85 lines
1.5 KiB
C
85 lines
1.5 KiB
C
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#ifndef __TTC_KEY_CODEC_H
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#define __TTC_KEY_CODEC_H
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#include <string.h>
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#include <stdint.h>
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#include "namespace.h"
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TTC_BEGIN_NAMESPACE
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class CKeyCodec
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{
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public:
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CKeyCodec(const unsigned t)
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{
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set_key_type(t);
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}
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~CKeyCodec(){}
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void set_key_type(const unsigned t)
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{
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type = t;
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}
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unsigned key_length(const char *ptr)
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{
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return type > 0 ? type : *(unsigned char *)ptr;
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}
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unsigned total_length(const char *ptr)
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{
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return type > 0 ? key_length(ptr) : key_length(ptr)+1;
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}
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const char* key_pointer(const char *ptr)
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{
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//return type > 0 ? ptr : ptr+1;
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return ptr;
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}
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int key_compare(const char *a, const char *b, size_t len)
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{
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switch(type)
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{
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case 1:
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return *(uint8_t *)a - *(uint8_t *)b;
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case 2:
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return *(uint16_t *)a - *(uint16_t *)b;
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case 4:
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return *(uint32_t *)a - *(uint32_t *)b;
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}
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return memcmp(a, b, len);
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}
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unsigned key_hash(const char *ptr, size_t len)
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{
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unsigned hash = 0x123;
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//unsigned len = total_length(ptr);
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do {
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unsigned char c = *ptr++;
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//c = icase_hash(c);
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hash = hash*101 + c;
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} while (--len);
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return hash;
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}
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private:
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/*
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* This removes bit 5 if bit 6 is set. (from git name-hash.c)
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*
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* That will make US-ASCII characters hash to their upper-case
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* equivalent. We could easily do this one whole word at a time,
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* but that's for future worries.
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*/
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static inline unsigned char icase_hash(unsigned char c)
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{
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return c & ~((c & 0x40) >> 1);
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}
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private:
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unsigned type;
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};
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TTC_END_NAMESPACE
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#endif
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