Avoid allocating packet buffers unnecessarily.

[meshlink] / src / hash.c

diff --git a/src/hash.c b/src/hash.c
index c2f0903162709a8ab0efea9b9966f2b86efa4a07..a7964428830abefa4f0254a251f3bd7594357e80 100644 (file)
--- a/src/hash.c
+++ b/src/hash.c
@@ -1,6 +1,6 @@
 /*
     hash.c -- hash table management
-    Copyright (C) 2012-2013 Guus Sliepen <guus@meshlink.io>
+    Copyright (C) 2014 Guus Sliepen <guus@meshlink.io>
 
     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
@@ -27,36 +27,44 @@
 static uint32_t hash_function(const void *p, size_t len) {
        const uint8_t *q = p;
        uint32_t hash = 0;
+
        while(true) {
-               for(int i = len > 4 ? 4 : len; --i;)
+               for(int i = len > 4 ? 4 : len; --i;) {
                        hash += q[len - i] << (8 * i);
+               }
+
                hash *= 0x9e370001UL; // Golden ratio prime.
-               if(len <= 4)
+
+               if(len <= 4) {
                        break;
+               }
+
                len -= 4;
        }
+
        return hash;
 }
 
 /* Map 32 bits int onto 0..n-1, without throwing away too many bits if n is 2^8 or 2^16 */
 
 static uint32_t modulo(uint32_t hash, size_t n) {
-       if(n == 0x100)
+       if(n == 0x100) {
                return (hash >> 24) ^ ((hash >> 16) & 0xff) ^ ((hash >> 8) & 0xff) ^ (hash & 0xff);
-       else if(n == 0x10000)
+       } else if(n == 0x10000) {
                return (hash >> 16) ^ (hash & 0xffff);
-       else
+       } else {
                return hash % n;
+       }
 }
 
 /* (De)allocation */
 
 hash_t *hash_alloc(size_t n, size_t size) {
-       hash_t *hash = xzalloc(sizeof *hash);
+       hash_t *hash = xzalloc(sizeof(*hash));
        hash->n = n;
        hash->size = size;
        hash->keys = xzalloc(hash->n * hash->size);
-       hash->values = xzalloc(hash->n * sizeof *hash->values);
+       hash->values = xzalloc(hash->n * sizeof(*hash->values));
        return hash;
 }
 
@@ -76,16 +84,21 @@ void hash_insert(hash_t *hash, const void *key, const void *value) {
 
 void *hash_search(const hash_t *hash, const void *key) {
        uint32_t i = modulo(hash_function(key, hash->size), hash->n);
+
        if(hash->values[i] && !memcmp(key, hash->keys + i * hash->size, hash->size)) {
                return (void *)hash->values[i];
        }
+
        return NULL;
 }
 
 void *hash_search_or_insert(hash_t *hash, const void *key, const void *value) {
        uint32_t i = modulo(hash_function(key, hash->size), hash->n);
-       if(hash->values[i] && !memcmp(key, hash->keys + i * hash->size, hash->size))
+
+       if(hash->values[i] && !memcmp(key, hash->keys + i * hash->size, hash->size)) {
                return (void *)hash->values[i];
+       }
+
        memcpy(hash->keys + i * hash->size, key, hash->size);
        hash->values[i] = value;
        return NULL;
@@ -94,14 +107,15 @@ void *hash_search_or_insert(hash_t *hash, const void *key, const void *value) {
 /* Utility functions */
 
 void hash_clear(hash_t *hash) {
-       memset(hash->values, 0, hash->n * sizeof *hash->values);
+       memset(hash->values, 0, hash->n * sizeof(*hash->values));
 }
 
 void hash_resize(hash_t *hash, size_t n) {
        hash->keys = xrealloc(hash->keys, n * hash->size);
-       hash->values = xrealloc(hash->values, n * sizeof *hash->values);
+       hash->values = xrealloc(hash->values, n * sizeof(*hash->values));
+
        if(n > hash->n) {
                memset(hash->keys + hash->n * hash->size, 0, (n - hash->n) * hash->size);
-               memset(hash->values + hash->n, 0, (n - hash->n) * sizeof *hash->values);
+               memset(hash->values + hash->n, 0, (n - hash->n) * sizeof(*hash->values));
        }
 }