From 9066e62a97cc4950a025c6d5caf5597c184b1422 Mon Sep 17 00:00:00 2001
From: Bananymous <oskari.alaranta@bananymous.com>
Date: Wed, 2 Apr 2025 02:44:31 +0300
Subject: [PATCH] Kernel/LibC: Implement sched_yield

---
 kernel/include/kernel/Process.h                | 1 +
 kernel/kernel/Process.cpp                      | 6 ++++++
 userspace/libraries/LibC/CMakeLists.txt        | 1 +
 userspace/libraries/LibC/include/sys/syscall.h | 1 +
 userspace/libraries/LibC/sched.cpp             | 8 ++++++++
 5 files changed, 17 insertions(+)
 create mode 100644 userspace/libraries/LibC/sched.cpp

diff --git a/kernel/include/kernel/Process.h b/kernel/include/kernel/Process.h
index 0f68822b..1b23a290 100644
--- a/kernel/include/kernel/Process.h
+++ b/kernel/include/kernel/Process.h
@@ -182,6 +182,7 @@ namespace Kernel
 		BAN::ErrorOr<long> sys_sigpending(sigset_t* set);
 		BAN::ErrorOr<long> sys_sigprocmask(int how, const sigset_t* set, sigset_t* oset);
 
+		BAN::ErrorOr<long> sys_yield();
 		BAN::ErrorOr<long> sys_pthread_create(const pthread_attr_t* __restrict attr, void (*entry)(void*), void* arg);
 		BAN::ErrorOr<long> sys_pthread_exit(void* value);
 		BAN::ErrorOr<long> sys_pthread_self();
diff --git a/kernel/kernel/Process.cpp b/kernel/kernel/Process.cpp
index 06f7d247..4f9b1507 100644
--- a/kernel/kernel/Process.cpp
+++ b/kernel/kernel/Process.cpp
@@ -2084,6 +2084,12 @@ namespace Kernel
 		return 0;
 	}
 
+	BAN::ErrorOr<long> Process::sys_yield()
+	{
+		Processor::yield();
+		return 0;
+	}
+
 	BAN::ErrorOr<long> Process::sys_pthread_create(const pthread_attr_t* __restrict attr, void (*entry)(void*), void* arg)
 	{
 		if (attr != nullptr)
diff --git a/userspace/libraries/LibC/CMakeLists.txt b/userspace/libraries/LibC/CMakeLists.txt
index abb54937..2ad05ad6 100644
--- a/userspace/libraries/LibC/CMakeLists.txt
+++ b/userspace/libraries/LibC/CMakeLists.txt
@@ -20,6 +20,7 @@ set(LIBC_SOURCES
 	pthread.cpp
 	pwd.cpp
 	scanf_impl.cpp
+	sched.cpp
 	setjmp.cpp
 	signal.cpp
 	stdio.cpp
diff --git a/userspace/libraries/LibC/include/sys/syscall.h b/userspace/libraries/LibC/include/sys/syscall.h
index b6434a97..32de461b 100644
--- a/userspace/libraries/LibC/include/sys/syscall.h
+++ b/userspace/libraries/LibC/include/sys/syscall.h
@@ -90,6 +90,7 @@ __BEGIN_DECLS
 	O(SYS_FSYNC,			fsync)			\
 	O(SYS_SYMLINKAT,		symlinkat)		\
 	O(SYS_HARDLINKAT,		hardlinkat)		\
+	O(SYS_YIELD,			yield)			\
 	O(SYS_PTHREAD_CREATE,	pthread_create)	\
 	O(SYS_PTHREAD_EXIT,		pthread_exit)	\
 	O(SYS_PTHREAD_SELF,		pthread_self)	\
diff --git a/userspace/libraries/LibC/sched.cpp b/userspace/libraries/LibC/sched.cpp
new file mode 100644
index 00000000..72138299
--- /dev/null
+++ b/userspace/libraries/LibC/sched.cpp
@@ -0,0 +1,8 @@
+#include <sched.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+
+int sched_yield(void)
+{
+	return syscall(SYS_YIELD);
+}