Refactor/RNG system (#476)

* Extract rng manipulation to its own file * clang format * Get CPU cycles since game start to use for RNG * change a few things * clang format * Implement suggestions from @ricfehr3 * clang format * Fix rebase issue * clang format * Create RngInfo struct to hold seed and step * clang format * Make a note about rng_restore system not having been tested properly yet * Apply suggestions from @ricfehr3 Co-authored-by: Rickey <ric@rf3.xyz> * clang format --------- Co-authored-by: MathisMartin31 <mathis.martin31@gmail.com> Co-authored-by: Rickey <ric@rf3.xyz>
2026-05-21 19:47:48 -07:00
parent e3f680d6d0
commit c2844a5d32
14 changed files with 162 additions and 57 deletions
@@ -0,0 +1,50 @@
+#include "random.h"
+
+#include "game_variables.h"
+
+#include <stdlib.h>
+#include <tonc.h>
+
+// Accumulate timer 1 into a bigger variable so we can generate more diverse seeds
+static u32 timer_acc = 0;
+
+// Timers usage docs: https://gbadev.net/tonc/timers.html
+void rng_init(void)
+{
+    REG_TM1D = 0;
+    REG_TM1CNT = TM_FREQ_1 | TM_ENABLE; // using timer with x1 prescale
+}
+
+void rng_update(void)
+{
+    timer_acc += (u32)REG_TM1D;
+}
+
+void rng_set_seed(u32 seed)
+{
+    g_game_vars.rng_info.seed = seed % (MAX_SEED + 1);
+    g_game_vars.rng_info.step = 0;
+    srand(g_game_vars.rng_info.seed);
+}
+
+void rng_shuffle_seed(void)
+{
+    rng_set_seed(timer_acc);
+}
+
+u32 rng_get_u32(void)
+{
+    g_game_vars.rng_info.step++;
+    return rand();
+}
+
+void rng_restore(RngInfo info)
+{
+    g_game_vars.rng_info = info;
+
+    srand(g_game_vars.rng_info.seed);
+    for (u32 i = 0; i < g_game_vars.rng_info.step; i++)
+    {
+        (void)rng_get_u32();
+    }
+}