vx32

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jcomapi.c (3110B)

      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 }