michael@0: /*
michael@0:  * jdmaster.c
michael@0:  *
michael@0:  * This file was part of the Independent JPEG Group's software:
michael@0:  * Copyright (C) 1991-1997, Thomas G. Lane.
michael@0:  * Modified 2002-2009 by Guido Vollbeding.
michael@0:  * libjpeg-turbo Modifications:
michael@0:  * Copyright (C) 2009-2011, D. R. Commander.
michael@0:  * For conditions of distribution and use, see the accompanying README file.
michael@0:  *
michael@0:  * This file contains master control logic for the JPEG decompressor.
michael@0:  * These routines are concerned with selecting the modules to be executed
michael@0:  * and with determining the number of passes and the work to be done in each
michael@0:  * pass.
michael@0:  */
michael@0: 
michael@0: #define JPEG_INTERNALS
michael@0: #include "jinclude.h"
michael@0: #include "jpeglib.h"
michael@0: #include "jpegcomp.h"
michael@0: 
michael@0: 
michael@0: /* Private state */
michael@0: 
michael@0: typedef struct {
michael@0:   struct jpeg_decomp_master pub; /* public fields */
michael@0: 
michael@0:   int pass_number;		/* # of passes completed */
michael@0: 
michael@0:   boolean using_merged_upsample; /* TRUE if using merged upsample/cconvert */
michael@0: 
michael@0:   /* Saved references to initialized quantizer modules,
michael@0:    * in case we need to switch modes.
michael@0:    */
michael@0:   struct jpeg_color_quantizer * quantizer_1pass;
michael@0:   struct jpeg_color_quantizer * quantizer_2pass;
michael@0: } my_decomp_master;
michael@0: 
michael@0: typedef my_decomp_master * my_master_ptr;
michael@0: 
michael@0: 
michael@0: /*
michael@0:  * Determine whether merged upsample/color conversion should be used.
michael@0:  * CRUCIAL: this must match the actual capabilities of jdmerge.c!
michael@0:  */
michael@0: 
michael@0: LOCAL(boolean)
michael@0: use_merged_upsample (j_decompress_ptr cinfo)
michael@0: {
michael@0: #ifdef UPSAMPLE_MERGING_SUPPORTED
michael@0:   /* Merging is the equivalent of plain box-filter upsampling */
michael@0:   if (cinfo->do_fancy_upsampling || cinfo->CCIR601_sampling)
michael@0:     return FALSE;
michael@0:   /* jdmerge.c only supports YCC=>RGB color conversion */
michael@0:   if (cinfo->jpeg_color_space != JCS_YCbCr || cinfo->num_components != 3 ||
michael@0:       (cinfo->out_color_space != JCS_RGB &&
michael@0:       cinfo->out_color_space != JCS_EXT_RGB &&
michael@0:       cinfo->out_color_space != JCS_EXT_RGBX &&
michael@0:       cinfo->out_color_space != JCS_EXT_BGR &&
michael@0:       cinfo->out_color_space != JCS_EXT_BGRX &&
michael@0:       cinfo->out_color_space != JCS_EXT_XBGR &&
michael@0:       cinfo->out_color_space != JCS_EXT_XRGB &&
michael@0:       cinfo->out_color_space != JCS_EXT_RGBA &&
michael@0:       cinfo->out_color_space != JCS_EXT_BGRA &&
michael@0:       cinfo->out_color_space != JCS_EXT_ABGR &&
michael@0:       cinfo->out_color_space != JCS_EXT_ARGB) ||
michael@0:       cinfo->out_color_components != rgb_pixelsize[cinfo->out_color_space])
michael@0:     return FALSE;
michael@0:   /* and it only handles 2h1v or 2h2v sampling ratios */
michael@0:   if (cinfo->comp_info[0].h_samp_factor != 2 ||
michael@0:       cinfo->comp_info[1].h_samp_factor != 1 ||
michael@0:       cinfo->comp_info[2].h_samp_factor != 1 ||
michael@0:       cinfo->comp_info[0].v_samp_factor >  2 ||
michael@0:       cinfo->comp_info[1].v_samp_factor != 1 ||
michael@0:       cinfo->comp_info[2].v_samp_factor != 1)
michael@0:     return FALSE;
michael@0:   /* furthermore, it doesn't work if we've scaled the IDCTs differently */
michael@0:   if (cinfo->comp_info[0]._DCT_scaled_size != cinfo->_min_DCT_scaled_size ||
michael@0:       cinfo->comp_info[1]._DCT_scaled_size != cinfo->_min_DCT_scaled_size ||
michael@0:       cinfo->comp_info[2]._DCT_scaled_size != cinfo->_min_DCT_scaled_size)
michael@0:     return FALSE;
michael@0:   /* ??? also need to test for upsample-time rescaling, when & if supported */
michael@0:   return TRUE;			/* by golly, it'll work... */
michael@0: #else
michael@0:   return FALSE;
michael@0: #endif
michael@0: }
michael@0: 
michael@0: 
michael@0: /*
michael@0:  * Compute output image dimensions and related values.
michael@0:  * NOTE: this is exported for possible use by application.
michael@0:  * Hence it mustn't do anything that can't be done twice.
michael@0:  */
michael@0: 
michael@0: #if JPEG_LIB_VERSION >= 80
michael@0: GLOBAL(void)
michael@0: #else
michael@0: LOCAL(void)
michael@0: #endif
michael@0: jpeg_core_output_dimensions (j_decompress_ptr cinfo)
michael@0: /* Do computations that are needed before master selection phase.
michael@0:  * This function is used for transcoding and full decompression.
michael@0:  */
michael@0: {
michael@0: #ifdef IDCT_SCALING_SUPPORTED
michael@0:   int ci;
michael@0:   jpeg_component_info *compptr;
michael@0: 
michael@0:   /* Compute actual output image dimensions and DCT scaling choices. */
michael@0:   if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom) {
michael@0:     /* Provide 1/block_size scaling */
michael@0:     cinfo->output_width = (JDIMENSION)
michael@0:       jdiv_round_up((long) cinfo->image_width, (long) DCTSIZE);
michael@0:     cinfo->output_height = (JDIMENSION)
michael@0:       jdiv_round_up((long) cinfo->image_height, (long) DCTSIZE);
michael@0:     cinfo->_min_DCT_h_scaled_size = 1;
michael@0:     cinfo->_min_DCT_v_scaled_size = 1;
michael@0:   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 2) {
michael@0:     /* Provide 2/block_size scaling */
michael@0:     cinfo->output_width = (JDIMENSION)
michael@0:       jdiv_round_up((long) cinfo->image_width * 2L, (long) DCTSIZE);
michael@0:     cinfo->output_height = (JDIMENSION)
michael@0:       jdiv_round_up((long) cinfo->image_height * 2L, (long) DCTSIZE);
michael@0:     cinfo->_min_DCT_h_scaled_size = 2;
michael@0:     cinfo->_min_DCT_v_scaled_size = 2;
michael@0:   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 3) {
michael@0:     /* Provide 3/block_size scaling */
michael@0:     cinfo->output_width = (JDIMENSION)
michael@0:       jdiv_round_up((long) cinfo->image_width * 3L, (long) DCTSIZE);
michael@0:     cinfo->output_height = (JDIMENSION)
michael@0:       jdiv_round_up((long) cinfo->image_height * 3L, (long) DCTSIZE);
michael@0:     cinfo->_min_DCT_h_scaled_size = 3;
michael@0:     cinfo->_min_DCT_v_scaled_size = 3;
michael@0:   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 4) {
michael@0:     /* Provide 4/block_size scaling */
michael@0:     cinfo->output_width = (JDIMENSION)
michael@0:       jdiv_round_up((long) cinfo->image_width * 4L, (long) DCTSIZE);
michael@0:     cinfo->output_height = (JDIMENSION)
michael@0:       jdiv_round_up((long) cinfo->image_height * 4L, (long) DCTSIZE);
michael@0:     cinfo->_min_DCT_h_scaled_size = 4;
michael@0:     cinfo->_min_DCT_v_scaled_size = 4;
michael@0:   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 5) {
michael@0:     /* Provide 5/block_size scaling */
michael@0:     cinfo->output_width = (JDIMENSION)
michael@0:       jdiv_round_up((long) cinfo->image_width * 5L, (long) DCTSIZE);
michael@0:     cinfo->output_height = (JDIMENSION)
michael@0:       jdiv_round_up((long) cinfo->image_height * 5L, (long) DCTSIZE);
michael@0:     cinfo->_min_DCT_h_scaled_size = 5;
michael@0:     cinfo->_min_DCT_v_scaled_size = 5;
michael@0:   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 6) {
michael@0:     /* Provide 6/block_size scaling */
michael@0:     cinfo->output_width = (JDIMENSION)
michael@0:       jdiv_round_up((long) cinfo->image_width * 6L, (long) DCTSIZE);
michael@0:     cinfo->output_height = (JDIMENSION)
michael@0:       jdiv_round_up((long) cinfo->image_height * 6L, (long) DCTSIZE);
michael@0:     cinfo->_min_DCT_h_scaled_size = 6;
michael@0:     cinfo->_min_DCT_v_scaled_size = 6;
michael@0:   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 7) {
michael@0:     /* Provide 7/block_size scaling */
michael@0:     cinfo->output_width = (JDIMENSION)
michael@0:       jdiv_round_up((long) cinfo->image_width * 7L, (long) DCTSIZE);
michael@0:     cinfo->output_height = (JDIMENSION)
michael@0:       jdiv_round_up((long) cinfo->image_height * 7L, (long) DCTSIZE);
michael@0:     cinfo->_min_DCT_h_scaled_size = 7;
michael@0:     cinfo->_min_DCT_v_scaled_size = 7;
michael@0:   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 8) {
michael@0:     /* Provide 8/block_size scaling */
michael@0:     cinfo->output_width = (JDIMENSION)
michael@0:       jdiv_round_up((long) cinfo->image_width * 8L, (long) DCTSIZE);
michael@0:     cinfo->output_height = (JDIMENSION)
michael@0:       jdiv_round_up((long) cinfo->image_height * 8L, (long) DCTSIZE);
michael@0:     cinfo->_min_DCT_h_scaled_size = 8;
michael@0:     cinfo->_min_DCT_v_scaled_size = 8;
michael@0:   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 9) {
michael@0:     /* Provide 9/block_size scaling */
michael@0:     cinfo->output_width = (JDIMENSION)
michael@0:       jdiv_round_up((long) cinfo->image_width * 9L, (long) DCTSIZE);
michael@0:     cinfo->output_height = (JDIMENSION)
michael@0:       jdiv_round_up((long) cinfo->image_height * 9L, (long) DCTSIZE);
michael@0:     cinfo->_min_DCT_h_scaled_size = 9;
michael@0:     cinfo->_min_DCT_v_scaled_size = 9;
michael@0:   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 10) {
michael@0:     /* Provide 10/block_size scaling */
michael@0:     cinfo->output_width = (JDIMENSION)
michael@0:       jdiv_round_up((long) cinfo->image_width * 10L, (long) DCTSIZE);
michael@0:     cinfo->output_height = (JDIMENSION)
michael@0:       jdiv_round_up((long) cinfo->image_height * 10L, (long) DCTSIZE);
michael@0:     cinfo->_min_DCT_h_scaled_size = 10;
michael@0:     cinfo->_min_DCT_v_scaled_size = 10;
michael@0:   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 11) {
michael@0:     /* Provide 11/block_size scaling */
michael@0:     cinfo->output_width = (JDIMENSION)
michael@0:       jdiv_round_up((long) cinfo->image_width * 11L, (long) DCTSIZE);
michael@0:     cinfo->output_height = (JDIMENSION)
michael@0:       jdiv_round_up((long) cinfo->image_height * 11L, (long) DCTSIZE);
michael@0:     cinfo->_min_DCT_h_scaled_size = 11;
michael@0:     cinfo->_min_DCT_v_scaled_size = 11;
michael@0:   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 12) {
michael@0:     /* Provide 12/block_size scaling */
michael@0:     cinfo->output_width = (JDIMENSION)
michael@0:       jdiv_round_up((long) cinfo->image_width * 12L, (long) DCTSIZE);
michael@0:     cinfo->output_height = (JDIMENSION)
michael@0:       jdiv_round_up((long) cinfo->image_height * 12L, (long) DCTSIZE);
michael@0:     cinfo->_min_DCT_h_scaled_size = 12;
michael@0:     cinfo->_min_DCT_v_scaled_size = 12;
michael@0:   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 13) {
michael@0:     /* Provide 13/block_size scaling */
michael@0:     cinfo->output_width = (JDIMENSION)
michael@0:       jdiv_round_up((long) cinfo->image_width * 13L, (long) DCTSIZE);
michael@0:     cinfo->output_height = (JDIMENSION)
michael@0:       jdiv_round_up((long) cinfo->image_height * 13L, (long) DCTSIZE);
michael@0:     cinfo->_min_DCT_h_scaled_size = 13;
michael@0:     cinfo->_min_DCT_v_scaled_size = 13;
michael@0:   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 14) {
michael@0:     /* Provide 14/block_size scaling */
michael@0:     cinfo->output_width = (JDIMENSION)
michael@0:       jdiv_round_up((long) cinfo->image_width * 14L, (long) DCTSIZE);
michael@0:     cinfo->output_height = (JDIMENSION)
michael@0:       jdiv_round_up((long) cinfo->image_height * 14L, (long) DCTSIZE);
michael@0:     cinfo->_min_DCT_h_scaled_size = 14;
michael@0:     cinfo->_min_DCT_v_scaled_size = 14;
michael@0:   } else if (cinfo->scale_num * DCTSIZE <= cinfo->scale_denom * 15) {
michael@0:     /* Provide 15/block_size scaling */
michael@0:     cinfo->output_width = (JDIMENSION)
michael@0:       jdiv_round_up((long) cinfo->image_width * 15L, (long) DCTSIZE);
michael@0:     cinfo->output_height = (JDIMENSION)
michael@0:       jdiv_round_up((long) cinfo->image_height * 15L, (long) DCTSIZE);
michael@0:     cinfo->_min_DCT_h_scaled_size = 15;
michael@0:     cinfo->_min_DCT_v_scaled_size = 15;
michael@0:   } else {
michael@0:     /* Provide 16/block_size scaling */
michael@0:     cinfo->output_width = (JDIMENSION)
michael@0:       jdiv_round_up((long) cinfo->image_width * 16L, (long) DCTSIZE);
michael@0:     cinfo->output_height = (JDIMENSION)
michael@0:       jdiv_round_up((long) cinfo->image_height * 16L, (long) DCTSIZE);
michael@0:     cinfo->_min_DCT_h_scaled_size = 16;
michael@0:     cinfo->_min_DCT_v_scaled_size = 16;
michael@0:   }
michael@0: 
michael@0:   /* Recompute dimensions of components */
michael@0:   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
michael@0:        ci++, compptr++) {
michael@0:     compptr->_DCT_h_scaled_size = cinfo->_min_DCT_h_scaled_size;
michael@0:     compptr->_DCT_v_scaled_size = cinfo->_min_DCT_v_scaled_size;
michael@0:   }
michael@0: 
michael@0: #else /* !IDCT_SCALING_SUPPORTED */
michael@0: 
michael@0:   /* Hardwire it to "no scaling" */
michael@0:   cinfo->output_width = cinfo->image_width;
michael@0:   cinfo->output_height = cinfo->image_height;
michael@0:   /* jdinput.c has already initialized DCT_scaled_size,
michael@0:    * and has computed unscaled downsampled_width and downsampled_height.
michael@0:    */
michael@0: 
michael@0: #endif /* IDCT_SCALING_SUPPORTED */
michael@0: }
michael@0: 
michael@0: 
michael@0: /*
michael@0:  * Compute output image dimensions and related values.
michael@0:  * NOTE: this is exported for possible use by application.
michael@0:  * Hence it mustn't do anything that can't be done twice.
michael@0:  * Also note that it may be called before the master module is initialized!
michael@0:  */
michael@0: 
michael@0: GLOBAL(void)
michael@0: jpeg_calc_output_dimensions (j_decompress_ptr cinfo)
michael@0: /* Do computations that are needed before master selection phase */
michael@0: {
michael@0: #ifdef IDCT_SCALING_SUPPORTED
michael@0:   int ci;
michael@0:   jpeg_component_info *compptr;
michael@0: #endif
michael@0: 
michael@0:   /* Prevent application from calling me at wrong times */
michael@0:   if (cinfo->global_state != DSTATE_READY)
michael@0:     ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
michael@0: 
michael@0:   /* Compute core output image dimensions and DCT scaling choices. */
michael@0:   jpeg_core_output_dimensions(cinfo);
michael@0: 
michael@0: #ifdef IDCT_SCALING_SUPPORTED
michael@0: 
michael@0:   /* In selecting the actual DCT scaling for each component, we try to
michael@0:    * scale up the chroma components via IDCT scaling rather than upsampling.
michael@0:    * This saves time if the upsampler gets to use 1:1 scaling.
michael@0:    * Note this code adapts subsampling ratios which are powers of 2.
michael@0:    */
michael@0:   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
michael@0:        ci++, compptr++) {
michael@0:     int ssize = cinfo->_min_DCT_scaled_size;
michael@0:     while (ssize < DCTSIZE &&
michael@0: 	   ((cinfo->max_h_samp_factor * cinfo->_min_DCT_scaled_size) %
michael@0: 	    (compptr->h_samp_factor * ssize * 2) == 0) &&
michael@0: 	   ((cinfo->max_v_samp_factor * cinfo->_min_DCT_scaled_size) %
michael@0: 	    (compptr->v_samp_factor * ssize * 2) == 0)) {
michael@0:       ssize = ssize * 2;
michael@0:     }
michael@0: #if JPEG_LIB_VERSION >= 70
michael@0:     compptr->DCT_h_scaled_size = compptr->DCT_v_scaled_size = ssize;
michael@0: #else
michael@0:     compptr->DCT_scaled_size = ssize;
michael@0: #endif
michael@0:   }
michael@0: 
michael@0:   /* Recompute downsampled dimensions of components;
michael@0:    * application needs to know these if using raw downsampled data.
michael@0:    */
michael@0:   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
michael@0:        ci++, compptr++) {
michael@0:     /* Size in samples, after IDCT scaling */
michael@0:     compptr->downsampled_width = (JDIMENSION)
michael@0:       jdiv_round_up((long) cinfo->image_width *
michael@0: 		    (long) (compptr->h_samp_factor * compptr->_DCT_scaled_size),
michael@0: 		    (long) (cinfo->max_h_samp_factor * DCTSIZE));
michael@0:     compptr->downsampled_height = (JDIMENSION)
michael@0:       jdiv_round_up((long) cinfo->image_height *
michael@0: 		    (long) (compptr->v_samp_factor * compptr->_DCT_scaled_size),
michael@0: 		    (long) (cinfo->max_v_samp_factor * DCTSIZE));
michael@0:   }
michael@0: 
michael@0: #else /* !IDCT_SCALING_SUPPORTED */
michael@0: 
michael@0:   /* Hardwire it to "no scaling" */
michael@0:   cinfo->output_width = cinfo->image_width;
michael@0:   cinfo->output_height = cinfo->image_height;
michael@0:   /* jdinput.c has already initialized DCT_scaled_size to DCTSIZE,
michael@0:    * and has computed unscaled downsampled_width and downsampled_height.
michael@0:    */
michael@0: 
michael@0: #endif /* IDCT_SCALING_SUPPORTED */
michael@0: 
michael@0:   /* Report number of components in selected colorspace. */
michael@0:   /* Probably this should be in the color conversion module... */
michael@0:   switch (cinfo->out_color_space) {
michael@0:   case JCS_GRAYSCALE:
michael@0:     cinfo->out_color_components = 1;
michael@0:     break;
michael@0:   case JCS_RGB:
michael@0:   case JCS_EXT_RGB:
michael@0:   case JCS_EXT_RGBX:
michael@0:   case JCS_EXT_BGR:
michael@0:   case JCS_EXT_BGRX:
michael@0:   case JCS_EXT_XBGR:
michael@0:   case JCS_EXT_XRGB:
michael@0:   case JCS_EXT_RGBA:
michael@0:   case JCS_EXT_BGRA:
michael@0:   case JCS_EXT_ABGR:
michael@0:   case JCS_EXT_ARGB:
michael@0:     cinfo->out_color_components = rgb_pixelsize[cinfo->out_color_space];
michael@0:     break;
michael@0:   case JCS_YCbCr:
michael@0:     cinfo->out_color_components = 3;
michael@0:     break;
michael@0:   case JCS_CMYK:
michael@0:   case JCS_YCCK:
michael@0:     cinfo->out_color_components = 4;
michael@0:     break;
michael@0:   default:			/* else must be same colorspace as in file */
michael@0:     cinfo->out_color_components = cinfo->num_components;
michael@0:     break;
michael@0:   }
michael@0:   cinfo->output_components = (cinfo->quantize_colors ? 1 :
michael@0: 			      cinfo->out_color_components);
michael@0: 
michael@0:   /* See if upsampler will want to emit more than one row at a time */
michael@0:   if (use_merged_upsample(cinfo))
michael@0:     cinfo->rec_outbuf_height = cinfo->max_v_samp_factor;
michael@0:   else
michael@0:     cinfo->rec_outbuf_height = 1;
michael@0: }
michael@0: 
michael@0: 
michael@0: /*
michael@0:  * Several decompression processes need to range-limit values to the range
michael@0:  * 0..MAXJSAMPLE; the input value may fall somewhat outside this range
michael@0:  * due to noise introduced by quantization, roundoff error, etc.  These
michael@0:  * processes are inner loops and need to be as fast as possible.  On most
michael@0:  * machines, particularly CPUs with pipelines or instruction prefetch,
michael@0:  * a (subscript-check-less) C table lookup
michael@0:  *		x = sample_range_limit[x];
michael@0:  * is faster than explicit tests
michael@0:  *		if (x < 0)  x = 0;
michael@0:  *		else if (x > MAXJSAMPLE)  x = MAXJSAMPLE;
michael@0:  * These processes all use a common table prepared by the routine below.
michael@0:  *
michael@0:  * For most steps we can mathematically guarantee that the initial value
michael@0:  * of x is within MAXJSAMPLE+1 of the legal range, so a table running from
michael@0:  * -(MAXJSAMPLE+1) to 2*MAXJSAMPLE+1 is sufficient.  But for the initial
michael@0:  * limiting step (just after the IDCT), a wildly out-of-range value is 
michael@0:  * possible if the input data is corrupt.  To avoid any chance of indexing
michael@0:  * off the end of memory and getting a bad-pointer trap, we perform the
michael@0:  * post-IDCT limiting thus:
michael@0:  *		x = range_limit[x & MASK];
michael@0:  * where MASK is 2 bits wider than legal sample data, ie 10 bits for 8-bit
michael@0:  * samples.  Under normal circumstances this is more than enough range and
michael@0:  * a correct output will be generated; with bogus input data the mask will
michael@0:  * cause wraparound, and we will safely generate a bogus-but-in-range output.
michael@0:  * For the post-IDCT step, we want to convert the data from signed to unsigned
michael@0:  * representation by adding CENTERJSAMPLE at the same time that we limit it.
michael@0:  * So the post-IDCT limiting table ends up looking like this:
michael@0:  *   CENTERJSAMPLE,CENTERJSAMPLE+1,...,MAXJSAMPLE,
michael@0:  *   MAXJSAMPLE (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
michael@0:  *   0          (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
michael@0:  *   0,1,...,CENTERJSAMPLE-1
michael@0:  * Negative inputs select values from the upper half of the table after
michael@0:  * masking.
michael@0:  *
michael@0:  * We can save some space by overlapping the start of the post-IDCT table
michael@0:  * with the simpler range limiting table.  The post-IDCT table begins at
michael@0:  * sample_range_limit + CENTERJSAMPLE.
michael@0:  *
michael@0:  * Note that the table is allocated in near data space on PCs; it's small
michael@0:  * enough and used often enough to justify this.
michael@0:  */
michael@0: 
michael@0: LOCAL(void)
michael@0: prepare_range_limit_table (j_decompress_ptr cinfo)
michael@0: /* Allocate and fill in the sample_range_limit table */
michael@0: {
michael@0:   JSAMPLE * table;
michael@0:   int i;
michael@0: 
michael@0:   table = (JSAMPLE *)
michael@0:     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
michael@0: 		(5 * (MAXJSAMPLE+1) + CENTERJSAMPLE) * SIZEOF(JSAMPLE));
michael@0:   table += (MAXJSAMPLE+1);	/* allow negative subscripts of simple table */
michael@0:   cinfo->sample_range_limit = table;
michael@0:   /* First segment of "simple" table: limit[x] = 0 for x < 0 */
michael@0:   MEMZERO(table - (MAXJSAMPLE+1), (MAXJSAMPLE+1) * SIZEOF(JSAMPLE));
michael@0:   /* Main part of "simple" table: limit[x] = x */
michael@0:   for (i = 0; i <= MAXJSAMPLE; i++)
michael@0:     table[i] = (JSAMPLE) i;
michael@0:   table += CENTERJSAMPLE;	/* Point to where post-IDCT table starts */
michael@0:   /* End of simple table, rest of first half of post-IDCT table */
michael@0:   for (i = CENTERJSAMPLE; i < 2*(MAXJSAMPLE+1); i++)
michael@0:     table[i] = MAXJSAMPLE;
michael@0:   /* Second half of post-IDCT table */
michael@0:   MEMZERO(table + (2 * (MAXJSAMPLE+1)),
michael@0: 	  (2 * (MAXJSAMPLE+1) - CENTERJSAMPLE) * SIZEOF(JSAMPLE));
michael@0:   MEMCOPY(table + (4 * (MAXJSAMPLE+1) - CENTERJSAMPLE),
michael@0: 	  cinfo->sample_range_limit, CENTERJSAMPLE * SIZEOF(JSAMPLE));
michael@0: }
michael@0: 
michael@0: 
michael@0: /*
michael@0:  * Master selection of decompression modules.
michael@0:  * This is done once at jpeg_start_decompress time.  We determine
michael@0:  * which modules will be used and give them appropriate initialization calls.
michael@0:  * We also initialize the decompressor input side to begin consuming data.
michael@0:  *
michael@0:  * Since jpeg_read_header has finished, we know what is in the SOF
michael@0:  * and (first) SOS markers.  We also have all the application parameter
michael@0:  * settings.
michael@0:  */
michael@0: 
michael@0: LOCAL(void)
michael@0: master_selection (j_decompress_ptr cinfo)
michael@0: {
michael@0:   my_master_ptr master = (my_master_ptr) cinfo->master;
michael@0:   boolean use_c_buffer;
michael@0:   long samplesperrow;
michael@0:   JDIMENSION jd_samplesperrow;
michael@0: 
michael@0:   /* Initialize dimensions and other stuff */
michael@0:   jpeg_calc_output_dimensions(cinfo);
michael@0:   prepare_range_limit_table(cinfo);
michael@0: 
michael@0:   /* Width of an output scanline must be representable as JDIMENSION. */
michael@0:   samplesperrow = (long) cinfo->output_width * (long) cinfo->out_color_components;
michael@0:   jd_samplesperrow = (JDIMENSION) samplesperrow;
michael@0:   if ((long) jd_samplesperrow != samplesperrow)
michael@0:     ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);
michael@0: 
michael@0:   /* Initialize my private state */
michael@0:   master->pass_number = 0;
michael@0:   master->using_merged_upsample = use_merged_upsample(cinfo);
michael@0: 
michael@0:   /* Color quantizer selection */
michael@0:   master->quantizer_1pass = NULL;
michael@0:   master->quantizer_2pass = NULL;
michael@0:   /* No mode changes if not using buffered-image mode. */
michael@0:   if (! cinfo->quantize_colors || ! cinfo->buffered_image) {
michael@0:     cinfo->enable_1pass_quant = FALSE;
michael@0:     cinfo->enable_external_quant = FALSE;
michael@0:     cinfo->enable_2pass_quant = FALSE;
michael@0:   }
michael@0:   if (cinfo->quantize_colors) {
michael@0:     if (cinfo->raw_data_out)
michael@0:       ERREXIT(cinfo, JERR_NOTIMPL);
michael@0:     /* 2-pass quantizer only works in 3-component color space. */
michael@0:     if (cinfo->out_color_components != 3) {
michael@0:       cinfo->enable_1pass_quant = TRUE;
michael@0:       cinfo->enable_external_quant = FALSE;
michael@0:       cinfo->enable_2pass_quant = FALSE;
michael@0:       cinfo->colormap = NULL;
michael@0:     } else if (cinfo->colormap != NULL) {
michael@0:       cinfo->enable_external_quant = TRUE;
michael@0:     } else if (cinfo->two_pass_quantize) {
michael@0:       cinfo->enable_2pass_quant = TRUE;
michael@0:     } else {
michael@0:       cinfo->enable_1pass_quant = TRUE;
michael@0:     }
michael@0: 
michael@0:     if (cinfo->enable_1pass_quant) {
michael@0: #ifdef QUANT_1PASS_SUPPORTED
michael@0:       jinit_1pass_quantizer(cinfo);
michael@0:       master->quantizer_1pass = cinfo->cquantize;
michael@0: #else
michael@0:       ERREXIT(cinfo, JERR_NOT_COMPILED);
michael@0: #endif
michael@0:     }
michael@0: 
michael@0:     /* We use the 2-pass code to map to external colormaps. */
michael@0:     if (cinfo->enable_2pass_quant || cinfo->enable_external_quant) {
michael@0: #ifdef QUANT_2PASS_SUPPORTED
michael@0:       jinit_2pass_quantizer(cinfo);
michael@0:       master->quantizer_2pass = cinfo->cquantize;
michael@0: #else
michael@0:       ERREXIT(cinfo, JERR_NOT_COMPILED);
michael@0: #endif
michael@0:     }
michael@0:     /* If both quantizers are initialized, the 2-pass one is left active;
michael@0:      * this is necessary for starting with quantization to an external map.
michael@0:      */
michael@0:   }
michael@0: 
michael@0:   /* Post-processing: in particular, color conversion first */
michael@0:   if (! cinfo->raw_data_out) {
michael@0:     if (master->using_merged_upsample) {
michael@0: #ifdef UPSAMPLE_MERGING_SUPPORTED
michael@0:       jinit_merged_upsampler(cinfo); /* does color conversion too */
michael@0: #else
michael@0:       ERREXIT(cinfo, JERR_NOT_COMPILED);
michael@0: #endif
michael@0:     } else {
michael@0:       jinit_color_deconverter(cinfo);
michael@0:       jinit_upsampler(cinfo);
michael@0:     }
michael@0:     jinit_d_post_controller(cinfo, cinfo->enable_2pass_quant);
michael@0:   }
michael@0:   /* Inverse DCT */
michael@0:   jinit_inverse_dct(cinfo);
michael@0:   /* Entropy decoding: either Huffman or arithmetic coding. */
michael@0:   if (cinfo->arith_code) {
michael@0: #ifdef D_ARITH_CODING_SUPPORTED
michael@0:     jinit_arith_decoder(cinfo);
michael@0: #else
michael@0:     ERREXIT(cinfo, JERR_ARITH_NOTIMPL);
michael@0: #endif
michael@0:   } else {
michael@0:     if (cinfo->progressive_mode) {
michael@0: #ifdef D_PROGRESSIVE_SUPPORTED
michael@0:       jinit_phuff_decoder(cinfo);
michael@0: #else
michael@0:       ERREXIT(cinfo, JERR_NOT_COMPILED);
michael@0: #endif
michael@0:     } else
michael@0:       jinit_huff_decoder(cinfo);
michael@0:   }
michael@0: 
michael@0:   /* Initialize principal buffer controllers. */
michael@0:   use_c_buffer = cinfo->inputctl->has_multiple_scans || cinfo->buffered_image;
michael@0:   jinit_d_coef_controller(cinfo, use_c_buffer);
michael@0: 
michael@0:   if (! cinfo->raw_data_out)
michael@0:     jinit_d_main_controller(cinfo, FALSE /* never need full buffer here */);
michael@0: 
michael@0:   /* We can now tell the memory manager to allocate virtual arrays. */
michael@0:   (*cinfo->mem->realize_virt_arrays) ((j_common_ptr) cinfo);
michael@0: 
michael@0:   /* Initialize input side of decompressor to consume first scan. */
michael@0:   (*cinfo->inputctl->start_input_pass) (cinfo);
michael@0: 
michael@0: #ifdef D_MULTISCAN_FILES_SUPPORTED
michael@0:   /* If jpeg_start_decompress will read the whole file, initialize
michael@0:    * progress monitoring appropriately.  The input step is counted
michael@0:    * as one pass.
michael@0:    */
michael@0:   if (cinfo->progress != NULL && ! cinfo->buffered_image &&
michael@0:       cinfo->inputctl->has_multiple_scans) {
michael@0:     int nscans;
michael@0:     /* Estimate number of scans to set pass_limit. */
michael@0:     if (cinfo->progressive_mode) {
michael@0:       /* Arbitrarily estimate 2 interleaved DC scans + 3 AC scans/component. */
michael@0:       nscans = 2 + 3 * cinfo->num_components;
michael@0:     } else {
michael@0:       /* For a nonprogressive multiscan file, estimate 1 scan per component. */
michael@0:       nscans = cinfo->num_components;
michael@0:     }
michael@0:     cinfo->progress->pass_counter = 0L;
michael@0:     cinfo->progress->pass_limit = (long) cinfo->total_iMCU_rows * nscans;
michael@0:     cinfo->progress->completed_passes = 0;
michael@0:     cinfo->progress->total_passes = (cinfo->enable_2pass_quant ? 3 : 2);
michael@0:     /* Count the input pass as done */
michael@0:     master->pass_number++;
michael@0:   }
michael@0: #endif /* D_MULTISCAN_FILES_SUPPORTED */
michael@0: }
michael@0: 
michael@0: 
michael@0: /*
michael@0:  * Per-pass setup.
michael@0:  * This is called at the beginning of each output pass.  We determine which
michael@0:  * modules will be active during this pass and give them appropriate
michael@0:  * start_pass calls.  We also set is_dummy_pass to indicate whether this
michael@0:  * is a "real" output pass or a dummy pass for color quantization.
michael@0:  * (In the latter case, jdapistd.c will crank the pass to completion.)
michael@0:  */
michael@0: 
michael@0: METHODDEF(void)
michael@0: prepare_for_output_pass (j_decompress_ptr cinfo)
michael@0: {
michael@0:   my_master_ptr master = (my_master_ptr) cinfo->master;
michael@0: 
michael@0:   if (master->pub.is_dummy_pass) {
michael@0: #ifdef QUANT_2PASS_SUPPORTED
michael@0:     /* Final pass of 2-pass quantization */
michael@0:     master->pub.is_dummy_pass = FALSE;
michael@0:     (*cinfo->cquantize->start_pass) (cinfo, FALSE);
michael@0:     (*cinfo->post->start_pass) (cinfo, JBUF_CRANK_DEST);
michael@0:     (*cinfo->main->start_pass) (cinfo, JBUF_CRANK_DEST);
michael@0: #else
michael@0:     ERREXIT(cinfo, JERR_NOT_COMPILED);
michael@0: #endif /* QUANT_2PASS_SUPPORTED */
michael@0:   } else {
michael@0:     if (cinfo->quantize_colors && cinfo->colormap == NULL) {
michael@0:       /* Select new quantization method */
michael@0:       if (cinfo->two_pass_quantize && cinfo->enable_2pass_quant) {
michael@0: 	cinfo->cquantize = master->quantizer_2pass;
michael@0: 	master->pub.is_dummy_pass = TRUE;
michael@0:       } else if (cinfo->enable_1pass_quant) {
michael@0: 	cinfo->cquantize = master->quantizer_1pass;
michael@0:       } else {
michael@0: 	ERREXIT(cinfo, JERR_MODE_CHANGE);
michael@0:       }
michael@0:     }
michael@0:     (*cinfo->idct->start_pass) (cinfo);
michael@0:     (*cinfo->coef->start_output_pass) (cinfo);
michael@0:     if (! cinfo->raw_data_out) {
michael@0:       if (! master->using_merged_upsample)
michael@0: 	(*cinfo->cconvert->start_pass) (cinfo);
michael@0:       (*cinfo->upsample->start_pass) (cinfo);
michael@0:       if (cinfo->quantize_colors)
michael@0: 	(*cinfo->cquantize->start_pass) (cinfo, master->pub.is_dummy_pass);
michael@0:       (*cinfo->post->start_pass) (cinfo,
michael@0: 	    (master->pub.is_dummy_pass ? JBUF_SAVE_AND_PASS : JBUF_PASS_THRU));
michael@0:       (*cinfo->main->start_pass) (cinfo, JBUF_PASS_THRU);
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   /* Set up progress monitor's pass info if present */
michael@0:   if (cinfo->progress != NULL) {
michael@0:     cinfo->progress->completed_passes = master->pass_number;
michael@0:     cinfo->progress->total_passes = master->pass_number +
michael@0: 				    (master->pub.is_dummy_pass ? 2 : 1);
michael@0:     /* In buffered-image mode, we assume one more output pass if EOI not
michael@0:      * yet reached, but no more passes if EOI has been reached.
michael@0:      */
michael@0:     if (cinfo->buffered_image && ! cinfo->inputctl->eoi_reached) {
michael@0:       cinfo->progress->total_passes += (cinfo->enable_2pass_quant ? 2 : 1);
michael@0:     }
michael@0:   }
michael@0: }
michael@0: 
michael@0: 
michael@0: /*
michael@0:  * Finish up at end of an output pass.
michael@0:  */
michael@0: 
michael@0: METHODDEF(void)
michael@0: finish_output_pass (j_decompress_ptr cinfo)
michael@0: {
michael@0:   my_master_ptr master = (my_master_ptr) cinfo->master;
michael@0: 
michael@0:   if (cinfo->quantize_colors)
michael@0:     (*cinfo->cquantize->finish_pass) (cinfo);
michael@0:   master->pass_number++;
michael@0: }
michael@0: 
michael@0: 
michael@0: #ifdef D_MULTISCAN_FILES_SUPPORTED
michael@0: 
michael@0: /*
michael@0:  * Switch to a new external colormap between output passes.
michael@0:  */
michael@0: 
michael@0: GLOBAL(void)
michael@0: jpeg_new_colormap (j_decompress_ptr cinfo)
michael@0: {
michael@0:   my_master_ptr master = (my_master_ptr) cinfo->master;
michael@0: 
michael@0:   /* Prevent application from calling me at wrong times */
michael@0:   if (cinfo->global_state != DSTATE_BUFIMAGE)
michael@0:     ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
michael@0: 
michael@0:   if (cinfo->quantize_colors && cinfo->enable_external_quant &&
michael@0:       cinfo->colormap != NULL) {
michael@0:     /* Select 2-pass quantizer for external colormap use */
michael@0:     cinfo->cquantize = master->quantizer_2pass;
michael@0:     /* Notify quantizer of colormap change */
michael@0:     (*cinfo->cquantize->new_color_map) (cinfo);
michael@0:     master->pub.is_dummy_pass = FALSE; /* just in case */
michael@0:   } else
michael@0:     ERREXIT(cinfo, JERR_MODE_CHANGE);
michael@0: }
michael@0: 
michael@0: #endif /* D_MULTISCAN_FILES_SUPPORTED */
michael@0: 
michael@0: 
michael@0: /*
michael@0:  * Initialize master decompression control and select active modules.
michael@0:  * This is performed at the start of jpeg_start_decompress.
michael@0:  */
michael@0: 
michael@0: GLOBAL(void)
michael@0: jinit_master_decompress (j_decompress_ptr cinfo)
michael@0: {
michael@0:   my_master_ptr master;
michael@0: 
michael@0:   master = (my_master_ptr)
michael@0:       (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
michael@0: 				  SIZEOF(my_decomp_master));
michael@0:   cinfo->master = (struct jpeg_decomp_master *) master;
michael@0:   master->pub.prepare_for_output_pass = prepare_for_output_pass;
michael@0:   master->pub.finish_output_pass = finish_output_pass;
michael@0: 
michael@0:   master->pub.is_dummy_pass = FALSE;
michael@0: 
michael@0:   master_selection(cinfo);
michael@0: }