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/*
* 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_HALF2FLOAT_H
#define AVUTIL_HALF2FLOAT_H
#include <stdint.h>
typedef struct Half2FloatTables {
uint32_t mantissatable[3072];
uint32_t exponenttable[64];
uint16_t offsettable[64];
} Half2FloatTables;
static uint32_t convertmantissa(uint32_t i)
{
int32_t m = i << 13; // Zero pad mantissa bits
int32_t e = 0; // Zero exponent
while (!(m & 0x00800000)) { // While not normalized
e -= 0x00800000; // Decrement exponent (1<<23)
m <<= 1; // Shift mantissa
}
m &= ~0x00800000; // Clear leading 1 bit
e += 0x38800000; // Adjust bias ((127-14)<<23)
return m | e; // Return combined number
}
static void init_half2float_tables(Half2FloatTables *t)
{
t->mantissatable[0] = 0;
for (int i = 1; i < 1024; i++)
t->mantissatable[i] = convertmantissa(i);
for (int i = 1024; i < 2048; i++)
t->mantissatable[i] = 0x38000000UL + ((i - 1024) << 13UL);
for (int i = 2048; i < 3072; i++)
t->mantissatable[i] = t->mantissatable[i - 1024] | 0x400000UL;
t->mantissatable[2048] = t->mantissatable[1024];
t->exponenttable[0] = 0;
for (int i = 1; i < 31; i++)
t->exponenttable[i] = i << 23;
for (int i = 33; i < 63; i++)
t->exponenttable[i] = 0x80000000UL + ((i - 32) << 23UL);
t->exponenttable[31]= 0x47800000UL;
t->exponenttable[32]= 0x80000000UL;
t->exponenttable[63]= 0xC7800000UL;
t->offsettable[0] = 0;
for (int i = 1; i < 64; i++)
t->offsettable[i] = 1024;
t->offsettable[31] = 2048;
t->offsettable[32] = 0;
t->offsettable[63] = 2048;
}
static uint32_t half2float(uint16_t h, const Half2FloatTables *t)
{
uint32_t f;
f = t->mantissatable[t->offsettable[h >> 10] + (h & 0x3ff)] + t->exponenttable[h >> 10];
return f;
}
#endif /* AVUTIL_HALF2FLOAT_H */
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