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104 lines
3.1 KiB
C
104 lines
3.1 KiB
C
#include "brt-internal.h"
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#include <assert.h>
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#include <string.h>
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#if 0
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int keycompare (bytevec key1b, ITEMLEN key1len, bytevec key2b, ITEMLEN key2len) {
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const unsigned char *key1 = key1b;
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const unsigned char *key2 = key2b;
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while (key1len > 0 && key2len > 0) {
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unsigned char b1 = key1[0];
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unsigned char b2 = key2[0];
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if (b1<b2) return -1;
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if (b1>b2) return 1;
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key1len--; key1++;
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key2len--; key2++;
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}
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if (key1len<key2len) return -1;
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if (key1len>key2len) return 1;
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return 0;
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}
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#elif 0
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int keycompare (bytevec key1, ITEMLEN key1len, bytevec key2, ITEMLEN key2len) {
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if (key1len==key2len) {
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return memcmp(key1,key2,key1len);
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} else if (key1len<key2len) {
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int r = memcmp(key1,key2,key1len);
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if (r<=0) return -1; /* If the keys are the same up to 1's length, then return -1, since key1 is shorter than key2. */
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else return 1;
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} else {
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return -keycompare(key2,key2len,key1,key1len);
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}
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}
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#elif 0
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int keycompare (bytevec key1, ITEMLEN key1len, bytevec key2, ITEMLEN key2len) {
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if (key1len==key2len) {
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return memcmp(key1,key2,key1len);
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} else if (key1len<key2len) {
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int r = memcmp(key1,key2,key1len);
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if (r<=0) return -1; /* If the keys are the same up to 1's length, then return -1, since key1 is shorter than key2. */
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else return 1;
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} else {
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int r = memcmp(key1,key2,key2len);
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if (r>=0) return 1; /* If the keys are the same up to 2's length, then return 1 since key1 is longer than key2 */
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else return -1;
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}
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}
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#elif 0
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/* This one looks tighter, but it does use memcmp... */
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int keycompare (bytevec key1, ITEMLEN key1len, bytevec key2, ITEMLEN key2len) {
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int comparelen = key1len<key2len ? key1len : key2len;
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const unsigned char *k1;
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const unsigned char *k2;
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for (k1=key1, k2=key2;
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comparelen>0;
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k1++, k2++, comparelen--) {
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if (*k1 != *k2) {
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return (int)*k1-(int)*k2;
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}
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}
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return key1len-key2len;
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}
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#else
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/* unroll that one twice */
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int keycompare (bytevec key1, ITEMLEN key1len, bytevec key2, ITEMLEN key2len) {
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int comparelen = key1len<key2len ? key1len : key2len;
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const unsigned char *k1;
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const unsigned char *k2;
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for (k1=key1, k2=key2;
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comparelen>4;
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k1+=4, k2+=4, comparelen-=4) {
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{ int v1=k1[0], v2=k2[0]; if (v1!=v2) return v1-v2; }
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{ int v1=k1[1], v2=k2[1]; if (v1!=v2) return v1-v2; }
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{ int v1=k1[2], v2=k2[2]; if (v1!=v2) return v1-v2; }
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{ int v1=k1[3], v2=k2[3]; if (v1!=v2) return v1-v2; }
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}
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for (;
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comparelen>0;
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k1++, k2++, comparelen--) {
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if (*k1 != *k2) {
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return (int)*k1-(int)*k2;
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}
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}
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return key1len-key2len;
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}
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#endif
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void test_keycompare (void) {
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assert(keycompare("a",1, "a",1)==0);
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assert(keycompare("aa",2, "a",1)>0);
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assert(keycompare("a",1, "aa",2)<0);
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assert(keycompare("b",1, "aa",2)>0);
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assert(keycompare("aa",2, "b",1)<0);
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assert(keycompare("aaaba",5, "aaaba",5)==0);
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assert(keycompare("aaaba",5, "aaaaa",5)>0);
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assert(keycompare("aaaaa",5, "aaaba",5)<0);
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assert(keycompare("aaaaa",3, "aaaba",3)==0);
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}
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int default_compare_fun (DB *db __attribute__((__unused__)), const DBT *a, const DBT*b) {
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return keycompare(a->data, a->size, b->data, b->size);
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}
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