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      1 /*
      2  * jdtrans.c
      3  *
      4  * Copyright (C) 1995-1997, Thomas G. Lane.
      5  * This file is part of the Independent JPEG Group's software.
      6  * For conditions of distribution and use, see the accompanying README file.
      7  *
      8  * This file contains library routines for transcoding decompression,
      9  * that is, reading raw DCT coefficient arrays from an input JPEG file.
     10  * The routines in jdapimin.c will also be needed by a transcoder.
     11  */
     12 
     13 #define JPEG_INTERNALS
     14 #include "jinclude.h"
     15 #include "jpeglib.h"
     16 
     17 
     18 /* Forward declarations */
     19 LOCAL(void) transdecode_master_selection JPP((j_decompress_ptr cinfo));
     20 
     21 
     22 /*
     23  * Read the coefficient arrays from a JPEG file.
     24  * jpeg_read_header must be completed before calling this.
     25  *
     26  * The entire image is read into a set of virtual coefficient-block arrays,
     27  * one per component.  The return value is a pointer to the array of
     28  * virtual-array descriptors.  These can be manipulated directly via the
     29  * JPEG memory manager, or handed off to jpeg_write_coefficients().
     30  * To release the memory occupied by the virtual arrays, call
     31  * jpeg_finish_decompress() when done with the data.
     32  *
     33  * An alternative usage is to simply obtain access to the coefficient arrays
     34  * during a buffered-image-mode decompression operation.  This is allowed
     35  * after any jpeg_finish_output() call.  The arrays can be accessed until
     36  * jpeg_finish_decompress() is called.  (Note that any call to the library
     37  * may reposition the arrays, so don't rely on access_virt_barray() results
     38  * to stay valid across library calls.)
     39  *
     40  * Returns NULL if suspended.  This case need be checked only if
     41  * a suspending data source is used.
     42  */
     43 
     44 GLOBAL(jvirt_barray_ptr *)
     45 jpeg_read_coefficients (j_decompress_ptr cinfo)
     46 {
     47   if (cinfo->global_state == DSTATE_READY) {
     48     /* First call: initialize active modules */
     49     transdecode_master_selection(cinfo);
     50     cinfo->global_state = DSTATE_RDCOEFS;
     51   }
     52   if (cinfo->global_state == DSTATE_RDCOEFS) {
     53     /* Absorb whole file into the coef buffer */
     54     for (;;) {
     55       int retcode;
     56       /* Call progress monitor hook if present */
     57       if (cinfo->progress != NULL)
     58         (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
     59       /* Absorb some more input */
     60       retcode = (*cinfo->inputctl->consume_input) (cinfo);
     61       if (retcode == JPEG_SUSPENDED)
     62         return NULL;
     63       if (retcode == JPEG_REACHED_EOI)
     64         break;
     65       /* Advance progress counter if appropriate */
     66       if (cinfo->progress != NULL &&
     67 	  (retcode == JPEG_ROW_COMPLETED || retcode == JPEG_REACHED_SOS)) {
     68         if (++cinfo->progress->pass_counter >= cinfo->progress->pass_limit) {
     69 	  /* startup underestimated number of scans; ratchet up one scan */
     70         cinfo->progress->pass_limit += (long) cinfo->total_iMCU_rows;
     71         }
     72       }
     73     }
     74     /* Set state so that jpeg_finish_decompress does the right thing */
     75     cinfo->global_state = DSTATE_STOPPING;
     76   }
     77   /* At this point we should be in state DSTATE_STOPPING if being used
     78    * standalone, or in state DSTATE_BUFIMAGE if being invoked to get access
     79    * to the coefficients during a full buffered-image-mode decompression.
     80    */
     81   if ((cinfo->global_state == DSTATE_STOPPING ||
     82        cinfo->global_state == DSTATE_BUFIMAGE) && cinfo->buffered_image) {
     83     return cinfo->coef->coef_arrays;
     84   }
     85   /* Oops, improper usage */
     86   ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
     87   return NULL;			/* keep compiler happy */
     88 }
     89 
     90 LOCAL(boolean)
     91 jpeg_build_huffman_index_progressive(j_decompress_ptr cinfo,
     92         huffman_index *index)
     93 {
     94   if (cinfo->global_state == DSTATE_READY) {
     95     printf("Progressive Mode\n");
     96     /* First call: initialize active modules */
     97     transdecode_master_selection(cinfo);
     98     cinfo->global_state = DSTATE_RDCOEFS;
     99   }
    100   if (cinfo->global_state == DSTATE_RDCOEFS) {
    101     int mcu, i;
    102     cinfo->marker->get_sos_marker_position(cinfo, index);
    103 
    104     /* Absorb whole file into the coef buffer */
    105     for (mcu = 0; mcu < cinfo->total_iMCU_rows; mcu++) {
    106       int retcode = 0;
    107       /* Call progress monitor hook if present */
    108       if (cinfo->progress != NULL)
    109         (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
    110       /* Absorb some more input */
    111       jinit_phuff_decoder(cinfo);
    112       for (i = 0; i < index->scan_count; i++) {
    113         (*cinfo->inputctl->finish_input_pass) (cinfo);
    114         jset_input_stream_position(cinfo, index->scan[i].bitstream_offset);
    115         cinfo->unread_marker = 0;
    116         retcode = (*cinfo->inputctl->consume_input_build_huffman_index)
    117                     (cinfo, index, i);
    118         if (retcode == JPEG_REACHED_EOI)
    119           break;
    120         cinfo->input_iMCU_row = mcu;
    121         if (mcu != 0)
    122           (*cinfo->entropy->configure_huffman_decoder)
    123                 (cinfo, index->scan[i].prev_MCU_offset);
    124         cinfo->input_scan_number = i;
    125         retcode = (*cinfo->inputctl->consume_input_build_huffman_index)
    126                     (cinfo, index, i);
    127       }
    128       if (retcode == JPEG_SUSPENDED)
    129         return FALSE;
    130       if (retcode == JPEG_REACHED_EOI)
    131         break;
    132       /* Advance progress counter if appropriate */
    133       if (cinfo->progress != NULL &&
    134 	  (retcode == JPEG_ROW_COMPLETED || retcode == JPEG_REACHED_SOS)) {
    135         if (++cinfo->progress->pass_counter >= cinfo->progress->pass_limit) {
    136 	  /* startup underestimated number of scans; ratchet up one scan */
    137           cinfo->progress->pass_limit += (long) cinfo->total_iMCU_rows;
    138         }
    139       }
    140     }
    141     cinfo->global_state = DSTATE_STOPPING;
    142   }
    143   /* At this point we should be in state DSTATE_STOPPING if being used
    144    * standalone, or in state DSTATE_BUFIMAGE if being invoked to get access
    145    * to the coefficients during a full buffered-image-mode decompression.
    146    */
    147   if ((cinfo->global_state == DSTATE_STOPPING ||
    148        cinfo->global_state == DSTATE_BUFIMAGE) && cinfo->buffered_image) {
    149     return TRUE;
    150   }
    151   /* Oops, improper usage */
    152   ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
    153   return FALSE;			/* keep compiler happy */
    154 }
    155 
    156 LOCAL(boolean)
    157 jpeg_build_huffman_index_baseline(j_decompress_ptr cinfo, huffman_index *index)
    158 {
    159   if (cinfo->global_state == DSTATE_READY) {
    160     printf("Baseline Mode\n");
    161     /* First call: initialize active modules */
    162     transdecode_master_selection(cinfo);
    163     cinfo->global_state = DSTATE_RDCOEFS;
    164   }
    165   if (cinfo->global_state == DSTATE_RDCOEFS) {
    166     /* Absorb whole file into the coef buffer */
    167     for (;;) {
    168       int retcode;
    169       /* Call progress monitor hook if present */
    170       if (cinfo->progress != NULL)
    171         (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
    172       /* Absorb some more input */
    173       retcode = (*cinfo->inputctl->consume_input_build_huffman_index)
    174                     (cinfo, index, 0);
    175       if (retcode == JPEG_SUSPENDED)
    176         return FALSE;
    177       if (retcode == JPEG_REACHED_EOI)
    178         break;
    179       if (retcode == JPEG_SCAN_COMPLETED)
    180         break;
    181 
    182       /* Advance progress counter if appropriate */
    183       if (cinfo->progress != NULL &&
    184 	  (retcode == JPEG_ROW_COMPLETED || retcode == JPEG_REACHED_SOS)) {
    185         if (++cinfo->progress->pass_counter >= cinfo->progress->pass_limit) {
    186 	  /* startup underestimated number of scans; ratchet up one scan */
    187         cinfo->progress->pass_limit += (long) cinfo->total_iMCU_rows;
    188         }
    189       }
    190     }
    191     /* Set state so that jpeg_finish_decompress does the right thing */
    192     cinfo->global_state = DSTATE_STOPPING;
    193   }
    194   /* At this point we should be in state DSTATE_STOPPING if being used
    195    * standalone, or in state DSTATE_BUFIMAGE if being invoked to get access
    196    * to the coefficients during a full buffered-image-mode decompression.
    197    */
    198   if ((cinfo->global_state == DSTATE_STOPPING ||
    199        cinfo->global_state == DSTATE_BUFIMAGE) && cinfo->buffered_image) {
    200     return TRUE;
    201   }
    202   /* Oops, improper usage */
    203   ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
    204   return FALSE;			/* keep compiler happy */
    205 }
    206 
    207 GLOBAL(boolean)
    208 jpeg_build_huffman_index(j_decompress_ptr cinfo, huffman_index *index)
    209 {
    210     cinfo->tile_decode = TRUE;
    211     if (cinfo->progressive_mode)
    212       return jpeg_build_huffman_index_progressive(cinfo, index);
    213     else
    214       return jpeg_build_huffman_index_baseline(cinfo, index);
    215 }
    216 
    217 /*
    218  * Master selection of decompression modules for transcoding.
    219  * This substitutes for jdmaster.c's initialization of the full decompressor.
    220  */
    221 
    222 LOCAL(void)
    223 transdecode_master_selection (j_decompress_ptr cinfo)
    224 {
    225   /* This is effectively a buffered-image operation. */
    226   cinfo->buffered_image = TRUE;
    227 
    228   /* Entropy decoding: either Huffman or arithmetic coding. */
    229   if (cinfo->arith_code) {
    230     ERREXIT(cinfo, JERR_ARITH_NOTIMPL);
    231   } else {
    232     if (cinfo->progressive_mode) {
    233 #ifdef D_PROGRESSIVE_SUPPORTED
    234       jinit_phuff_decoder(cinfo);
    235 #else
    236       ERREXIT(cinfo, JERR_NOT_COMPILED);
    237 #endif
    238     } else {
    239       jinit_huff_decoder(cinfo);
    240     }
    241   }
    242 
    243   /* Always get a full-image coefficient buffer. */
    244   jinit_d_coef_controller(cinfo, TRUE);
    245 
    246   /* We can now tell the memory manager to allocate virtual arrays. */
    247   (*cinfo->mem->realize_virt_arrays) ((j_common_ptr) cinfo);
    248 
    249   /* Initialize input side of decompressor to consume first scan. */
    250   (*cinfo->inputctl->start_input_pass) (cinfo);
    251 
    252   /* Initialize progress monitoring. */
    253   if (cinfo->progress != NULL) {
    254     int nscans;
    255     /* Estimate number of scans to set pass_limit. */
    256     if (cinfo->progressive_mode) {
    257       /* Arbitrarily estimate 2 interleaved DC scans + 3 AC scans/component. */
    258       nscans = 2 + 3 * cinfo->num_components;
    259     } else if (cinfo->inputctl->has_multiple_scans) {
    260       /* For a nonprogressive multiscan file, estimate 1 scan per component. */
    261       nscans = cinfo->num_components;
    262     } else {
    263       nscans = 1;
    264     }
    265     cinfo->progress->pass_counter = 0L;
    266     cinfo->progress->pass_limit = (long) cinfo->total_iMCU_rows * nscans;
    267     cinfo->progress->completed_passes = 0;
    268     cinfo->progress->total_passes = 1;
    269   }
    270 }
    271