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74 lines
2.3 KiB
74 lines
2.3 KiB
/* |
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* This file is part of FFmpeg. |
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* |
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* FFmpeg 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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* FFmpeg 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 FFmpeg; 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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#ifndef AVCODEC_HALF2FLOAT_H |
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#define AVCODEC_HALF2FLOAT_H |
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#include <stdint.h> |
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static uint32_t convertmantissa(uint32_t i) |
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{ |
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int32_t m = i << 13; // Zero pad mantissa bits |
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int32_t e = 0; // Zero exponent |
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while (!(m & 0x00800000)) { // While not normalized |
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e -= 0x00800000; // Decrement exponent (1<<23) |
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m <<= 1; // Shift mantissa |
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} |
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m &= ~0x00800000; // Clear leading 1 bit |
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e += 0x38800000; // Adjust bias ((127-14)<<23) |
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return m | e; // Return combined number |
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} |
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static void half2float_table(uint32_t *mantissatable, uint32_t *exponenttable, |
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uint16_t *offsettable) |
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{ |
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mantissatable[0] = 0; |
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for (int i = 1; i < 1024; i++) |
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mantissatable[i] = convertmantissa(i); |
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for (int i = 1024; i < 2048; i++) |
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mantissatable[i] = 0x38000000UL + ((i - 1024) << 13UL); |
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exponenttable[0] = 0; |
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for (int i = 1; i < 31; i++) |
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exponenttable[i] = i << 23; |
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for (int i = 33; i < 63; i++) |
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exponenttable[i] = 0x80000000UL + ((i - 32) << 23UL); |
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exponenttable[31]= 0x47800000UL; |
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exponenttable[32]= 0x80000000UL; |
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exponenttable[63]= 0xC7800000UL; |
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offsettable[0] = 0; |
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for (int i = 1; i < 64; i++) |
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offsettable[i] = 1024; |
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offsettable[32] = 0; |
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} |
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static uint32_t half2float(uint16_t h, const uint32_t *mantissatable, const uint32_t *exponenttable, |
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const uint16_t *offsettable) |
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{ |
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uint32_t f; |
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f = mantissatable[offsettable[h >> 10] + (h & 0x3ff)] + exponenttable[h >> 10]; |
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return f; |
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} |
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#endif /* AVCODEC_HALF2FLOAT_H */
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