param.h

Newlib 嵌入式 C库 标准实现代码

/*
 *  $Id: param.h,v 1.2 2006/08/28 17:17:24 jjohnstn Exp $
 */

#ifndef _MACHINE_PARAM_H_
#define	_MACHINE_PARAM_H_

/*
 * These aren't really machine-dependent for RTEMS.....
 */

/*
#define MACHINE		"i386"
#define MID_MACHINE	MID_I386
*/

/*
 * Round p (pointer or byte index) up to a correctly-aligned value
 * for all data types (int, long, ...).   The result is unsigned int
 * and must be cast to any desired pointer type.
 */
#define ALIGNBYTES	(sizeof(int) - 1)
#define ALIGN(p)	(((unsigned)(p) + ALIGNBYTES) & ~ALIGNBYTES)

#define PAGE_SHIFT	12		/* LOG2(PAGE_SIZE) */
#define PAGE_SIZE	(1<<PAGE_SHIFT)	/* bytes/page */
#define PAGE_MASK	(PAGE_SIZE-1)
#define NPTEPG		(PAGE_SIZE/(sizeof (pt_entry_t)))

#define NPDEPG		(PAGE_SIZE/(sizeof (pd_entry_t)))
#define PDRSHIFT	22		/* LOG2(NBPDR) */
#define NBPDR		(1<<PDRSHIFT)	/* bytes/page dir */

#define DEV_BSHIFT	9		/* log2(DEV_BSIZE) */
#define DEV_BSIZE	(1<<DEV_BSHIFT)

#if defined(__AVR__) || defined(__h8300__)
#define BLKDEV_IOSIZE	1024
#define MAXPHYS		(1 * 1024)	/* max raw I/O transfer size */
#else
#define BLKDEV_IOSIZE	2048
#define MAXPHYS		(64 * 1024)	/* max raw I/O transfer size */
#endif

#define UPAGES	2		/* pages of u-area */

/*
 * Constants related to network buffer management.
 * MCLBYTES must be no larger than CLBYTES (the software page size), and,
 * on machines that exchange pages of input or output buffers with mbuf
 * clusters (MAPPED_MBUFS), MCLBYTES must also be an integral multiple
 * of the hardware page size.
 */
#ifndef	MSIZE
#define MSIZE		128		/* size of an mbuf */
#endif	/* MSIZE */

#ifndef	MCLSHIFT
#define MCLSHIFT	11		/* convert bytes to m_buf clusters */
#endif	/* MCLSHIFT */
#define MCLBYTES	(1 << MCLSHIFT)	/* size of an m_buf cluster */
#define MCLOFSET	(MCLBYTES - 1)	/* offset within an m_buf cluster */

/*
 * Some macros for units conversion
 */

/* clicks to bytes */
#define ctob(x)	((x)<<PAGE_SHIFT)

/* bytes to clicks */
#define btoc(x)	(((unsigned)(x)+PAGE_MASK)>>PAGE_SHIFT)

/*
 * btodb() is messy and perhaps slow because `bytes' may be an off_t.  We
 * want to shift an unsigned type to avoid sign extension and we don't
 * want to widen `bytes' unnecessarily.  Assume that the result fits in
 * a daddr_t.
 */
#define btodb(bytes)	 		/* calculates (bytes / DEV_BSIZE) */ \
	(sizeof (bytes) > sizeof(long) \
	 ? (daddr_t)((unsigned long long)(bytes) >> DEV_BSHIFT) \
	 : (daddr_t)((unsigned long)(bytes) >> DEV_BSHIFT))

#define dbtob(db)			/* calculates (db * DEV_BSIZE) */ \
	((off_t)(db) << DEV_BSHIFT)

/*
 * Mach derived conversion macros
 */
#define trunc_page(x)		((unsigned)(x) & ~PAGE_MASK)
#define round_page(x)		((((unsigned)(x)) + PAGE_MASK) & ~PAGE_MASK)

#define atop(x)			((unsigned)(x) >> PAGE_SHIFT)
#define ptoa(x)			((unsigned)(x) << PAGE_SHIFT)

#endif /* !_MACHINE_PARAM_H_ */