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      1 /*
      2  * jdinput.c
      3  *
      4  * This file was part of the Independent JPEG Group's software:
      5  * Copyright (C) 1991-1997, Thomas G. Lane.
      6  * libjpeg-turbo Modifications:
      7  * Copyright (C) 2010, 2016, D. R. Commander.
      8  * Copyright (C) 2015, Google, Inc.
      9  * For conditions of distribution and use, see the accompanying README.ijg
     10  * file.
     11  *
     12  * This file contains input control logic for the JPEG decompressor.
     13  * These routines are concerned with controlling the decompressor's input
     14  * processing (marker reading and coefficient decoding).  The actual input
     15  * reading is done in jdmarker.c, jdhuff.c, and jdphuff.c.
     16  */
     17 
     18 #define JPEG_INTERNALS
     19 #include "jinclude.h"
     20 #include "jpeglib.h"
     21 #include "jpegcomp.h"
     22 
     23 
     24 /* Private state */
     25 
     26 typedef struct {
     27   struct jpeg_input_controller pub; /* public fields */
     28 
     29   boolean inheaders;            /* TRUE until first SOS is reached */
     30 } my_input_controller;
     31 
     32 typedef my_input_controller * my_inputctl_ptr;
     33 
     34 
     35 /* Forward declarations */
     36 METHODDEF(int) consume_markers (j_decompress_ptr cinfo);
     37 
     38 
     39 /*
     40  * Routines to calculate various quantities related to the size of the image.
     41  */
     42 
     43 LOCAL(void)
     44 initial_setup (j_decompress_ptr cinfo)
     45 /* Called once, when first SOS marker is reached */
     46 {
     47   int ci;
     48   jpeg_component_info *compptr;
     49 
     50   /* Make sure image isn't bigger than I can handle */
     51   if ((long) cinfo->image_height > (long) JPEG_MAX_DIMENSION ||
     52       (long) cinfo->image_width > (long) JPEG_MAX_DIMENSION)
     53     ERREXIT1(cinfo, JERR_IMAGE_TOO_BIG, (unsigned int) JPEG_MAX_DIMENSION);
     54 
     55   /* For now, precision must match compiled-in value... */
     56   if (cinfo->data_precision != BITS_IN_JSAMPLE)
     57     ERREXIT1(cinfo, JERR_BAD_PRECISION, cinfo->data_precision);
     58 
     59   /* Check that number of components won't exceed internal array sizes */
     60   if (cinfo->num_components > MAX_COMPONENTS)
     61     ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components,
     62              MAX_COMPONENTS);
     63 
     64   /* Compute maximum sampling factors; check factor validity */
     65   cinfo->max_h_samp_factor = 1;
     66   cinfo->max_v_samp_factor = 1;
     67   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
     68        ci++, compptr++) {
     69     if (compptr->h_samp_factor<=0 || compptr->h_samp_factor>MAX_SAMP_FACTOR ||
     70         compptr->v_samp_factor<=0 || compptr->v_samp_factor>MAX_SAMP_FACTOR)
     71       ERREXIT(cinfo, JERR_BAD_SAMPLING);
     72     cinfo->max_h_samp_factor = MAX(cinfo->max_h_samp_factor,
     73                                    compptr->h_samp_factor);
     74     cinfo->max_v_samp_factor = MAX(cinfo->max_v_samp_factor,
     75                                    compptr->v_samp_factor);
     76   }
     77 
     78 #if JPEG_LIB_VERSION >=80
     79     cinfo->block_size = DCTSIZE;
     80     cinfo->natural_order = jpeg_natural_order;
     81     cinfo->lim_Se = DCTSIZE2-1;
     82 #endif
     83 
     84   /* We initialize DCT_scaled_size and min_DCT_scaled_size to DCTSIZE.
     85    * In the full decompressor, this will be overridden by jdmaster.c;
     86    * but in the transcoder, jdmaster.c is not used, so we must do it here.
     87    */
     88 #if JPEG_LIB_VERSION >= 70
     89   cinfo->min_DCT_h_scaled_size = cinfo->min_DCT_v_scaled_size = DCTSIZE;
     90 #else
     91   cinfo->min_DCT_scaled_size = DCTSIZE;
     92 #endif
     93 
     94   /* Compute dimensions of components */
     95   for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
     96        ci++, compptr++) {
     97 #if JPEG_LIB_VERSION >= 70
     98     compptr->DCT_h_scaled_size = compptr->DCT_v_scaled_size = DCTSIZE;
     99 #else
    100     compptr->DCT_scaled_size = DCTSIZE;
    101 #endif
    102     /* Size in DCT blocks */
    103     compptr->width_in_blocks = (JDIMENSION)
    104       jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor,
    105                     (long) (cinfo->max_h_samp_factor * DCTSIZE));
    106     compptr->height_in_blocks = (JDIMENSION)
    107       jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor,
    108                     (long) (cinfo->max_v_samp_factor * DCTSIZE));
    109     /* Set the first and last MCU columns to decompress from multi-scan images.
    110      * By default, decompress all of the MCU columns.
    111      */
    112     cinfo->master->first_MCU_col[ci] = 0;
    113     cinfo->master->last_MCU_col[ci] = compptr->width_in_blocks - 1;
    114     /* downsampled_width and downsampled_height will also be overridden by
    115      * jdmaster.c if we are doing full decompression.  The transcoder library
    116      * doesn't use these values, but the calling application might.
    117      */
    118     /* Size in samples */
    119     compptr->downsampled_width = (JDIMENSION)
    120       jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor,
    121                     (long) cinfo->max_h_samp_factor);
    122     compptr->downsampled_height = (JDIMENSION)
    123       jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor,
    124                     (long) cinfo->max_v_samp_factor);
    125     /* Mark component needed, until color conversion says otherwise */
    126     compptr->component_needed = TRUE;
    127     /* Mark no quantization table yet saved for component */
    128     compptr->quant_table = NULL;
    129   }
    130 
    131   /* Compute number of fully interleaved MCU rows. */
    132   cinfo->total_iMCU_rows = (JDIMENSION)
    133     jdiv_round_up((long) cinfo->image_height,
    134                   (long) (cinfo->max_v_samp_factor*DCTSIZE));
    135 
    136   /* Decide whether file contains multiple scans */
    137   if (cinfo->comps_in_scan < cinfo->num_components || cinfo->progressive_mode)
    138     cinfo->inputctl->has_multiple_scans = TRUE;
    139   else
    140     cinfo->inputctl->has_multiple_scans = FALSE;
    141 }
    142 
    143 
    144 LOCAL(void)
    145 per_scan_setup (j_decompress_ptr cinfo)
    146 /* Do computations that are needed before processing a JPEG scan */
    147 /* cinfo->comps_in_scan and cinfo->cur_comp_info[] were set from SOS marker */
    148 {
    149   int ci, mcublks, tmp;
    150   jpeg_component_info *compptr;
    151 
    152   if (cinfo->comps_in_scan == 1) {
    153 
    154     /* Noninterleaved (single-component) scan */
    155     compptr = cinfo->cur_comp_info[0];
    156 
    157     /* Overall image size in MCUs */
    158     cinfo->MCUs_per_row = compptr->width_in_blocks;
    159     cinfo->MCU_rows_in_scan = compptr->height_in_blocks;
    160 
    161     /* For noninterleaved scan, always one block per MCU */
    162     compptr->MCU_width = 1;
    163     compptr->MCU_height = 1;
    164     compptr->MCU_blocks = 1;
    165     compptr->MCU_sample_width = compptr->_DCT_scaled_size;
    166     compptr->last_col_width = 1;
    167     /* For noninterleaved scans, it is convenient to define last_row_height
    168      * as the number of block rows present in the last iMCU row.
    169      */
    170     tmp = (int) (compptr->height_in_blocks % compptr->v_samp_factor);
    171     if (tmp == 0) tmp = compptr->v_samp_factor;
    172     compptr->last_row_height = tmp;
    173 
    174     /* Prepare array describing MCU composition */
    175     cinfo->blocks_in_MCU = 1;
    176     cinfo->MCU_membership[0] = 0;
    177 
    178   } else {
    179 
    180     /* Interleaved (multi-component) scan */
    181     if (cinfo->comps_in_scan <= 0 || cinfo->comps_in_scan > MAX_COMPS_IN_SCAN)
    182       ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->comps_in_scan,
    183                MAX_COMPS_IN_SCAN);
    184 
    185     /* Overall image size in MCUs */
    186     cinfo->MCUs_per_row = (JDIMENSION)
    187       jdiv_round_up((long) cinfo->image_width,
    188                     (long) (cinfo->max_h_samp_factor*DCTSIZE));
    189     cinfo->MCU_rows_in_scan = (JDIMENSION)
    190       jdiv_round_up((long) cinfo->image_height,
    191                     (long) (cinfo->max_v_samp_factor*DCTSIZE));
    192 
    193     cinfo->blocks_in_MCU = 0;
    194 
    195     for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
    196       compptr = cinfo->cur_comp_info[ci];
    197       /* Sampling factors give # of blocks of component in each MCU */
    198       compptr->MCU_width = compptr->h_samp_factor;
    199       compptr->MCU_height = compptr->v_samp_factor;
    200       compptr->MCU_blocks = compptr->MCU_width * compptr->MCU_height;
    201       compptr->MCU_sample_width = compptr->MCU_width * compptr->_DCT_scaled_size;
    202       /* Figure number of non-dummy blocks in last MCU column & row */
    203       tmp = (int) (compptr->width_in_blocks % compptr->MCU_width);
    204       if (tmp == 0) tmp = compptr->MCU_width;
    205       compptr->last_col_width = tmp;
    206       tmp = (int) (compptr->height_in_blocks % compptr->MCU_height);
    207       if (tmp == 0) tmp = compptr->MCU_height;
    208       compptr->last_row_height = tmp;
    209       /* Prepare array describing MCU composition */
    210       mcublks = compptr->MCU_blocks;
    211       if (cinfo->blocks_in_MCU + mcublks > D_MAX_BLOCKS_IN_MCU)
    212         ERREXIT(cinfo, JERR_BAD_MCU_SIZE);
    213       while (mcublks-- > 0) {
    214         cinfo->MCU_membership[cinfo->blocks_in_MCU++] = ci;
    215       }
    216     }
    217 
    218   }
    219 }
    220 
    221 
    222 /*
    223  * Save away a copy of the Q-table referenced by each component present
    224  * in the current scan, unless already saved during a prior scan.
    225  *
    226  * In a multiple-scan JPEG file, the encoder could assign different components
    227  * the same Q-table slot number, but change table definitions between scans
    228  * so that each component uses a different Q-table.  (The IJG encoder is not
    229  * currently capable of doing this, but other encoders might.)  Since we want
    230  * to be able to dequantize all the components at the end of the file, this
    231  * means that we have to save away the table actually used for each component.
    232  * We do this by copying the table at the start of the first scan containing
    233  * the component.
    234  * The JPEG spec prohibits the encoder from changing the contents of a Q-table
    235  * slot between scans of a component using that slot.  If the encoder does so
    236  * anyway, this decoder will simply use the Q-table values that were current
    237  * at the start of the first scan for the component.
    238  *
    239  * The decompressor output side looks only at the saved quant tables,
    240  * not at the current Q-table slots.
    241  */
    242 
    243 LOCAL(void)
    244 latch_quant_tables (j_decompress_ptr cinfo)
    245 {
    246   int ci, qtblno;
    247   jpeg_component_info *compptr;
    248   JQUANT_TBL * qtbl;
    249 
    250   for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
    251     compptr = cinfo->cur_comp_info[ci];
    252     /* No work if we already saved Q-table for this component */
    253     if (compptr->quant_table != NULL)
    254       continue;
    255     /* Make sure specified quantization table is present */
    256     qtblno = compptr->quant_tbl_no;
    257     if (qtblno < 0 || qtblno >= NUM_QUANT_TBLS ||
    258         cinfo->quant_tbl_ptrs[qtblno] == NULL)
    259       ERREXIT1(cinfo, JERR_NO_QUANT_TABLE, qtblno);
    260     /* OK, save away the quantization table */
    261     qtbl = (JQUANT_TBL *)
    262       (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
    263                                   sizeof(JQUANT_TBL));
    264     MEMCOPY(qtbl, cinfo->quant_tbl_ptrs[qtblno], sizeof(JQUANT_TBL));
    265     compptr->quant_table = qtbl;
    266   }
    267 }
    268 
    269 
    270 /*
    271  * Initialize the input modules to read a scan of compressed data.
    272  * The first call to this is done by jdmaster.c after initializing
    273  * the entire decompressor (during jpeg_start_decompress).
    274  * Subsequent calls come from consume_markers, below.
    275  */
    276 
    277 METHODDEF(void)
    278 start_input_pass (j_decompress_ptr cinfo)
    279 {
    280   per_scan_setup(cinfo);
    281   latch_quant_tables(cinfo);
    282   (*cinfo->entropy->start_pass) (cinfo);
    283   (*cinfo->coef->start_input_pass) (cinfo);
    284   cinfo->inputctl->consume_input = cinfo->coef->consume_data;
    285 }
    286 
    287 
    288 /*
    289  * Finish up after inputting a compressed-data scan.
    290  * This is called by the coefficient controller after it's read all
    291  * the expected data of the scan.
    292  */
    293 
    294 METHODDEF(void)
    295 finish_input_pass (j_decompress_ptr cinfo)
    296 {
    297   cinfo->inputctl->consume_input = consume_markers;
    298 }
    299 
    300 
    301 /*
    302  * Read JPEG markers before, between, or after compressed-data scans.
    303  * Change state as necessary when a new scan is reached.
    304  * Return value is JPEG_SUSPENDED, JPEG_REACHED_SOS, or JPEG_REACHED_EOI.
    305  *
    306  * The consume_input method pointer points either here or to the
    307  * coefficient controller's consume_data routine, depending on whether
    308  * we are reading a compressed data segment or inter-segment markers.
    309  */
    310 
    311 METHODDEF(int)
    312 consume_markers (j_decompress_ptr cinfo)
    313 {
    314   my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl;
    315   int val;
    316 
    317   if (inputctl->pub.eoi_reached) /* After hitting EOI, read no further */
    318     return JPEG_REACHED_EOI;
    319 
    320   val = (*cinfo->marker->read_markers) (cinfo);
    321 
    322   switch (val) {
    323   case JPEG_REACHED_SOS:        /* Found SOS */
    324     if (inputctl->inheaders) {  /* 1st SOS */
    325       initial_setup(cinfo);
    326       inputctl->inheaders = FALSE;
    327       /* Note: start_input_pass must be called by jdmaster.c
    328        * before any more input can be consumed.  jdapimin.c is
    329        * responsible for enforcing this sequencing.
    330        */
    331     } else {                    /* 2nd or later SOS marker */
    332       if (! inputctl->pub.has_multiple_scans)
    333         ERREXIT(cinfo, JERR_EOI_EXPECTED); /* Oops, I wasn't expecting this! */
    334       start_input_pass(cinfo);
    335     }
    336     break;
    337   case JPEG_REACHED_EOI:        /* Found EOI */
    338     inputctl->pub.eoi_reached = TRUE;
    339     if (inputctl->inheaders) {  /* Tables-only datastream, apparently */
    340       if (cinfo->marker->saw_SOF)
    341         ERREXIT(cinfo, JERR_SOF_NO_SOS);
    342     } else {
    343       /* Prevent infinite loop in coef ctlr's decompress_data routine
    344        * if user set output_scan_number larger than number of scans.
    345        */
    346       if (cinfo->output_scan_number > cinfo->input_scan_number)
    347         cinfo->output_scan_number = cinfo->input_scan_number;
    348     }
    349     break;
    350   case JPEG_SUSPENDED:
    351     break;
    352   }
    353 
    354   return val;
    355 }
    356 
    357 
    358 /*
    359  * Reset state to begin a fresh datastream.
    360  */
    361 
    362 METHODDEF(void)
    363 reset_input_controller (j_decompress_ptr cinfo)
    364 {
    365   my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl;
    366 
    367   inputctl->pub.consume_input = consume_markers;
    368   inputctl->pub.has_multiple_scans = FALSE; /* "unknown" would be better */
    369   inputctl->pub.eoi_reached = FALSE;
    370   inputctl->inheaders = TRUE;
    371   /* Reset other modules */
    372   (*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo);
    373   (*cinfo->marker->reset_marker_reader) (cinfo);
    374   /* Reset progression state -- would be cleaner if entropy decoder did this */
    375   cinfo->coef_bits = NULL;
    376 }
    377 
    378 
    379 /*
    380  * Initialize the input controller module.
    381  * This is called only once, when the decompression object is created.
    382  */
    383 
    384 GLOBAL(void)
    385 jinit_input_controller (j_decompress_ptr cinfo)
    386 {
    387   my_inputctl_ptr inputctl;
    388 
    389   /* Create subobject in permanent pool */
    390   inputctl = (my_inputctl_ptr)
    391     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
    392                                 sizeof(my_input_controller));
    393   cinfo->inputctl = (struct jpeg_input_controller *) inputctl;
    394   /* Initialize method pointers */
    395   inputctl->pub.consume_input = consume_markers;
    396   inputctl->pub.reset_input_controller = reset_input_controller;
    397   inputctl->pub.start_input_pass = start_input_pass;
    398   inputctl->pub.finish_input_pass = finish_input_pass;
    399   /* Initialize state: can't use reset_input_controller since we don't
    400    * want to try to reset other modules yet.
    401    */
    402   inputctl->pub.has_multiple_scans = FALSE; /* "unknown" would be better */
    403   inputctl->pub.eoi_reached = FALSE;
    404   inputctl->inheaders = TRUE;
    405 }
    406