Add option to set random seed for deterministic behavior

Bump version to 1.6

lib/CMakeLists.txt

@@ -15,6 +15,7 @@ find_package(PkgConfig REQUIRED)
 pkg_search_module(PNG REQUIRED libpng)
 
 check_symbol_exists(arc4random_uniform "stdlib.h" HAVE_ARC4RANDOM)
+check_symbol_exists(srand_deterministic "stdlib.h" HAVE_SRAND_DETERMINISTIC)
 
 configure_file ("${CMAKE_CURRENT_SOURCE_DIR}/config.h.in"
                 "${CMAKE_CURRENT_SOURCE_DIR}/config.h" )

lib/config.h.in

@@ -1 +1,2 @@
 #cmakedefine HAVE_ARC4RANDOM @HAVE_ARC4RANDOM@
+#cmakedefine HAVE_SRAND_DETERMINISTIC @HAVE_SRAND_DETERMINISTIC@

lib/grid.c

@@ -1,5 +1,6 @@
 #include <stdlib.h>
 #include "grid.h"
+#include "options.h"
 #include "config.h"
 
 #define MAX_EDGE_WEIGHT 100
@@ -19,14 +20,25 @@
 #define HORIZONTAL_HALF_LEFT "\xe2\x95\xb8"
 #define HORIZONTAL_HALF_RIGHT "\xe2\x95\xba"
 
-static edgeweight_t random_edgeweight() {
+static edgeweight_t random_edgeweight(mazeoptions_t const* options) {
+    if (!options->seed_set) {
 #ifdef HAVE_ARC4RANDOM
-    return arc4random_uniform(MAX_EDGE_WEIGHT);
+        return arc4random_uniform(MAX_EDGE_WEIGHT);
 #else // HAVE_ARC4RANDOM
-    return random()%MAX_EDGE_WEIGHT;
+        return random()%MAX_EDGE_WEIGHT;
 #endif // HAVE_ARC4RANDOM
+    } else {
+        // use deterministic random number generator
+        return rand()%MAX_EDGE_WEIGHT;
+    }
 }
 
+#ifdef HAVE_SRAND_DETERMINISTIC
+#define SRAND(x) (srand_deterministic(x))
+#else
+#define SRAND(x) (srand(x))
+#endif // defined(HAVE_SRAND_DETERMINISTIC)
+
 mazegrid_t mazegrid_new(size_t width, size_t height) {
     mazeedges_t** grid = calloc(height, sizeof(mazeedges_t*));
     for (size_t i = 0; i < height; i++) {
@@ -72,11 +84,16 @@ edgeweight_t mazegrid_get_edge(mazegrid_t const* g, size_t x, size_t y, mazeedge
     else return g->grid[y][x].up;
 }
 
-void mazegrid_randomize(mazegrid_t* g) {
+void mazegrid_randomize(mazegrid_t* g, mazeoptions_t const* options) {
+    // initialize random system
+    if (options->seed_set) {
+        SRAND(options->seed);
+    }
+
     for (size_t i = 0; i < g->height; i++) {
         for (size_t j = 0; j < g->width; j++) {
-            if (i < g->height - 1) g->grid[i][j].up = random_edgeweight();
-            if (j < g->width - 1) g->grid[i][j].right = random_edgeweight();
+            if (i < g->height - 1) g->grid[i][j].up = random_edgeweight(options);
+            if (j < g->width - 1) g->grid[i][j].right = random_edgeweight(options);
         }
     }
 }

lib/grid.h

@@ -10,7 +10,7 @@ void mazegrid_free(mazegrid_t* g);
 int mazegrid_set_edge(mazegrid_t* g, size_t x, size_t y, mazeedge_dir_t dir, edgeweight_t wt);
 edgeweight_t mazegrid_get_edge(mazegrid_t const* g, size_t, size_t y, mazeedge_dir_t dir);
 
-void mazegrid_randomize(mazegrid_t* g);
+void mazegrid_randomize(mazegrid_t* g, mazeoptions_t const* options);
 void mazegrid_uniform(mazegrid_t* g);
 
 void mazegrid_print(mazegrid_t const* g, FILE * f);

lib/maze.c

@@ -1,13 +1,21 @@
 #include <mazemaker.h>
+#include <stdlib.h>
 #include "grid.h"
 #include "prim.h"
 
-void mazemaker_generate_maze(int width, int height, mazegrid_t* result) {
+void mazemaker_generate_maze_opt(int width, int height, mazegrid_t* result, mazeoptions_t const* options) {
     mazegrid_t g = mazegrid_new(width, height);
-    mazegrid_randomize(&g);
+    mazegrid_randomize(&g, options);
     prim(&g, result);
     mazegrid_free(&g);
 }
+
+void mazemaker_generate_maze(int width, int height, mazegrid_t* result) {
+    mazeoptions_t* options = mazemaker_options_new(); // use defaults
+    mazemaker_generate_maze_opt(width, height, result, options);
+    mazemaker_options_free(options);
+}
+
 void mazemaker_free_maze(mazegrid_t* maze) {
     mazegrid_free(maze);
 }

lib/options.c

@@ -10,6 +10,8 @@ mazeoptions_t* mazemaker_options_new() {
     // set defaults
     memset(result->wall_color, 0, 3);
     memset(result->background_color, 0xff, 3);
+    result->seed = 0;
+    result->seed_set = false;
 
     return result;
 }
@@ -78,3 +80,7 @@ int mazemaker_options_set_background_color(mazeoptions_t* options, char const* c
     return stringToColor(color_desc, options->background_color);
 }
 
+void mazemaker_options_set_seed(mazeoptions_t* options, rand_seed_t seed) {
+    options->seed = seed;
+    options->seed_set = true;
+}

lib/options.h

@@ -2,12 +2,16 @@
 #define _OPTIONS_H 1
 
 #include <stdint.h>
+#include <stdbool.h>
 
 typedef uint8_t rgb_color_t[3];
+typedef unsigned int rand_seed_t;
 
 typedef struct mazeoptions {
     rgb_color_t wall_color;
     rgb_color_t background_color;
+    rand_seed_t seed;
+    bool seed_set;
 } mazeoptions_t;
 
 #endif // !def(_OPTIONS_H)