74 lines
2.7 KiB
C
74 lines
2.7 KiB
C
/****************************************************************************
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* libs/libnx/nxglib/nxglib_yuv2rgb.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <stdint.h>
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#include <debug.h>
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#include <fixedmath.h>
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#include <nuttx/nx/nxglib.h>
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/****************************************************************************
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* Pre-Processor Definitions
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****************************************************************************/
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#define b16_P3441 0x0000581a /* 0.344147 */
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#define b16_P7141 0x0000b6d2 /* 0.714142 */
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#define b16_1P402 0x000166ea /* 1.402008 */
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#define b16_1P772 0x0001c5a2 /* 1.722003 */
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#define b16_128P0 0x00800000 /* 128.000000 */
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: nxgl_yuv2rgb
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*
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* Description:
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* Convert 8-bit RGB triplet to 8-bit YUV triplet
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*
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****************************************************************************/
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void nxgl_yuv2rgb(uint8_t y, uint8_t u, uint8_t v,
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uint8_t *r, uint8_t *g, uint8_t *b)
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{
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b16_t vm128 = itob16(v) - b16_128P0;
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b16_t um128 = itob16(u) - b16_128P0;
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/* Per the JFIF specification:
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*
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* R = Y + 1.40200 * (V - 128.0)
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* G = Y - 0.34414 * (U - 128.0) - 0.71414 * (V - 128.0)
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* B = Y + 1.77200 * (U - 128.0)
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*/
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*r = (uint8_t)b16toi(itob16(y) +
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b16muli(b16_1P402, vm128));
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*g = (uint8_t)b16toi(itob16(y) - b16muli(b16_P3441, um128) -
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b16muli(b16_P7141, vm128));
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*b = (uint8_t)b16toi(itob16(y) + b16muli(b16_1P772, um128));
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}
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