things!

2026-09-11 02:21:21 +03:00
parent 2e890fb5b7
commit adfae10938
17 changed files with 949 additions and 119 deletions
@@ -0,0 +1,38 @@
+/*
+    Doom-inspired Q15.16 format used for most of everything.
+    https://hackmd.io/9uRB9YbTSBW4Qz_2b8TyDw#Examples-2-DOOM
+*/
+
+#ifndef COM_FIXED_H
+#define COM_FIXED_H
+
+#include <stdint.h>
+
+#define COM_FIXED_FRACBITS 16
+#define COM_FIXED_FRACUNIT (1 << COM_FIXED_FRACBITS)
+
+typedef int32_t com_fixed_t;
+
+static inline com_fixed_t com_fixed_add(com_fixed_t a, com_fixed_t b) {
+  return a + b;
+}
+
+static inline com_fixed_t com_fixed_sub(com_fixed_t a, com_fixed_t b) {
+  return a - b;
+}
+
+static inline com_fixed_t com_fixed_mul(com_fixed_t a, com_fixed_t b) {
+  return (com_fixed_t)(((int64_t)a * (int64_t)b) >> COM_FIXED_FRACBITS);
+}
+
+/* Note: this does not clamp for over/underflow cases */
+static inline com_fixed_t com_fixed_div(com_fixed_t a, com_fixed_t b) {
+  return (com_fixed_t)(((int64_t)a << COM_FIXED_FRACBITS) / (int64_t)b);
+}
+
+/* Approximate square root using Newton-Raphson in 2 iterations over small LUT*/
+com_fixed_t com_fixed_sqrt(com_fixed_t a);
+
+void com_fixed_print(com_fixed_t a);
+
+#endif