Quake-III-Arena

Quake III Arena GPL Source Release
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jdtrans.cpp (4133B)

      1 /*
      2  * jdtrans.c
      3  *
      4  * Copyright (C) 1995, 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  * Returns NULL if suspended.  This case need be checked only if
     34  * a suspending data source is used.
     35  */
     36 
     37 GLOBAL jvirt_barray_ptr *
     38 jpeg_read_coefficients (j_decompress_ptr cinfo)
     39 {
     40   if (cinfo->global_state == DSTATE_READY) {
     41     /* First call: initialize active modules */
     42     transdecode_master_selection(cinfo);
     43     cinfo->global_state = DSTATE_RDCOEFS;
     44   } else if (cinfo->global_state != DSTATE_RDCOEFS)
     45     ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
     46   /* Absorb whole file into the coef buffer */
     47   for (;;) {
     48     int retcode;
     49     /* Call progress monitor hook if present */
     50     if (cinfo->progress != NULL)
     51       (*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
     52     /* Absorb some more input */
     53     retcode = (*cinfo->inputctl->consume_input) (cinfo);
     54     if (retcode == JPEG_SUSPENDED)
     55       return NULL;
     56     if (retcode == JPEG_REACHED_EOI)
     57       break;
     58     /* Advance progress counter if appropriate */
     59     if (cinfo->progress != NULL &&
     60 	(retcode == JPEG_ROW_COMPLETED || retcode == JPEG_REACHED_SOS)) {
     61       if (++cinfo->progress->pass_counter >= cinfo->progress->pass_limit) {
     62 	/* startup underestimated number of scans; ratchet up one scan */
     63 	cinfo->progress->pass_limit += (long) cinfo->total_iMCU_rows;
     64       }
     65     }
     66   }
     67   /* Set state so that jpeg_finish_decompress does the right thing */
     68   cinfo->global_state = DSTATE_STOPPING;
     69   return cinfo->coef->coef_arrays;
     70 }
     71 
     72 
     73 /*
     74  * Master selection of decompression modules for transcoding.
     75  * This substitutes for jdmaster.c's initialization of the full decompressor.
     76  */
     77 
     78 LOCAL void
     79 transdecode_master_selection (j_decompress_ptr cinfo)
     80 {
     81   /* Entropy decoding: either Huffman or arithmetic coding. */
     82   if (cinfo->arith_code) {
     83     ERREXIT(cinfo, JERR_ARITH_NOTIMPL);
     84   } else {
     85     if (cinfo->progressive_mode) {
     86 #ifdef D_PROGRESSIVE_SUPPORTED
     87       jinit_phuff_decoder(cinfo);
     88 #else
     89       ERREXIT(cinfo, JERR_NOT_COMPILED);
     90 #endif
     91     } else
     92       jinit_huff_decoder(cinfo);
     93   }
     94 
     95   /* Always get a full-image coefficient buffer. */
     96   jinit_d_coef_controller(cinfo, TRUE);
     97 
     98   /* We can now tell the memory manager to allocate virtual arrays. */
     99   (*cinfo->mem->realize_virt_arrays) ((j_common_ptr) cinfo);
    100 
    101   /* Initialize input side of decompressor to consume first scan. */
    102   (*cinfo->inputctl->start_input_pass) (cinfo);
    103 
    104   /* Initialize progress monitoring. */
    105   if (cinfo->progress != NULL) {
    106     int nscans;
    107     /* Estimate number of scans to set pass_limit. */
    108     if (cinfo->progressive_mode) {
    109       /* Arbitrarily estimate 2 interleaved DC scans + 3 AC scans/component. */
    110       nscans = 2 + 3 * cinfo->num_components;
    111     } else if (cinfo->inputctl->has_multiple_scans) {
    112       /* For a nonprogressive multiscan file, estimate 1 scan per component. */
    113       nscans = cinfo->num_components;
    114     } else {
    115       nscans = 1;
    116     }
    117     cinfo->progress->pass_counter = 0L;
    118     cinfo->progress->pass_limit = (long) cinfo->total_iMCU_rows * nscans;
    119     cinfo->progress->completed_passes = 0;
    120     cinfo->progress->total_passes = 1;
    121   }
    122 }