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lavu: replace int/float punning functions

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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>
This commit is contained in:
Mans Rullgard
2011-11-27 14:04:16 +00:00
parent 5b3265a718
commit 3383a53e7d
23 changed files with 152 additions and 76 deletions
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73
libavutil/intfloat.h Normal file
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/*
* 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 */