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 }