/*
 * jdatadst-tj.c
 *
 * This file was part of the Independent JPEG Group's software:
 * Copyright (C) 1994-1996, Thomas G. Lane.
 * Modified 2009-2012 by Guido Vollbeding.
 * libjpeg-turbo Modifications:
 * Copyright (C) 2011, 2014, 2016, D. R. Commander.
 * For conditions of distribution and use, see the accompanying README.ijg
 * file.
 *
 * This file contains compression data destination routines for the case of
 * emitting JPEG data to memory or to a file (or any stdio stream).
 * While these routines are sufficient for most applications,
 * some will want to use a different destination manager.
 * IMPORTANT: we assume that fwrite() will correctly transcribe an array of
 * JOCTETs into 8-bit-wide elements on external storage.  If char is wider
 * than 8 bits on your machine, you may need to do some tweaking.
 */

/* this is not a core library module, so it doesn't define JPEG_INTERNALS */
#include "jinclude.h"
#include "jpeglib.h"
#include "jerror.h"

#ifndef HAVE_STDLIB_H           /* <stdlib.h> should declare malloc(),free() */

extern void *malloc(size_t size);

extern void free(void *ptr);

#endif


#define OUTPUT_BUF_SIZE  4096   /* choose an efficiently fwrite'able size */


/* Expanded data destination object for memory output */

typedef struct {
	struct jpeg_destination_mgr pub; /* public fields */

	unsigned char **outbuffer;    /* target buffer */
	unsigned long *outsize;
	unsigned char *newbuffer;     /* newly allocated buffer */
	JOCTET *buffer;               /* start of buffer */
	size_t bufsize;
	boolean alloc;
} my_mem_destination_mgr;

typedef my_mem_destination_mgr *my_mem_dest_ptr;


/*
 * Initialize destination --- called by jpeg_start_compress
 * before any data is actually written.
 */

METHODDEF(void)
init_mem_destination(j_compress_ptr cinfo) {
	/* no work necessary here */
}


/*
 * Empty the output buffer --- called whenever buffer fills up.
 *
 * In typical applications, this should write the entire output buffer
 * (ignoring the current state of next_output_byte & free_in_buffer),
 * reset the pointer & count to the start of the buffer, and return TRUE
 * indicating that the buffer has been dumped.
 *
 * In applications that need to be able to suspend compression due to output
 * overrun, a FALSE return indicates that the buffer cannot be emptied now.
 * In this situation, the compressor will return to its caller (possibly with
 * an indication that it has not accepted all the supplied scanlines).  The
 * application should resume compression after it has made more room in the
 * output buffer.  Note that there are substantial restrictions on the use of
 * suspension --- see the documentation.
 *
 * When suspending, the compressor will back up to a convenient restart point
 * (typically the start of the current MCU). next_output_byte & free_in_buffer
 * indicate where the restart point will be if the current call returns FALSE.
 * Data beyond this point will be regenerated after resumption, so do not
 * write it out when emptying the buffer externally.
 */

METHODDEF(boolean)
empty_mem_output_buffer(j_compress_ptr cinfo) {
	size_t nextsize;
	JOCTET *nextbuffer;
	my_mem_dest_ptr dest = (my_mem_dest_ptr) cinfo->dest;

	if (!dest->alloc) ERREXIT(cinfo, JERR_BUFFER_SIZE);

	/* Try to allocate new buffer with double size */
	nextsize = dest->bufsize * 2;
	nextbuffer = (JOCTET *) malloc(nextsize);

	if (nextbuffer == NULL)
		ERREXIT1(cinfo, JERR_OUT_OF_MEMORY, 10);

	MEMCOPY(nextbuffer, dest->buffer, dest->bufsize);

	if (dest->newbuffer != NULL)
		free(dest->newbuffer);

	dest->newbuffer = nextbuffer;

	dest->pub.next_output_byte = nextbuffer + dest->bufsize;
	dest->pub.free_in_buffer = dest->bufsize;

	dest->buffer = nextbuffer;
	dest->bufsize = nextsize;

	return TRUE;
}


/*
 * Terminate destination --- called by jpeg_finish_compress
 * after all data has been written.  Usually needs to flush buffer.
 *
 * NB: *not* called by jpeg_abort or jpeg_destroy; surrounding
 * application must deal with any cleanup that should happen even
 * for error exit.
 */

METHODDEF(void)
term_mem_destination(j_compress_ptr cinfo) {
	my_mem_dest_ptr dest = (my_mem_dest_ptr) cinfo->dest;

	if (dest->alloc) *dest->outbuffer = dest->buffer;
	*dest->outsize = (unsigned long) (dest->bufsize - dest->pub.free_in_buffer);
}


/*
 * Prepare for output to a memory buffer.
 * The caller may supply an own initial buffer with appropriate size.
 * Otherwise, or when the actual data output exceeds the given size,
 * the library adapts the buffer size as necessary.
 * The standard library functions malloc/free are used for allocating
 * larger memory, so the buffer is available to the application after
 * finishing compression, and then the application is responsible for
 * freeing the requested memory.
 */

GLOBAL(void)
jpeg_mem_dest_tj(j_compress_ptr cinfo,
                 unsigned char **outbuffer, unsigned long *outsize,
                 boolean alloc) {
	boolean reused = FALSE;
	my_mem_dest_ptr dest;

	if (outbuffer == NULL || outsize == NULL)     /* sanity check */
		ERREXIT(cinfo, JERR_BUFFER_SIZE);

	/* The destination object is made permanent so that multiple JPEG images
	 * can be written to the same buffer without re-executing jpeg_mem_dest.
	 */
	if (cinfo->dest == NULL) {    /* first time for this JPEG object? */
		cinfo->dest = (struct jpeg_destination_mgr *)
				(*cinfo->mem->alloc_small)((j_common_ptr) cinfo, JPOOL_PERMANENT,
				                           sizeof(my_mem_destination_mgr));
		dest = (my_mem_dest_ptr) cinfo->dest;
		dest->newbuffer = NULL;
		dest->buffer = NULL;
	} else if (cinfo->dest->init_destination != init_mem_destination) {
		/* It is unsafe to reuse the existing destination manager unless it was
		 * created by this function.
		 */
		ERREXIT(cinfo, JERR_BUFFER_SIZE);
	}

	dest = (my_mem_dest_ptr) cinfo->dest;
	dest->pub.init_destination = init_mem_destination;
	dest->pub.empty_output_buffer = empty_mem_output_buffer;
	dest->pub.term_destination = term_mem_destination;
	if (dest->buffer == *outbuffer && *outbuffer != NULL && alloc)
		reused = TRUE;
	dest->outbuffer = outbuffer;
	dest->outsize = outsize;
	dest->alloc = alloc;

	if (*outbuffer == NULL || *outsize == 0) {
		if (alloc) {
			/* Allocate initial buffer */
			dest->newbuffer = *outbuffer = (unsigned char *) malloc(OUTPUT_BUF_SIZE);
			if (dest->newbuffer == NULL)
				ERREXIT1(cinfo, JERR_OUT_OF_MEMORY, 10);
			*outsize = OUTPUT_BUF_SIZE;
		} else
			ERREXIT(cinfo, JERR_BUFFER_SIZE);
	}

	dest->pub.next_output_byte = dest->buffer = *outbuffer;
	if (!reused)
		dest->bufsize = *outsize;
	dest->pub.free_in_buffer = dest->bufsize;
}
