src/jpeg/jcomapi.c

   1 /*
   2  * jcomapi.c
   3  *
   4  * Copyright (C) 1994-1997, 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 application interface routines that are used for both
   9  * compression and decompression.
  10  */
  11
  12 #define JPEG_INTERNALS
  13 #include "jinclude.h"
  14 #include "jpeglib.h"
  15
  16
  17 /*
  18  * Abort processing of a JPEG compression or decompression operation,
  19  * but don't destroy the object itself.
  20  *
  21  * For this, we merely clean up all the nonpermanent memory pools.
  22  * Note that temp files (virtual arrays) are not allowed to belong to
  23  * the permanent pool, so we will be able to close all temp files here.
  24  * Closing a data source or destination, if necessary, is the application's
  25  * responsibility.
  26  */
  27
  28 GLOBAL(void)
  29 jpeg_abort (j_common_ptr cinfo)
  30 {
  31   int pool;
  32
  33   /* Do nothing if called on a not-initialized or destroyed JPEG object. */
  34   if (cinfo->mem == NULL)
  35     return;
  36
  37   /* Releasing pools in reverse order might help avoid fragmentation
  38    * with some (brain-damaged) malloc libraries.
  39    */
  40   for (pool = JPOOL_NUMPOOLS-1; pool > JPOOL_PERMANENT; pool--) {
  41     (*cinfo->mem->free_pool) (cinfo, pool);
  42   }
  43
  44   /* Reset overall state for possible reuse of object */
  45   if (cinfo->is_decompressor) {
  46     cinfo->global_state = DSTATE_START;
  47     /* Try to keep application from accessing now-deleted marker list.
  48      * A bit kludgy to do it here, but this is the most central place.
  49      */
  50     ((j_decompress_ptr) cinfo)->marker_list = NULL;
  51   } else {
  52     cinfo->global_state = CSTATE_START;
  53   }
  54 }
  55
  56
  57 /*
  58  * Destruction of a JPEG object.
  59  *
  60  * Everything gets deallocated except the master jpeg_compress_struct itself
  61  * and the error manager struct.  Both of these are supplied by the application
  62  * and must be freed, if necessary, by the application.  (Often they are on
  63  * the stack and so don't need to be freed anyway.)
  64  * Closing a data source or destination, if necessary, is the application's
  65  * responsibility.
  66  */
  67
  68 GLOBAL(void)
  69 jpeg_destroy (j_common_ptr cinfo)
  70 {
  71   /* We need only tell the memory manager to release everything. */
  72   /* NB: mem pointer is NULL if memory mgr failed to initialize. */
  73   if (cinfo->mem != NULL)
  74     (*cinfo->mem->self_destruct) (cinfo);
  75   cinfo->mem = NULL;            /* be safe if jpeg_destroy is called twice */
  76   cinfo->global_state = 0;      /* mark it destroyed */
  77 }
  78
  79
  80 /*
  81  * Convenience routines for allocating quantization and Huffman tables.
  82  * (Would jutils.c be a more reasonable place to put these?)
  83  */
  84
  85 GLOBAL(JQUANT_TBL *)
  86 jpeg_alloc_quant_table (j_common_ptr cinfo)
  87 {
  88   JQUANT_TBL *tbl;
  89
  90   tbl = (JQUANT_TBL *)
  91     (*cinfo->mem->alloc_small) (cinfo, JPOOL_PERMANENT, SIZEOF(JQUANT_TBL));
  92   tbl->sent_table = FALSE;      /* make sure this is false in any new table */
  93   return tbl;
  94 }
  95
  96
  97 GLOBAL(JHUFF_TBL *)
  98 jpeg_alloc_huff_table (j_common_ptr cinfo)
  99 {
 100   JHUFF_TBL *tbl;
 101
 102   tbl = (JHUFF_TBL *)
 103     (*cinfo->mem->alloc_small) (cinfo, JPOOL_PERMANENT, SIZEOF(JHUFF_TBL));
 104   tbl->sent_table = FALSE;      /* make sure this is false in any new table */
 105   return tbl;
 106 }