const.h

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#ifndef CHIP
#error CHIP is not defined
#endif

#define EXTERN        extern    /* used in *.h files */
#define PRIVATE       static    /* PRIVATE x limits the scope of x */
#define PUBLIC                  /* PUBLIC is the opposite of PRIVATE */
#define FORWARD       static    /* some compilers require this to be 'static'*/

#define TRUE               1    /* used for turning integers into Booleans */
#define FALSE              0    /* used for turning integers into Booleans */

#define HZ                60    /* clock freq (software settable on IBM-PC) */

#define SUPER_USER (uid_t) 0    /* uid_t of superuser */

#define NULL     ((void *)0)    /* null pointer */
#define CPVEC_NR          16    /* max # of entries in a SYS_VCOPY request */
#define CPVVEC_NR         64    /* max # of entries in a SYS_VCOPY request */
#define NR_IOREQS       MIN(NR_BUFS, 64)
                                /* maximum number of entries in an iorequest */

/* Message passing constants. */
#define MESS_SIZE (sizeof(message))     /* might need usizeof from FS here */
#define NIL_MESS ((message *) 0)        /* null pointer */

/* Memory related constants. */
#define SEGMENT_TYPE  0xFF00    /* bit mask to get segment type */
#define SEGMENT_INDEX 0x00FF    /* bit mask to get segment index */

#define LOCAL_SEG     0x0000    /* flags indicating local memory segment */
#define NR_LOCAL_SEGS      3    /* # local segments per process (fixed) */
#define T                  0    /* proc[i].mem_map[T] is for text */
#define D                  1    /* proc[i].mem_map[D] is for data */
#define S                  2    /* proc[i].mem_map[S] is for stack */

#define REMOTE_SEG    0x0100    /* flags indicating remote memory segment */
#define NR_REMOTE_SEGS     3    /* # remote memory regions (variable) */

#define BIOS_SEG      0x0200    /* flags indicating BIOS memory segment */
#define NR_BIOS_SEGS       3    /* # BIOS memory regions (variable) */

#define PHYS_SEG      0x0400    /* flag indicating entire physical memory */

/* Labels used to disable code sections for different reasons. */
#define DEAD_CODE          0    /* unused code in normal configuration */
#define FUTURE_CODE        0    /* new code to be activated + tested later */
#define TEMP_CODE          1    /* active code to be removed later */

/* Process name length in the PM process table, including '\0'. */
#define PROC_NAME_LEN   16

/* Miscellaneous */
#define BYTE            0377    /* mask for 8 bits */
#define READING            0    /* copy data to user */
#define WRITING            1    /* copy data from user */
#define NO_NUM        0x8000    /* used as numerical argument to panic() */
#define NIL_PTR   (char *) 0    /* generally useful expression */
#define HAVE_SCATTERED_IO  1    /* scattered I/O is now standard */

/* Macros. */
#define MAX(a, b)   ((a) > (b) ? (a) : (b))
#define MIN(a, b)   ((a) < (b) ? (a) : (b))

/* Memory is allocated in clicks. */
#if (CHIP == INTEL)
#define CLICK_SIZE      4096    /* unit in which memory is allocated */
#define CLICK_SHIFT       12    /* log2 of CLICK_SIZE */
#endif

#if (CHIP == SPARC) || (CHIP == M68000)
#define CLICK_SIZE      4096    /* unit in which memory is allocated */
#define CLICK_SHIFT       12    /* log2 of CLICK_SIZE */
#endif

/* Click to byte conversions (and vice versa). */
#define HCLICK_SHIFT       4    /* log2 of HCLICK_SIZE */
#define HCLICK_SIZE       16    /* hardware segment conversion magic */
#if CLICK_SIZE >= HCLICK_SIZE
#define click_to_hclick(n) ((n) << (CLICK_SHIFT - HCLICK_SHIFT))
#else
#define click_to_hclick(n) ((n) >> (HCLICK_SHIFT - CLICK_SHIFT))
#endif
#define hclick_to_physb(n) ((phys_bytes) (n) << HCLICK_SHIFT)
#define physb_to_hclick(n) ((n) >> HCLICK_SHIFT)

#define ABS             -999    /* this process means absolute memory */

/* Flag bits for i_mode in the inode. */
#define I_TYPE          0170000 /* this field gives inode type */
#define I_SYMBOLIC_LINK 0120000 /* file is a symbolic link */
#define I_REGULAR       0100000 /* regular file, not dir or special */
#define I_BLOCK_SPECIAL 0060000 /* block special file */
#define I_DIRECTORY     0040000 /* file is a directory */
#define I_CHAR_SPECIAL  0020000 /* character special file */
#define I_NAMED_PIPE    0010000 /* named pipe (FIFO) */
#define I_SET_UID_BIT   0004000 /* set effective uid_t on exec */
#define I_SET_GID_BIT   0002000 /* set effective gid_t on exec */
#define ALL_MODES       0006777 /* all bits for user, group and others */
#define RWX_MODES       0000777 /* mode bits for RWX only */
#define R_BIT           0000004 /* Rwx protection bit */
#define W_BIT           0000002 /* rWx protection bit */
#define X_BIT           0000001 /* rwX protection bit */
#define I_NOT_ALLOC     0000000 /* this inode is free */

/* Some limits. */
#define MAX_BLOCK_NR  ((block_t) 077777777)     /* largest block number */
#define HIGHEST_ZONE   ((zone_t) 077777777)     /* largest zone number */
#define MAX_INODE_NR ((ino_t) 037777777777)     /* largest inode number */
#define MAX_FILE_POS ((off_t) 037777777777)     /* largest legal file offset */

#define MAX_SYM_LOOPS   8       /* how many symbolic links are recursed */

#define NO_BLOCK              ((block_t) 0)     /* absence of a block number */
#define NO_ENTRY                ((ino_t) 0)     /* absence of a dir entry */
#define NO_ZONE                ((zone_t) 0)     /* absence of a zone number */
#define NO_DEV                  ((dev_t) 0)     /* absence of a device numb */

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