1 files changed, 73 insertions, 0 deletions

diff --git a/apps/codecs/libtremor/ffmpeg_render_line.h b/apps/codecs/libtremor/ffmpeg_render_line.h
new file mode 100644
index 0000000000..c429c274e6
--- /dev/null
+++ b/apps/codecs/libtremor/ffmpeg_render_line.h
@@ -0,0 +1,73 @@
+/**
+ * @file
+ * Common code for Vorbis I encoder and decoder
+ * @author Denes Balatoni  ( dbalatoni programozo hu )
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg 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.
+ *
+ * FFmpeg 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 FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/* render_line and friend taken from ffmpeg (libavcodec/vorbis.c) */
+static inline void render_line_unrolled(int x, int y, int x1,
+                                        int sy, int ady, int adx,
+                                        ogg_int32_t *buf)
+{
+    int err = -adx;
+    x -= x1 - 1;
+    buf += x1 - 1;
+    while (++x < 0) {
+        err += ady;
+        if (err >= 0) {
+            err += ady - adx;
+            y   += sy;
+            buf[x] = MULT31_SHIFT15(buf[x],FLOOR_fromdB_LOOKUP[y]);
+            x++;
+        }
+        buf[x] = MULT31_SHIFT15(buf[x],FLOOR_fromdB_LOOKUP[y]);
+    }
+    if (x <= 0) {
+        if (err + ady >= 0)
+            y += sy;
+        buf[x] = MULT31_SHIFT15(buf[x],FLOOR_fromdB_LOOKUP[y]);
+    }
+}
+
+static void render_line(int x0, int y0, int x1, int y1, ogg_int32_t *buf)
+{
+    int dy  = y1 - y0;
+    int adx = x1 - x0;
+    int ady = abs(dy);
+    int sy  = dy < 0 ? -1 : 1;
+    buf[x0] = MULT31_SHIFT15(buf[x0],FLOOR_fromdB_LOOKUP[y0]);
+    if (ady*2 <= adx) { // optimized common case
+        render_line_unrolled(x0, y0, x1, sy, ady, adx, buf);
+    } else {
+        int base = dy / adx;
+        int x    = x0;
+        int y    = y0;
+        int err  = -adx;
+        ady -= abs(base) * adx;
+        while (++x < x1) {
+            y += base;
+            err += ady;
+            if (err >= 0) {
+                err -= adx;
+                y   += sy;
+            }
+            buf[x] = MULT31_SHIFT15(buf[x],FLOOR_fromdB_LOOKUP[y]);
+        }
+    }
+}