From b7ca7f78c1f2979b54c22ab1dbeecf2b36b7afd9 Mon Sep 17 00:00:00 2001
From: IonutParau <ionut.alex.parau@gmail.com>
Date: Mon, 7 Jul 2025 20:27:29 +0200
Subject: [PATCH] rng

---
 src/neonucleus.h | 17 +++++++++++++++++
 src/utils.c      | 31 +++++++++++++++++++++++++++++++
 2 files changed, 48 insertions(+)

diff --git a/src/neonucleus.h b/src/neonucleus.h
index 3871342..b86483a 100644
--- a/src/neonucleus.h
+++ b/src/neonucleus.h
@@ -128,10 +128,25 @@ typedef struct nn_Clock {
     nn_ClockProc *proc;
 } nn_Clock;
 
+typedef size_t nn_RngProc(void *userdata);
+
+typedef struct nn_Rng {
+    void *userdata;
+    size_t maximum;
+    nn_RngProc *proc;
+} nn_Rng;
+
+size_t nn_rand(nn_Rng *rng);
+// returns from 0 to 1 (inclusive)
+double nn_randf(nn_Rng *rng);
+// returns from 0 to 1 (exclusive)
+double nn_randfe(nn_Rng *rng);
+
 typedef struct nn_Context {
     nn_Alloc allocator;
     nn_LockManager lockManager;
     nn_Clock clock;
+    nn_Rng rng;
 } nn_Context;
 
 // TODO: write a bunch of utils so this *can* work on baremetal.
@@ -140,6 +155,7 @@ typedef struct nn_Context {
 nn_Alloc nn_libcAllocator();
 nn_Clock nn_libcRealTime();
 nn_LockManager nn_libcMutex();
+nn_Rng nn_libcRng();
 nn_Context nn_libcContext();
 #endif
 
@@ -283,6 +299,7 @@ nn_Context *nn_getContext(nn_universe *universe);
 nn_Alloc *nn_getAllocator(nn_universe *universe);
 nn_Clock *nn_getClock(nn_universe *universe);
 nn_LockManager *nn_getLockManager(nn_universe *universe);
+nn_Rng *nn_getRng(nn_universe *universe);
 void nn_unsafeDeleteUniverse(nn_universe *universe);
 void *nn_queryUserdata(nn_universe *universe, const char *name);
 void nn_storeUserdata(nn_universe *universe, const char *name, void *data);
diff --git a/src/utils.c b/src/utils.c
index 0ce582e..a2c4572 100644
--- a/src/utils.c
+++ b/src/utils.c
@@ -61,11 +61,25 @@ nn_Alloc nn_libcAllocator() {
     };
 }
 
+static size_t nni_rand(void *userdata) {
+    return rand();
+}
+
+nn_Rng nn_libcRng() {
+    srand(time(NULL));
+    return (nn_Rng) {
+        .userdata = NULL,
+        .maximum = RAND_MAX,
+        .proc = nni_rand,
+    };
+}
+
 nn_Context nn_libcContext() {
     return (nn_Context) {
         .allocator = nn_libcAllocator(),
         .clock = nn_libcRealTime(),
         .lockManager = nn_libcMutex(),
+        .rng = nn_libcRng(),
     };
 }
 #endif
@@ -89,6 +103,23 @@ void nn_deallocStr(nn_Alloc *alloc, char *s) {
     nn_dealloc(alloc, s, strlen(s)+1);
 }
 
+size_t nn_rand(nn_Rng *rng) {
+    return rng->proc(rng->userdata);
+}
+
+// returns from 0 to 1 (inclusive)
+double nn_randf(nn_Rng *rng) {
+    double x = nn_rand(rng);
+    return x / rng->maximum;
+}
+
+// returns from 0 to 1 (exclusive)
+double nn_randfe(nn_Rng *rng) {
+    double x = nn_rand(rng);
+    if(x >= rng->maximum) return 0;
+    return x / rng->maximum;
+}
+
 #ifndef NN_BAREMETAL
 
 #ifdef NN_POSIX