1 files changed, 67 insertions, 0 deletions
diff --git a/libavutil/float2half.h b/libavutil/float2half.h
new file mode 100644
index 0000000000..d6aaab8278
--- /dev/null
+++ b/libavutil/float2half.h
@@ -0,0 +1,67 @@
+/*
+ * 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
+ */
+
+#ifndef AVUTIL_FLOAT2HALF_H
+#define AVUTIL_FLOAT2HALF_H
+
+#include <stdint.h>
+
+static void float2half_tables(uint16_t *basetable, uint8_t *shifttable)
+{
+    for (int i = 0; i < 256; i++) {
+        int e = i - 127;
+
+        if (e < -24) { // Very small numbers map to zero
+            basetable[i|0x000]  = 0x0000;
+            basetable[i|0x100]  = 0x8000;
+            shifttable[i|0x000] = 24;
+            shifttable[i|0x100] = 24;
+        } else if (e < -14) { // Small numbers map to denorms
+            basetable[i|0x000] = (0x0400>>(-e-14));
+            basetable[i|0x100] = (0x0400>>(-e-14)) | 0x8000;
+            shifttable[i|0x000] = -e-1;
+            shifttable[i|0x100] = -e-1;
+        } else if (e <= 15) { // Normal numbers just lose precision
+            basetable[i|0x000] = ((e + 15) << 10);
+            basetable[i|0x100] = ((e + 15) << 10) | 0x8000;
+            shifttable[i|0x000] = 13;
+            shifttable[i|0x100] = 13;
+        } else if (e < 128) { // Large numbers map to Infinity
+            basetable[i|0x000]  = 0x7C00;
+            basetable[i|0x100]  = 0xFC00;
+            shifttable[i|0x000] = 24;
+            shifttable[i|0x100] = 24;
+        } else { // Infinity and NaN's stay Infinity and NaN's
+            basetable[i|0x000]  = 0x7C00;
+            basetable[i|0x100]  = 0xFC00;
+            shifttable[i|0x000] = 13;
+            shifttable[i|0x100] = 13;
+        }
+    }
+}
+
+static uint16_t float2half(uint32_t f, uint16_t *basetable, uint8_t *shifttable)
+{
+    uint16_t h;
+
+    h = basetable[(f >> 23) & 0x1ff] + ((f & 0x007fffff) >> shifttable[(f >> 23) & 0x1ff]);
+
+    return h;
+}
+
+#endif /* AVUTIL_FLOAT2HALF_H */