lavu: replace int/float punning functions

The existing functions defined in intfloat_readwrite.[ch] are
both slow and incorrect (infinities are not handled).

This introduces a new header with fast, inline conversion
functions using direct union punning assuming an IEEE-754
system, an assumption already made throughout the code.

The one use of Intel/Motorola extended 80-bit format is
replaced by simpler code sufficient under the present
constraints (positive normal values).

The old functions are marked deprecated and retained for
compatibility.

Signed-off-by: Mans Rullgard <mans@mansr.com>

1 files changed, 73 insertions, 0 deletions

diff --git a/libavutil/intfloat.h b/libavutil/intfloat.h
new file mode 100644
index 0000000000..9db624a6ce
--- /dev/null
+++ b/libavutil/intfloat.h
@@ -0,0 +1,73 @@
+/*
+ * Copyright (c) 2011 Mans Rullgard
+ *
+ * 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
+ */
+
+#ifndef AVUTIL_INTFLOAT_H
+#define AVUTIL_INTFLOAT_H
+
+#include <stdint.h>
+#include "attributes.h"
+
+union av_intfloat32 {
+    uint32_t i;
+    float    f;
+};
+
+union av_intfloat64 {
+    uint64_t i;
+    double   f;
+};
+
+/**
+ * Reinterpret a 32-bit integer as a float.
+ */
+static av_always_inline float av_int2float(uint32_t i)
+{
+    union av_intfloat32 v = { .i = i };
+    return v.f;
+}
+
+/**
+ * Reinterpret a float as a 32-bit integer.
+ */
+static av_always_inline uint32_t av_float2int(float f)
+{
+    union av_intfloat32 v = { .f = f };
+    return v.i;
+}
+
+/**
+ * Reinterpret a 64-bit integer as a double.
+ */
+static av_always_inline double av_int2double(uint64_t i)
+{
+    union av_intfloat64 v = { .i = i };
+    return v.f;
+}
+
+/**
+ * Reinterpret a double as a 64-bit integer.
+ */
+static av_always_inline uint64_t av_double2int(double f)
+{
+    union av_intfloat64 v = { .f = f };
+    return v.i;
+}
+
+#endif /* AVUTIL_INTFLOAT_H */