Optimize hash map % to &

1 files changed, 6 insertions, 6 deletions

diff --git a/src/graphics/font_char_map.c b/src/graphics/font_char_map.c
index 64c4674..fc1c2e5 100644
--- a/src/graphics/font_char_map.c
+++ b/src/graphics/font_char_map.c
@@ -1,8 +1,6 @@
 #include "../../include/mgl/graphics/font_char_map.h"
 #include <stdlib.h>
 
-/* TODO: Optimize % to & */
-
 /* Optimized div by sizeof(mgl_font_char_entry*) */
 #if INTPTR_MAX == INT64_MAX
 #define CAP_NUM_ENTRIES(cap) ((cap) >> 3)
@@ -12,6 +10,8 @@
 #error Unsupported system. Only systems where a pointer is 32-bits or 64-bits are supported.
 #endif
 
+#define HASH_TO_INDEX(hash) (hash & (CAP_NUM_ENTRIES(self->capacity)-1))
+
 /* |align| should be a multiple of 2 */
 static size_t align_to(size_t value, size_t align) {
     const size_t is_aligned = (value & (align - 1));
@@ -47,7 +47,7 @@ static void mgl_font_char_map_reorder_nodes(mgl_font_char_map *self, size_t prev
         mgl_font_char_entry *prev_entry = NULL;
         while(entry) {
             const uint32_t hash = entry->key;
-            const size_t index = hash % CAP_NUM_ENTRIES(self->capacity);
+            const size_t index = HASH_TO_INDEX(hash);
             mgl_font_char_entry *next_entry = entry->next; /* store next here so the next insert below doesn't cause an infinite loop */
 
             if(index != i) {
@@ -77,7 +77,7 @@ static int mgl_font_char_map_ensure_capacity(mgl_font_char_map *self, size_t tar
         capacity = 8;
 
     while(capacity < target_capacity) {
-        capacity = capacity + (capacity >> 1); /* *= 1.5 = 1 + 0.5 */
+        capacity = capacity + (capacity >> 1); /* *= 1.5 */
     }
 
     capacity = align_to(capacity, sizeof(mgl_font_char_entry*));
@@ -124,7 +124,7 @@ int mgl_font_char_map_insert(mgl_font_char_map *self, uint32_t key, const mgl_fo
 
     ++self->size;
     const uint32_t hash = key;
-    const size_t index = hash % CAP_NUM_ENTRIES(self->capacity);
+    const size_t index = HASH_TO_INDEX(hash);
 
     mgl_font_char_entry *entry = malloc(sizeof(mgl_font_char_entry));
     if(!entry)
@@ -144,7 +144,7 @@ mgl_font_char_entry* mgl_font_char_map_get(const mgl_font_char_map *self, uint32
         return NULL;
 
     const uint32_t hash = key;
-    const size_t index = hash % CAP_NUM_ENTRIES(self->capacity);
+    const size_t index = HASH_TO_INDEX(hash);
 
     mgl_font_char_entry *entry = self->entries[index];
     while(entry) {