Improve bitmap efficiency and tests

prrt/util/bitmap.c

@@ -28,31 +28,70 @@ Bitmap *Bitmap_create(bool initialValue, uint32_t elementCount)
 
 void Bitmap_set_range_0(Bitmap *bitmap, uint32_t start, uint32_t length)
 {
-    uint32_t i = 0;
-    // TODO: highly inefficient - optimize
-	for(i = 0; i < length; i++) {
-		Bitmap_set_0(bitmap, start + i);
-	}
+    uint32_t start_byte = start / 32;
+    uint32_t start_bit = start % 32;
+    uint32_t end_byte = (start + length) / 32;
+    uint32_t end_bit = (start + length) % 32;
+    uint32_t full_mask = ~0u;
+
+    if (start_byte == end_byte) {
+        uint32_t mask = (full_mask << end_bit) ^ (full_mask << start_bit);
+        bitmap->data[start_byte] ^= (bitmap->data[start_byte] & mask);
+    } else {
+        uint32_t start_mask = full_mask << start_bit;
+        bitmap->data[start_byte] ^= (bitmap->data[start_byte] & start_mask);
+        for (uint32_t current_byte = start_byte + 1; current_byte < end_byte; ++current_byte) {
+            bitmap->data[current_byte] = 0;
+        }
+        uint32_t end_mask = ~(full_mask << end_bit);
+        bitmap->data[end_byte] ^= (bitmap->data[end_byte] & end_mask);
+    }
 }
 
 void Bitmap_set_range_1(Bitmap *bitmap, uint32_t start, uint32_t length)
 {
-    uint32_t i = 0;
-    // TODO: highly inefficient - optimize
-	for(i = 0; i < length; i++) {
-		Bitmap_set_1(bitmap, start + i);
-	}
+    uint32_t start_byte = start / 32;
+    uint32_t start_bit = start % 32;
+    uint32_t end_byte = (start + length) / 32;
+    uint32_t end_bit = (start + length) % 32;
+    uint32_t full_mask = ~0u;
+
+    if (start_byte == end_byte) {
+        uint32_t mask = (full_mask << end_bit) ^ (full_mask << start_bit);
+        bitmap->data[start_byte] |= mask;
+    } else {
+        uint32_t start_mask = full_mask << start_bit;
+        bitmap->data[start_byte] |= start_mask;
+        for (uint32_t current_byte = start_byte + 1; current_byte < end_byte; ++current_byte) {
+            bitmap->data[current_byte] = full_mask;
+        }
+        uint32_t end_mask = ~(full_mask << end_bit);
+        bitmap->data[end_byte] |= end_mask;
+    }
 }
 
 uint32_t Bitmap_sum_ones(Bitmap *bitmap, uint32_t start, uint32_t length)
 {
-    uint32_t sum = 0;
-    uint32_t i = 0;
-    // TODO: highly inefficient - optimize
-    for(i = 0; i < length; i++) {
-        sum += (Bitmap_get(bitmap, start + i) == true);
+    uint32_t start_byte = start / 32;
+    uint32_t start_bit = start % 32;
+    uint32_t end_byte = (start + length) / 32;
+    uint32_t end_bit = (start + length) % 32;
+    uint32_t full_mask = ~0u;
+
+    if (start_byte == end_byte) {
+        uint32_t mask = (full_mask << end_bit) ^ (full_mask << start_bit);
+        return __builtin_popcount(bitmap->data[start_byte] & mask);
+    } else {
+        uint32_t start_mask = full_mask << start_bit;
+        uint32_t sum = __builtin_popcount(bitmap->data[start_byte] & start_mask);
+        for (uint32_t current_byte = start_byte + 1; current_byte < end_byte; ++current_byte) {
+            sum += __builtin_popcount(bitmap->data[current_byte]);
+        }
+        uint32_t end_mask = ~(full_mask << end_bit);
+        sum += __builtin_popcount(bitmap->data[end_byte] & end_mask);
+
+        return sum;
     }
-    return sum;
 }
 
 uint32_t Bitmap_sum_zeros(Bitmap *bitmap, uint32_t start, uint32_t length)

tests/bitmap_tests.cpp

@@ -54,12 +54,22 @@ TEST_F(BitmapTest, GetRange)
 
 TEST_F(BitmapTest, SetRange)
 {
-    ASSERT_EQ(5, Bitmap_sum_ones(bitmap, 1, 5));
-    ASSERT_EQ(0, Bitmap_sum_zeros(bitmap, 1, 5));
-    Bitmap_set_range(bitmap, 2, 2, false);
-    ASSERT_FALSE(Bitmap_get(bitmap, 2));
-    ASSERT_FALSE(Bitmap_get(bitmap, 3));
-    ASSERT_TRUE(Bitmap_get(bitmap, 4));
-    ASSERT_EQ(3, Bitmap_sum_ones(bitmap, 1, 5));
-    ASSERT_EQ(2, Bitmap_sum_zeros(bitmap, 1, 5));
+    ASSERT_EQ(500, Bitmap_sum_ones(bitmap, 17, 500));
+    ASSERT_EQ(0, Bitmap_sum_zeros(bitmap, 17, 500));
+
+    Bitmap_set_range(bitmap, 2, 300, false);
+    ASSERT_TRUE(Bitmap_get(bitmap, 1));
+    for (int i = 2; i < 302; ++i) {
+        ASSERT_FALSE(Bitmap_get(bitmap, i));
+    }
+    ASSERT_TRUE(Bitmap_get(bitmap, 302));
+
+    Bitmap_set_range(bitmap, 150, 100, true);
+    ASSERT_FALSE(Bitmap_get(bitmap, 149));
+    for (int i = 150; i < 250; ++i) {
+        ASSERT_TRUE(Bitmap_get(bitmap, i));
+    }
+    ASSERT_FALSE(Bitmap_get(bitmap, 250));
+    ASSERT_EQ(300, Bitmap_sum_ones(bitmap, 1, 500));
+    ASSERT_EQ(200, Bitmap_sum_zeros(bitmap, 1, 500));
 }