102 lines
4.2 KiB
C
102 lines
4.2 KiB
C
/****************************************************************************
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* graphics/color/nxglib_yuv2rgb.c
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*
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* Copyright (C) 2008 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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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 <sys/types.h>
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#include <debug.h>
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#include <fixedmath.h>
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#include <nuttx/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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* Private Types
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****************************************************************************/
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/****************************************************************************
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* Private Function Prototypes
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****************************************************************************/
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/****************************************************************************
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* Private Data
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****************************************************************************/
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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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(ubyte y, ubyte u, ubyte v, ubyte *r, ubyte *g, ubyte *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 = (ubyte)b16toi(itob16(y) + b16muli(b16_1P402, vm128));
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*g = (ubyte)b16toi(itob16(y) - b16muli(b16_P3441, um128) - b16muli(b16_P7141, vm128));
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*b = (ubyte)b16toi(itob16(y) + b16muli(b16_1P772, um128));
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}
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