functions for working with grids

1 files changed, 81 insertions, 0 deletions

diff --git a/src/grids.c b/src/grids.c
new file mode 100644
index 0000000..10a934e
--- /dev/null
+++ b/src/grids.c
@@ -0,0 +1,81 @@
+#include <stdlib.h>
+#include <string.h>
+#include "grids.h"
+
+/*
+ * Creates a grid for storing the results of the escape algorithm
+ */
+grid_t* create_grid(const size_t x, const size_t y){
+    if(x <= 0 || y <= 0) return NULL;
+
+    const size_t size = x * y;
+    size_t* data = malloc(size * sizeof(size_t));
+    if(!data) return NULL;
+
+    grid_t* grid = malloc(sizeof(grid_t));
+    if(!grid){
+        free(data);
+        return NULL;
+    }
+
+    grid->x = x;
+    grid->y = y;
+    grid->size = size;
+    grid->data = data;
+
+    return grid;
+}
+
+/*
+ * Sets all entries of a grid to the value val
+ */
+void set_grid(grid_t* grid, const double val){
+    if(!grid || !grid->data) return;
+    memset(grid->data, val, grid->size);
+}
+
+/*
+ * Creates a copy of a grid
+ */
+grid_t* copy_grid(const grid_t* grid){
+    if(!grid || !grid->data) return NULL;
+
+    grid_t* grid_copy = create_grid(grid->x, grid->y);
+    if(!grid_copy) return NULL;
+
+    memcpy(grid_copy->data, grid->data, grid->size);
+
+    return grid_copy;
+}
+
+/*
+ * Frees a grid and its members
+ */
+void free_grid(grid_t* grid){
+    if(!grid) return;
+
+    free(grid->data);
+    free(grid);
+}
+
+/*
+ * Checks if two grids are exactly equal
+ * This may return incorrect values due to floating point arrithmetic errors 
+ * that occur while the grid is being filled
+ */
+bool grid_equal(const grid_t* grid1, const grid_t* grid2){
+    return grid1->x == grid2->x && grid1->y == grid2->y &&
+        memcmp(grid1->data, grid2->data, grid1->size) == 0;
+}
+
+/*
+ * Checks if two grids have a given maximum difference
+ */
+bool grid_allclose(const grid_t *grid1, const grid_t *grid2, const size_t max_error){
+    if(grid1->x != grid2->x || grid1->y != grid2->y) return false;
+    const size_t size = grid1->size;
+    for(size_t i = 0; i < size; i++){
+        if(abs(grid1->data[i] - grid2->data[i]) >= max_error) return false;
+    }
+    return true;
+}