ack/lang/cem/cemcom.ansi/idf.str
1989-02-07 11:04:05 +00:00

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/*
* (c) copyright 1987 by the Vrije Universiteit, Amsterdam, The Netherlands.
* See the copyright notice in the ACK home directory, in the file "Copyright".
*/
/* $Header$ */
/* IDENTIFIER DESCRIPTOR */
#include "nopp.h"
/* Since the % operation in the calculation of the hash function
turns out to be expensive, it is replaced by the cheaper XOR (^).
Each character of the identifier is xored with an 8-bit mask which
depends on the position of the character; the sum of these results
is the hash value. The random masks are obtained from a
congruence generator in idf.c.
*/
#define HASHSIZE 256 /* must be a power of 2 */
#define HASH_X 0253 /* Knuth's X */
#define HASH_A 77 /* Knuth's a */
#define HASH_C 153 /* Knuth's c */
extern char hmask[]; /* the random masks */
#define HASHMASK (HASHSIZE-1) /* since it is a power of 2 */
#define STARTHASH() (0)
#define ENHASH(hs,ch,ps) (hs + (ch ^ hmask[ps]))
#define STOPHASH(hs) (hs & HASHMASK)
struct idf {
struct idf *next;
char *id_text;
#ifndef NOPP
struct macro *id_macro;
int id_resmac; /* if nonzero: keyword of macroproc. */
#endif NOPP
int id_reserved; /* non-zero for reserved words */
char *id_file; /* file containing the occurrence */
unsigned int id_line; /* line number of the occurrence */
struct def *id_def; /* variables, typedefs, enum-constants */
struct sdef *id_sdef; /* selector tags */
struct tag *id_struct; /* struct and union tags */
struct tag *id_enum; /* enum tags */
int id_proto; /* non-zero don't complain about proto */
int id_special; /* special action needed at occurrence */
};
/* ALLOCDEF "idf" 50 */
extern struct idf *str2idf(), *idf_hashed();
extern int level;
extern struct idf *gen_idf();