46 lines
1.4 KiB
Plaintext
46 lines
1.4 KiB
Plaintext
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/* $Header$ */
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/* IDENTIFIER DESCRIPTOR */
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#include "nopp.h"
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/* Since the % operation in the calculation of the hash function
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turns out to be expensive, it is replaced by the cheaper XOR (^).
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Each character of the identifier is xored with an 8-bit mask which
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depends on the position of the character; the sum of these results
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is the hash value. The random masks are obtained from a
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congruence generator in idf.c.
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*/
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#define HASHSIZE 256 /* must be a power of 2 */
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#define HASH_X 0253 /* Knuth's X */
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#define HASH_A 77 /* Knuth's a */
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#define HASH_C 153 /* Knuth's c */
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extern char hmask[]; /* the random masks */
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#define HASHMASK (HASHSIZE-1) /* since it is a power of 2 */
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#define STARTHASH() (0)
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#define ENHASH(hs,ch,ps) (hs + (ch ^ hmask[ps]))
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#define STOPHASH(hs) (hs & HASHMASK)
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struct idf {
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struct idf *next;
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char *id_text;
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#ifndef NOPP
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struct macro *id_macro;
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int id_resmac; /* if nonzero: keyword of macroproc. */
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#endif NOPP
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int id_reserved; /* non-zero for reserved words */
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struct def *id_def; /* variables, typedefs, enum-constants */
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struct sdef *id_sdef; /* selector tags */
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struct tag *id_struct; /* struct and union tags */
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struct tag *id_enum; /* enum tags */
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int id_special; /* special action needed at occurrence */
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};
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/* ALLOCDEF "idf" */
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extern struct idf *str2idf(), *idf_hashed();
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extern int level;
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extern struct idf *gen_idf();
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