FFmpeg: libavutil/half2float.c Source File

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libavutil

half2float.c

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1 /*

2 * This file is part of FFmpeg.

3 *

4 * FFmpeg is free software; you can redistribute it and/or

5 * modify it under the terms of the GNU Lesser General Public

6 * License as published by the Free Software Foundation; either

7 * version 2.1 of the License, or (at your option) any later version.

8 *

9 * FFmpeg is distributed in the hope that it will be useful,

10 * but WITHOUT ANY WARRANTY; without even the implied warranty of

11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU

12 * Lesser General Public License for more details.

13 *

14 * You should have received a copy of the GNU Lesser General Public

15 * License along with FFmpeg; if not, write to the Free Software

16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

17 */

19 #include "libavutil/half2float.h"

21 #if !HAVE_FAST_FLOAT16

22 static uint32_t convertmantissa(uint32_t i)

23 {

24 int32_t m = i << 13; // Zero pad mantissa bits

25 int32_t e = 0; // Zero exponent

27 while (!(m & 0x00800000)) { // While not normalized

28 e -= 0x00800000; // Decrement exponent (1<<23)

29 m <<= 1; // Shift mantissa

30 }

32 m &= ~0x00800000; // Clear leading 1 bit

33 e += 0x38800000; // Adjust bias ((127-14)<<23)

35 return m | e; // Return combined number

36 }

37 #endif

39 void ff_init_half2float_tables(Half2FloatTables *t)

40 {

41 #if !HAVE_FAST_FLOAT16

42 t->mantissatable[0] = 0;

43 for (int i = 1; i < 1024; i++)

44 t->mantissatable[i] = convertmantissa(i);

45 for (int i = 1024; i < 2048; i++)

46 t->mantissatable[i] = 0x38000000UL + ((i - 1024) << 13UL);

47 for (int i = 2048; i < 3072; i++)

48 t->mantissatable[i] = t->mantissatable[i - 1024] | 0x400000UL;

49 t->mantissatable[2048] = t->mantissatable[1024];

51 t->exponenttable[0] = 0;

52 for (int i = 1; i < 31; i++)

53 t->exponenttable[i] = i << 23;

54 for (int i = 33; i < 63; i++)

55 t->exponenttable[i] = 0x80000000UL + ((i - 32) << 23UL);

56 t->exponenttable[31]= 0x47800000UL;

57 t->exponenttable[32]= 0x80000000UL;

58 t->exponenttable[63]= 0xC7800000UL;

60 t->offsettable[0] = 0;

61 for (int i = 1; i < 64; i++)

62 t->offsettable[i] = 1024;

63 t->offsettable[31] = 2048;

64 t->offsettable[32] = 0;

65 t->offsettable[63] = 2048;

66 #endif

67 }

Half2FloatTables

Definition: half2float.h:27

convertmantissa

static uint32_t convertmantissa(uint32_t i)

Definition: half2float.c:22

Half2FloatTables::offsettable

uint16_t offsettable[64]

Definition: half2float.h:33

for

for(k=2;k<=8;++k)

Definition: h264pred_template.c:425

half2float.h

#define i(width, name, range_min, range_max)

Definition: cbs_h2645.c:256

ff_init_half2float_tables

void ff_init_half2float_tables(Half2FloatTables *t)

Definition: half2float.c:39

Half2FloatTables::exponenttable

uint32_t exponenttable[64]

Definition: half2float.h:32

Half2FloatTables::mantissatable

uint32_t mantissatable[3072]

Definition: half2float.h:31

int32_t

Definition: audioconvert.c:56

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