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root |
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#ifndef SHSTR_H__ |
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#define SHSTR_H__ |
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/* The size of the shared strings hashtable. This must be smaller than |
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* 32767, but 947 ought to be plenty enough. |
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*/ |
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#define TABLESIZE 4133 |
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/* This specifies how many characters the hashing routine should look at. |
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* You may actually save CPU by increasing this number if the typical string |
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* is large. |
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*/ |
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#ifndef MAXSTRING |
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#define MAXSTRING 20 |
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#endif |
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/* In the unlikely occurence that 16383 references to a string are too |
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* few, you can modify the below type to something bigger. |
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* (The top bit of "refcount" is used to signify that "u.array" points |
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* at the array entry.) |
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*/ |
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#define REFCOUNT_TYPE int |
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/* The offsetof macro is part of ANSI C, but many compilers lack it, for |
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* example "gcc -ansi" |
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*/ |
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#if !defined (offsetof) |
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#define offsetof(type, member) (int)&(((type *)0)->member) |
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#endif |
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/* SS(string) will return the address of the shared_string struct which |
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* contains "string". |
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*/ |
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#define SS(x) ((shared_string *) ((x) - offsetof(shared_string, string))) |
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#define SS_STATISTICS |
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#define SS_DUMP_TABLE 1 |
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#define SS_DUMP_TOTALS 2 |
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#ifdef SS_STATISTICS |
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static struct statistics { |
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int calls; |
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int hashed; |
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int strcmps; |
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int search; |
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int linked; |
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} add_stats, add_ref_stats, free_stats, find_stats, hash_stats; |
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#define GATHER(n) (++n) |
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#else /* !SS_STATISTICS */ |
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#define GATHER(n) |
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#endif /* SS_STATISTICS */ |
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#define TOPBIT ((unsigned REFCOUNT_TYPE) 1 << (sizeof(REFCOUNT_TYPE) * CHAR_BIT - 1)) |
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#define PADDING ((2 * sizeof(long) - sizeof(REFCOUNT_TYPE)) % sizeof(long)) + 1 |
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typedef struct _shared_string { |
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union { |
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root |
1.3 |
struct _shared_string **array; |
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struct _shared_string *previous; |
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root |
1.1 |
} u; |
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struct _shared_string *next; |
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/* The top bit of "refcount" is used to signify that "u.array" points |
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* at the array entry. |
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*/ |
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unsigned REFCOUNT_TYPE refcount; |
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/* Padding will be unused memory, since we can't know how large |
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* the padding when allocating memory. We assume here that |
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* sizeof(long) is a good boundary. |
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*/ |
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char string[PADDING]; |
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} shared_string; |
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1.2 |
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extern void init_hash_table(void); |
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extern const char *add_string(const char *str); |
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extern const char *add_refcount(const char *str); |
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extern int query_refcount(const char *str); |
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extern const char *find_string(const char *str); |
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extern void free_string(const char *str); |
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extern void ss_dump_statistics(void); |
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extern const char *ss_dump_table(int what); |
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extern int buf_overflow(const char *buf1, const char *buf2, int bufsize); |
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#endif |
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