pnm_cod.c

JPEG2000是以小波变换为基础

/*
 * Copyright (c) 1999-2000 Image Power, Inc. and the University of
 *   British Columbia.
 * Copyright (c) 2001-2002 Michael David Adams.
 * All rights reserved.
 */

/* __START_OF_JASPER_LICENSE__
 * 
 * JasPer License Version 2.0
 * 
 * Copyright (c) 2001-2006 Michael David Adams
 * Copyright (c) 1999-2000 Image Power, Inc.
 * Copyright (c) 1999-2000 The University of British Columbia
 * 
 * All rights reserved.
 * 
 * Permission is hereby granted, free of charge, to any person (the
 * "User") obtaining a copy of this software and associated documentation
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 * 1.  The above copyright notices and this permission notice (which
 * includes the disclaimer below) shall be included in all copies or
 * substantial portions of the Software.
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 * 2.  The name of a copyright holder shall not be used to endorse or
 * promote products derived from the Software without specific prior
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 * THIS DISCLAIMER OF WARRANTY CONSTITUTES AN ESSENTIAL PART OF THIS
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/*
 * Portable Pixmap/Graymap Format Support
 *
 * $Id$
 */

/******************************************************************************\
* Includes.
\******************************************************************************/

#include <ctype.h>
#include <math.h>
#include <stdlib.h>
#include <assert.h>

#include "jasper/jas_math.h"

#include "pnm_cod.h"

/******************************************************************************\
* Miscellaneous utilities.
\******************************************************************************/

/* Determine the PNM type (i.e., PGM or PPM) from the magic number. */
int pnm_type(uint_fast16_t magic)
{
	int type;
	switch (magic) {
	case PNM_MAGIC_TXTPPM:
	case PNM_MAGIC_BINPPM:
		type = PNM_TYPE_PPM;
		break;
	case PNM_MAGIC_TXTPGM:
	case PNM_MAGIC_BINPGM:
		type = PNM_TYPE_PGM;
		break;
	case PNM_MAGIC_TXTPBM:
	case PNM_MAGIC_BINPBM:
		type = PNM_TYPE_PBM;
		break;
	default:
		/* This should not happen. */
		abort();
		break;
	}
	return type;
}

/* Determine the PNM format (i.e., text or binary) from the magic number. */
int pnm_fmt(uint_fast16_t magic)
{
	int fmt;
	switch (magic) {
	case PNM_MAGIC_TXTPBM:
	case PNM_MAGIC_TXTPGM:
	case PNM_MAGIC_TXTPPM:
		fmt = PNM_FMT_TXT;
		break;
	case PNM_MAGIC_BINPBM:
	case PNM_MAGIC_BINPGM:
	case PNM_MAGIC_BINPPM:
		fmt = PNM_FMT_BIN;
		break;
	default:
		/* This should not happen. */
		abort();
		break;
	}
	return fmt;
}

/* Determine the depth (i.e., precision) from the maximum value. */
int pnm_maxvaltodepth(uint_fast32_t maxval)
{
	int n;

	n = 0;
	while (maxval > 0) {
		maxval >>= 1;
		++n;
	}
	return n;
}