Rewrite planemap and idalloc in pure C++

luprex/syscpp/util.cpp

@@ -58,4 +58,45 @@ const stringvec trim_and_uncomment(const stringvec &lines) {
     return result;
 }
 
+double distance_squared(double x1, double y1, double x2, double y2) {
+    double dx = x1 - x2;
+    double dy = y1 - y2;
+    return dx*dx + dy*dy;
+}
+
+// These are Bob Jenkins' Lookup3.
+
+#define hash_rot(x,k) (((x)<<(k)) | ((x)>>(32-(k))))
+
+#define hash_mix(a,b,c) { \
+    a -= c; a ^= hash_rot(c, 4); c += b; \
+    b -= a; b ^= hash_rot(a, 6); a += c; \
+    c -= b; c ^= hash_rot(b, 8); b += a; \
+    a -= c; a ^= hash_rot(c,16); c += b; \
+    b -= a; b ^= hash_rot(a,19); a += c; \
+    c -= b; c ^= hash_rot(b, 4); b += a; \
+}
+
+#define hash_final(a,b,c) { \
+    c ^= b; c -= hash_rot(b,14); \
+    a ^= c; a -= hash_rot(c,11); \
+    b ^= a; b -= hash_rot(a,25); \
+    c ^= b; c -= hash_rot(b,16); \
+    a ^= c; a -= hash_rot(c,4);  \
+    b ^= a; b -= hash_rot(a,14); \
+    c ^= b; c -= hash_rot(b,24); \
+}
+
+uint32_t hash3(uint32_t a, uint32_t b, uint32_t c) {
+    hash_final(a, b, c);
+    return c;
+}
+
+double hash_to_float(double lo, double hi, uint32_t a, uint32_t b, uint32_t c) {
+    double result = hash3(a, b, c); // Lossless.
+    result *= ((hi-lo) * (1.0 / 0xFFFFFFFF));
+    result += lo;
+    return result;
+}
+
 } // namespace util