minix/kernel/ipc.h

#ifndef IPC_H
#define IPC_H

/* This header file defines constants for MINIX inter-process communication.
 * These definitions are used in the file proc.c.
 */
#include <minix/com.h>

/* Masks and flags for system calls. */
#define SYSCALL_FUNC	0x0F	/* mask for system call function */
#define SYSCALL_FLAGS   0xF0    /* mask for system call flags */
#define NON_BLOCKING    0x10	/* prevent blocking, return error */

/* System call numbers that are passed when trapping to the kernel. The 
 * numbers are carefully defined so that it can easily be seen (based on 
 * the bits that are on) which checks should be done in sys_call().
 */
#define SEND		   1	/* 0 0 0 1 : blocking send */
#define RECEIVE		   2	/* 0 0 1 0 : blocking receive */
#define SENDREC	 	   3  	/* 0 0 1 1 : SEND + RECEIVE */
#define NOTIFY		   4	/* 0 1 0 0 : nonblocking notify */
#define ECHO		   8	/* 1 0 0 0 : echo a message */

/* The following bit masks determine what checks that should be done. */
#define CHECK_PTR       0x0B	/* 1 0 1 1 : validate message buffer */
#define CHECK_DST       0x05	/* 0 1 0 1 : validate message destination */
#define CHECK_SRC       0x02	/* 0 0 1 0 : validate message source */
#define CHECK_DEADLOCK  0x03	/* 0 0 1 1 : check for deadlock */

#endif /* IPC_H */