+++ /dev/null
-/*
- * jdscale.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 scaling for lossless JPEG. This is a
- * combination of upscaling the undifferenced sample by 2^Pt and downscaling
- * the sample to fit into JSAMPLE.
- */
-
-#define JPEG_INTERNALS
-#include "jinclude.h"
-#include "jpeglib.h"
-#include "jlossls.h" /* Private declarations for lossless codec */
-
-
-#ifdef D_LOSSLESS_SUPPORTED
-
-/*
- * Private scaler object for lossless decoding.
- */
-
-typedef struct {
- int scale_factor;
-} scaler;
-
-typedef scaler * scaler_ptr;
-
-
-/*
- * Scalers for packing sample differences into JSAMPLEs.
- */
-
-METHODDEF(void)
-simple_upscale(j_decompress_ptr cinfo,
- JDIFFROW diff_buf, JSAMPROW output_buf,
- JDIMENSION width)
-{
- j_lossless_d_ptr losslsd = (j_lossless_d_ptr) cinfo->codec;
- scaler_ptr scaler = (scaler_ptr) losslsd->scaler_private;
- int scale_factor = scaler->scale_factor;
- unsigned int xindex;
-
- for (xindex = 0; xindex < width; xindex++)
- output_buf[xindex] = (JSAMPLE) (diff_buf[xindex] << scale_factor);
-}
-
-METHODDEF(void)
-simple_downscale(j_decompress_ptr cinfo,
- JDIFFROW diff_buf, JSAMPROW output_buf,
- JDIMENSION width)
-{
- j_lossless_d_ptr losslsd = (j_lossless_d_ptr) cinfo->codec;
- scaler_ptr scaler = (scaler_ptr) losslsd->scaler_private;
- int scale_factor = scaler->scale_factor;
- unsigned int xindex;
- SHIFT_TEMPS
-
- for (xindex = 0; xindex < width; xindex++)
- output_buf[xindex] = (JSAMPLE) RIGHT_SHIFT(diff_buf[xindex], scale_factor);
-}
-
-METHODDEF(void)
-noscale(j_decompress_ptr cinfo,
- JDIFFROW diff_buf, JSAMPROW output_buf,
- JDIMENSION width)
-{
- unsigned int xindex;
- (void)cinfo;
-
- for (xindex = 0; xindex < width; xindex++)
- output_buf[xindex] = (JSAMPLE) diff_buf[xindex];
-}
-
-
-METHODDEF(void)
-scaler_start_pass (j_decompress_ptr cinfo)
-{
- j_lossless_d_ptr losslsd = (j_lossless_d_ptr) cinfo->codec;
- scaler_ptr scaler = (scaler_ptr) losslsd->scaler_private;
- int downscale;
-
- /*
- * Downscale by the difference in the input vs. output precision. If the
- * output precision >= input precision, then do not downscale.
- */
- downscale = BITS_IN_JSAMPLE < cinfo->data_precision ?
- cinfo->data_precision - BITS_IN_JSAMPLE : 0;
-
- scaler->scale_factor = cinfo->Al - downscale;
-
- /* Set scaler functions based on scale_factor (positive = left shift) */
- if (scaler->scale_factor > 0)
- losslsd->scaler_scale = simple_upscale;
- else if (scaler->scale_factor < 0) {
- scaler->scale_factor = -scaler->scale_factor;
- losslsd->scaler_scale = simple_downscale;
- }
- else
- losslsd->scaler_scale = noscale;
-}
-
-
-GLOBAL(void)
-jinit_d_scaler (j_decompress_ptr cinfo)
-{
- j_lossless_d_ptr losslsd = (j_lossless_d_ptr) cinfo->codec;
- scaler_ptr scaler;
-
- scaler = (scaler_ptr)
- (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
- SIZEOF(scaler));
- losslsd->scaler_private = (void *) scaler;
- losslsd->scaler_start_pass = scaler_start_pass;
-}
-
-#endif /* D_LOSSLESS_SUPPORTED */
-