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/*
* jcscale.c
*
* Copyright (C) 1998, Thomas G. Lane.
* This file is part of the Independent JPEG Group's software.
* For conditions of distribution and use, see the accompanying README file.
*
* This file contains sample downscaling by 2^Pt for lossless JPEG.
*/
#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"
#include "jlossls.h" /* Private declarations for lossless codec */
#ifdef C_LOSSLESS_SUPPORTED
METHODDEF(void)
simple_downscale(j_compress_ptr cinfo,
JSAMPROW input_buf, JSAMPROW output_buf, JDIMENSION width)
{
/* j_lossless_c_ptr losslsc = (j_lossless_c_ptr) cinfo->codec; */
unsigned int xindex;
SHIFT_TEMPS
for (xindex = 0; xindex < width; xindex++)
output_buf[xindex] = (JSAMPLE) RIGHT_SHIFT(GETJSAMPLE(input_buf[xindex]),
cinfo->Al);
}
METHODDEF(void)
noscale(j_compress_ptr cinfo,
JSAMPROW input_buf, JSAMPROW output_buf, JDIMENSION width)
{
(void)cinfo;
MEMCOPY(output_buf, input_buf, width * SIZEOF(JSAMPLE));
return;
}
METHODDEF(void)
scaler_start_pass (j_compress_ptr cinfo)
{
j_lossless_c_ptr losslsc = (j_lossless_c_ptr) cinfo->codec;
/* Set scaler function based on Pt */
if (cinfo->Al)
losslsc->scaler_scale = simple_downscale;
else
losslsc->scaler_scale = noscale;
}
GLOBAL(void)
jinit_c_scaler (j_compress_ptr cinfo)
{
j_lossless_c_ptr losslsc = (j_lossless_c_ptr) cinfo->codec;
losslsc->scaler_start_pass = scaler_start_pass;
}
#endif /* C_LOSSLESS_SUPPORTED */
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