Make the layer cache more efficient

Also change the internal representation to a one dimensional array

tests/layer_cache/test_layer_cache.cpp

@@ -0,0 +1,140 @@
+/* Copyright 2018 Fred Sundvik
+ *
+ * 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 2 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/>.
+ */
+
+#include "test_common.hpp"
+
+#if MAX_LAYER_BITS != 5
+#error "Tese tests assume that the MAX_LAYER_BITS is equal to 5"
+// If this is changed, change the constants below
+#endif
+
+#if MATRIX_COLS != 2 || MATRIX_ROWS !=2
+#error "These tests assume that the second row starts after the second column"
+#endif
+
+namespace
+{
+  constexpr uint8_t max_layer_value = 0b11111;
+  constexpr uint8_t min_layer_value = 0;
+  constexpr uint8_t alternating_starting_with_1 = 0b10101;
+  constexpr uint8_t alternating_starting_with_0 = 0b01010;
+
+
+  uint8_t read_cache(uint8_t col, uint8_t row) {
+    keypos_t key;
+    key.col = col;
+    key.row =  row;
+    return read_source_layers_cache(key);
+  }
+
+  void write_cache(uint8_t col, uint8_t row, uint8_t value) {
+    keypos_t key;
+    key.col = col;
+    key.row =  row;
+    return update_source_layers_cache(key, value);
+  }
+
+  void fill_cache() {
+    for (int i=0; i < MATRIX_ROWS; i++) {
+      for (int j=0; j < MATRIX_COLS; j++) {
+        write_cache(j, i, max_layer_value);
+      }
+    }
+  }
+
+  void clear_cache() {
+    for (int i=0; i < MATRIX_ROWS; i++) {
+      for (int j=0; j < MATRIX_COLS; j++) {
+        write_cache(j, i, min_layer_value);
+      }
+    }
+  }
+}
+
+class LayerCache : public testing::Test
+{
+public:
+  LayerCache()
+  {
+    clear_cache();
+  }
+};
+
+TEST_F(LayerCache, LayerCacheIsInitializedToZero) {
+  for (int i=0; i < MATRIX_ROWS; i++) {
+    for (int j=0; j < MATRIX_COLS; j++) {
+      EXPECT_EQ(read_cache(j, i), min_layer_value);
+    }
+  }
+}
+
+TEST_F(LayerCache, FillAndClearCache) {
+  fill_cache();
+  clear_cache();
+  for (int i=0; i < MATRIX_ROWS; i++) {
+    for (int j=0; j < MATRIX_COLS; j++) {
+      EXPECT_EQ(read_cache(j, i), min_layer_value);
+    }
+  }
+}
+
+TEST_F(LayerCache, WriteAndReadFirstPosMaximumValue) {
+  write_cache(0, 0, max_layer_value);
+  EXPECT_EQ(read_cache(0, 0), max_layer_value);
+  // The second position should not be updated
+  EXPECT_EQ(read_cache(1, 0), min_layer_value);
+  EXPECT_EQ(read_cache(0, 1), min_layer_value);
+}
+
+TEST_F(LayerCache, WriteAndReadSecondPosMaximumValue) {
+  write_cache(1, 0, max_layer_value);
+  EXPECT_EQ(read_cache(1, 0), max_layer_value);
+  // The surrounding positions should not be updated
+  EXPECT_EQ(read_cache(0, 0), min_layer_value);
+  EXPECT_EQ(read_cache(0, 1), min_layer_value);
+}
+
+TEST_F(LayerCache, WriteAndReadFirstPosAlternatingBitsStartingWith1) {
+  write_cache(0, 0, alternating_starting_with_1);
+  EXPECT_EQ(read_cache(0, 0), alternating_starting_with_1);
+  // The second position should not be updated
+  EXPECT_EQ(read_cache(1, 0), min_layer_value);
+  EXPECT_EQ(read_cache(0, 1), min_layer_value);
+}
+
+TEST_F(LayerCache, WriteAndReadSecondPosAlternatingBitsStartingWith1) {
+  write_cache(1, 0, alternating_starting_with_1);
+  EXPECT_EQ(read_cache(1, 0), alternating_starting_with_1);
+  // The surrounding positions should not be updated
+  EXPECT_EQ(read_cache(0, 0), min_layer_value);
+  EXPECT_EQ(read_cache(0, 1), min_layer_value);
+}
+
+TEST_F(LayerCache, WriteAndReadFirstPosAlternatingBitsStartingWith0) {
+  write_cache(0, 0, alternating_starting_with_0);
+  EXPECT_EQ(read_cache(0, 0), alternating_starting_with_0);
+  // The second position should not be updated
+  EXPECT_EQ(read_cache(1, 0), min_layer_value);
+  EXPECT_EQ(read_cache(0, 1), min_layer_value);
+}
+
+TEST_F(LayerCache, WriteAndReadSecondPosAlternatingBitsStartingWith0) {
+  write_cache(1, 0, alternating_starting_with_0);
+  EXPECT_EQ(read_cache(1, 0), alternating_starting_with_0);
+  // The surrounding positions should not be updated
+  EXPECT_EQ(read_cache(0, 0), min_layer_value);
+  EXPECT_EQ(read_cache(0, 1), min_layer_value);
+}