & pb_7f)) ^ ((a ^ b) & pb_80);
+    }
+    for (; i < w; i++)
+        dst[i] = src1[i] + src2[i];
+}
+
+void ff_pngdsp_init(PNGDSPContext *dsp)
+{
+    dsp->add_bytes_l2         = add_bytes_l2_c;
+    dsp->add_paeth_prediction = ff_add_png_paeth_prediction;
+
+    if (HAVE_MMX) ff_pngdsp_init_x86(dsp);
+}