add hashtest

hashtest.c

@@ -0,0 +1,106 @@
+/*
+ * Copyright 2022 Edward V. Emelianov <edward.emelianoff@gmail.com>.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+// RUN: gcc -lusefull_macros hashtest.c -o hashtest && time ./hashtest En_words 
+// check hashes for all words in given dictionary and show words with similar hashes
+
+#include <stdio.h>
+#include <string.h>
+#include <usefull_macros.h>
+
+#define ALLOCSZ     (5000)
+
+//#if 0
+// djb2 http://www.cse.yorku.ca/~oz/hash.html
+static uint32_t hash(const char *str){
+    uint32_t hash = 5381;
+    uint32_t c;
+    while((c = (uint32_t)*str++))
+        hash = ((hash << 5) + hash) + c;
+        // hash = hash * 19 + c;
+        //hash = hash * 33 + c;
+    return hash;
+}
+//#endif
+#if 0
+static uint32_t hash(const char *str){ // sdbm
+    uint32_t hash = 5381;
+    uint32_t c;
+    while((c = (uint32_t)*str++))
+        hash = c + (hash << 6) + (hash << 16) - hash;
+    return hash;
+}
+#endif
+
+
+typedef struct{
+    char str[32];
+    uint32_t hash;
+} strhash;
+
+static int sorthashes(const void *a, const void *b){
+    strhash *h1 = (strhash*)a, *h2 = (strhash*)b;
+    return strcmp(h1->str, h2->str);
+}
+
+int main(int argc, char **argv){
+    //char buf[32];
+    initial_setup();
+    if(argc != 2) ERRX("Usage: %s dictionary_file", argv[0]);
+    mmapbuf *b = My_mmap(argv[1]);
+    if(!b) ERRX("Can't open %s", argv[1]);
+    char *word = b->data;
+    strhash *H = MALLOC(strhash, ALLOCSZ);
+    int l = ALLOCSZ, idx = 0;
+    while(*word){
+        if(idx >= l){
+            l += ALLOCSZ;
+            H = realloc(H, sizeof(strhash) * l);
+            if(!H) ERR("realloc()");
+        }
+        char *nxt = strchr(word, '\n');
+        if(nxt){
+            int len = nxt - word;
+            if(len > 31) len = 31;
+            strncpy(H[idx].str, word, len);
+            H[idx].str[len] = 0;
+            //strncpy(buf, word, len);
+            //buf[len] = 0;
+        }else{
+            //snprintf(buf, 31, "%s", word);
+            snprintf(H[idx].str, 31, "%s", word);
+        }
+        H[idx].hash = hash(H[idx].str);
+        //printf("word: %s\n", buf);
+        //printf("%u\t%s\n", hash(buf), buf);
+        //printf("%u\t%s\n", H[idx].hash, H[idx].str);
+        ++idx;
+        if(!nxt) break;
+        word = nxt + 1;
+    }
+    qsort(H, idx, sizeof(strhash), sorthashes);
+    --idx;
+    strhash *p = H;
+    for(int i = 0; i < idx; ++i, ++p){
+        if(p->hash == p[1].hash){
+            printf("Words '%s' and '%s' have same hashes: %u\n", p->str, p[1].str, p->hash);
+        }
+    }
+    FREE(H);
+    My_munmap(b);
+    return 0;
+}