rtai_shm.h

Linux共享内存share memory通信机制的内核实现

/*
COPYRIGHT (C) 1999  Paolo Mantegazza ([e-mail])

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
*/


#define REAL_SIZE(x) (((x) - 1) & PAGE_MASK) + PAGE_SIZE

extern void *rtai_kmalloc_f(int name, int size, unsigned long pid);
#define rtai_kmalloc(x, y)  rtai_kmalloc_f((x), (y), (unsigned long)(&(__this_module)));

extern void rtai_kfree_f(int name, unsigned long pid);
#define rtai_kfree(x)    rtai_kfree_f((x), (unsigned long)(&(__this_module)));

static inline unsigned long nam2num(const char *name)
{
	int i = 0;
	union { struct { long num; char eos; } num; char name[5]; } retval;
	if (!name[0]) {
	   return 0x454e4f4e;  // "NULL"
	}
	retval.num.eos = 0;
	while (i < 4 && (retval.name[i] = name[i])) { i++; }
	return retval.num.num;
}

static inline void num2nam(unsigned long num, char *name)
{
	int i = 0;
	union { struct { long num; char eos; } num; char name[5]; } retval;
	retval.num.num = num;
	retval.num.eos = 0;
	while (i < 4 && (name[i] = retval.name[i])) { i++; }
}


#ifndef MODULE
#include <asm/page.h>

static void *rtai_malloc(unsigned long name, int size)
{
	void *adr;
	int hook;
	struct { unsigned long name, size; } arg;
	if (size <= 0) {
		return 0;
	}
	if ((hook = open("/dev/rtai_shm", O_RDWR)) < 0) {
		return 0;
	}
	arg.name = name;
	arg.size = size;
	if (!(size = ioctl(hook, 1, (unsigned long)(&arg)))) {
		return 0;
	}
	adr = mmap(NULL, size, PROT_WRITE|PROT_READ, MAP_SHARED|MAP_FILE, hook, 0);

// the if-else below is just for testing 
	{
		if ((size = ioctl(hook, 4, name)) < 0) {
			printf("REAL ALLOCATION OF %d BYTES FOR %lx.\n", -size, name); 
		} else {
			printf("JUST A REMAP OF %d BYTES FOR %lx.\n", size, name); 
		}
	}

	close(hook);

	return adr;
}

static inline void rtai_free(int name, void *adr)
{
	int size, hook;
	if ((size = ioctl(hook = open("/dev/rtai_shm", O_RDWR), 2, name))) {

// the if-else below is just for testing 
		{
			int lsize;
			if ((lsize = ioctl(hook, 4, name)) < 0) {
				printf("FREED %d BYTES OF %lx.\n", -lsize, name);
			} else {
				printf("UNMAPPED %d BYTES OF %lx.\n", lsize, name);
			}
		}

		munmap(adr, size);
		ioctl(hook, 3, name);
	}
	close(hook);
}

// all what's below is just for testing

static inline void rtai_check(unsigned long name)
{
	int hook; 
	ioctl(hook = open("/dev/rtai_shm", O_RDWR), 5, name);
	close(hook);
}

static inline int rtai_is_closable(void)
{
	int hook, retval; 
	retval = ioctl(hook = open("/dev/rtai_shm", O_RDWR), 6, 0);
	close(hook);
	return retval;
}

static inline void rtai_make_closable(void)
{
	int hook; 
	ioctl(hook = open("/dev/rtai_shm", O_RDWR), 7, 0);
	close(hook);
}

static inline void rtai_not_closable(void)
{
	int hook; 
	ioctl(hook = open("/dev/rtai_shm", O_RDWR), 8, 0);
	close(hook);
}
#endif