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88d1e2b2b0
These additions might overflow the signed range for large input values. Converting to unsigned before the addition rather than after avoids such undefined behaviour. The result under normal two's complement wraparound remains unchanged. Signed-off-by: Mans Rullgard <mans@mansr.com>
99 lines
2.9 KiB
C
99 lines
2.9 KiB
C
/*
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* portable IEEE float/double read/write functions
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*
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* Copyright (c) 2005 Michael Niedermayer <michaelni@gmx.at>
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*
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* This file is part of Libav.
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*
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* Libav is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* Libav is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with Libav; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* portable IEEE float/double read/write functions
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*/
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#include <stdint.h>
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#include "mathematics.h"
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#include "intfloat_readwrite.h"
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double av_int2dbl(int64_t v){
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if((uint64_t)v+v > 0xFFEULL<<52)
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return NAN;
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return ldexp(((v&((1LL<<52)-1)) + (1LL<<52)) * (v>>63|1), (v>>52&0x7FF)-1075);
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}
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float av_int2flt(int32_t v){
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if((uint32_t)v+v > 0xFF000000U)
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return NAN;
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return ldexp(((v&0x7FFFFF) + (1<<23)) * (v>>31|1), (v>>23&0xFF)-150);
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}
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double av_ext2dbl(const AVExtFloat ext){
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uint64_t m = 0;
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int e, i;
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for (i = 0; i < 8; i++)
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m = (m<<8) + ext.mantissa[i];
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e = (((int)ext.exponent[0]&0x7f)<<8) | ext.exponent[1];
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if (e == 0x7fff && m)
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return NAN;
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e -= 16383 + 63; /* In IEEE 80 bits, the whole (i.e. 1.xxxx)
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* mantissa bit is written as opposed to the
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* single and double precision formats. */
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if (ext.exponent[0]&0x80)
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m= -m;
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return ldexp(m, e);
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}
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int64_t av_dbl2int(double d){
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int e;
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if ( !d) return 0;
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else if(d-d) return 0x7FF0000000000000LL + ((int64_t)(d<0)<<63) + (d!=d);
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d= frexp(d, &e);
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return (int64_t)(d<0)<<63 | (e+1022LL)<<52 | (int64_t)((fabs(d)-0.5)*(1LL<<53));
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}
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int32_t av_flt2int(float d){
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int e;
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if ( !d) return 0;
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else if(d-d) return 0x7F800000 + ((d<0)<<31) + (d!=d);
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d= frexp(d, &e);
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return (d<0)<<31 | (e+126)<<23 | (int64_t)((fabs(d)-0.5)*(1<<24));
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}
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AVExtFloat av_dbl2ext(double d){
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struct AVExtFloat ext= {{0}};
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int e, i; double f; uint64_t m;
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f = fabs(frexp(d, &e));
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if (f >= 0.5 && f < 1) {
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e += 16382;
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ext.exponent[0] = e>>8;
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ext.exponent[1] = e;
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m = (uint64_t)ldexp(f, 64);
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for (i=0; i < 8; i++)
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ext.mantissa[i] = m>>(56-(i<<3));
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} else if (f != 0.0) {
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ext.exponent[0] = 0x7f; ext.exponent[1] = 0xff;
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if (f != INFINITY)
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ext.mantissa[0] = ~0;
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}
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if (d < 0)
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ext.exponent[0] |= 0x80;
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return ext;
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}
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