/*

 * 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

 */

#include "libavutil/half2float.h"

#if !HAVE_FAST_FLOAT16

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

}

#endif

void ff_init_half2float_tables(Half2FloatTables *t)

{

#if !HAVE_FAST_FLOAT16

    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;

#endif

}