    /*
     * jcomapi.c
     *
     * Copyright (C) 1994-1997, Thomas G. Lane.
     * This file is part of the Independent JPEG Group's software.
     * For conditions of distribution and use, see the accompanying README file.
     *
     * This file contains application interface routines that are used for both
     * compression and decompression.
     */

    #define JPEG_INTERNALS
    #include "jinclude.h"
    #include "jpeglib.h"

    /*
     * Abort processing of a JPEG compression or decompression operation,
     * but don't destroy the object itself.
     *
     * For this, we merely clean up all the nonpermanent memory pools.
     * Note that temp files (virtual arrays) are not allowed to belong to
     * the permanent pool, so we will be able to close all temp files here.
     * Closing a data source or destination, if necessary, is the application's
     * responsibility.
     */

    GLOBAL(void)
    jpeg_abort (j_common_ptr cinfo)
    {
      int pool;

      /* Do nothing if called on a not-initialized or destroyed JPEG object. */
      if (cinfo->mem == NULL)
        return;

      /* Releasing pools in reverse order might help avoid fragmentation
       * with some (brain-damaged) malloc libraries.
       */
      for (pool = JPOOL_NUMPOOLS-1; pool > JPOOL_PERMANENT; pool--) {
        (*cinfo->mem->free_pool) (cinfo, pool);
      }

      /* Reset overall state for possible reuse of object */
      if (cinfo->is_decompressor) {
        cinfo->global_state = DSTATE_START;
        /* Try to keep application from accessing now-deleted marker list.
         * A bit kludgy to do it here, but this is the most central place.
         */
        ((j_decompress_ptr) cinfo)->marker_list = NULL;
      } else {
        cinfo->global_state = CSTATE_START;
      }
    }

    /*
     * Destruction of a JPEG object.
     *
     * Everything gets deallocated except the master jpeg_compress_struct itself
     * and the error manager struct.  Both of these are supplied by the application
     * and must be freed, if necessary, by the application.  (Often they are on
     * the stack and so don't need to be freed anyway.)
     * Closing a data source or destination, if necessary, is the application's
     * responsibility.
     */

    GLOBAL(void)
    jpeg_destroy (j_common_ptr cinfo)
    {
      /* We need only tell the memory manager to release everything. */
      /* NB: mem pointer is NULL if memory mgr failed to initialize. */
      if (cinfo->mem != NULL)
        (*cinfo->mem->self_destruct) (cinfo);
      cinfo->mem = NULL;		/* be safe if jpeg_destroy is called twice */
      cinfo->global_state = 0;	/* mark it destroyed */
    }

    /*
     * Convenience routines for allocating quantization and Huffman tables.
     * (Would jutils.c be a more reasonable place to put these?)
     */

    GLOBAL(JQUANT_TBL *)
    jpeg_alloc_quant_table (j_common_ptr cinfo)
    {
      JQUANT_TBL *tbl;

      tbl = (JQUANT_TBL *)
        (*cinfo->mem->alloc_small) (cinfo, JPOOL_PERMANENT, SIZEOF(JQUANT_TBL));
      tbl->sent_table = FALSE;	/* make sure this is false in any new table */
      return tbl;
    }

    GLOBAL(JHUFF_TBL *)
    jpeg_alloc_huff_table (j_common_ptr cinfo)
    {
      JHUFF_TBL *tbl;

      tbl = (JHUFF_TBL *)
        (*cinfo->mem->alloc_small) (cinfo, JPOOL_PERMANENT, SIZEOF(JHUFF_TBL));
      tbl->sent_table = FALSE;	/* make sure this is false in any new table */
      return tbl;
    }