1 files changed, 86 insertions, 0 deletions
diff --git a/src/utils/misc.c b/src/utils/misc.c
new file mode 100644
index 0000000..0f3d218
--- /dev/null
+++ b/src/utils/misc.c
@@ -0,0 +1,86 @@
+#include <stdint.h>
+#include <stdlib.h>
+
+#include <string.h>
+
+#include <engine/logging.h>
+#include <engine/utils.h>
+
+/* These should all be in some external facing module "tools" */
+
+f32 lerp(f32 dt, f32 a, f32 b) { return (a * (1.0f - dt)) + (b * dt); }
+
+i32 int_lerp(f32 dt, i32 a, i32 b) {
+  return ((f32)a * (1.0f - dt)) + ((f32)b * dt);
+}
+
+u32 hash(char* str) {
+  u32 sum = 0;
+  while (*str != '\0') {
+    sum ^= (*str) * 0xdeece66d + 0xb;
+    str++;
+  }
+  return sum;
+}
+
+/* Populates dstmap
+ * on success: return pointer to dstmap
+ * on failure: return NULL */
+i32* kernmap(const void* map, i32* dstmap, const v2_i32 mapsize,
+             predicate_t* predicate) {
+  const i32 w = mapsize.x;
+  const i32 h = mapsize.y;
+  i32 mask[w * h];
+
+  if (w * h < 1) return NULL;
+
+  for (i32 i = 0; i < w * h; i++) {
+    mask[i] = predicate((void*)((u64)map + sizeof(i32) * i)) ? 1 : 0;
+  }
+
+  for (i32 y = 1; y < h - 1; y++) {
+    for (i32 x = 1; x < w - 1; x++) {
+      const i32 global_idx = (y * w) + x;
+      const i32 offs = global_idx - w - 1;
+      i32 _sum = 0;
+
+      i32 shift = 0;
+
+      /* We go in the following order */
+      /* ....|0|1|2|....*/
+      /* ....|3|4|5|....*/
+      /* ....|6|7|8|....*/
+      /* Where `4` is in the center, MASK_C */
+      for (i32 yy = offs; yy <= offs + w + w; yy += w) {
+        for (i32 xx = yy; xx < yy + 3; xx++) {
+          _sum = _sum | (mask[xx] << shift++);
+        }
+      }
+
+      dstmap[global_idx] = _sum;
+    }
+  }
+  return dstmap;
+}
+
+/* Returns an index from the given weights. */
+i32 pick_from_sample(const i32* weights, i32 len) {
+  if (len <= 0) return 0;
+
+  /* Cumulative sum */
+  i32 cumweights[len];
+  i32 sum = 0;
+  for (i32 i = 0; i < len; i++) {
+    sum += weights[i];
+    cumweights[i] = sum;
+  }
+
+  if (sum == 0) return 0;
+
+  i32 pick = rand() % sum;
+
+  for (i32 i = 0; i < len; i++) {
+    if (pick < cumweights[i]) return i;
+  }
+  return -1;
+}