From 9160f2912eb57910e45b681b7b5eef9acb6a922e Mon Sep 17 00:00:00 2001
From: Steven Le Rouzic <steven.lerouzic@gmail.com>
Date: Mon, 13 May 2024 12:21:59 +0200
Subject: OS Hello world

---
 os/boot.S | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)
 create mode 100644 os/boot.S

(limited to 'os/boot.S')

diff --git a/os/boot.S b/os/boot.S
new file mode 100644
index 0000000..afb966c
--- /dev/null
+++ b/os/boot.S
@@ -0,0 +1,31 @@
+.option norvc
+
+.section .init
+
+.equ UART_BASE, 0x10000000
+
+.global kstart
+kstart:
+    la        a0, _str
+    call      _println
+
+_halt:
+    wfi
+    j         _halt
+
+_println:
+    li        t0, UART_BASE
+_println_loop:
+    lb        t1, 0(a0)
+    beqz      t1, _end_println_loop
+    sb        t1, 0(t0)
+    addi      a0, a0, 1
+    j         _println_loop
+_end_println_loop:
+    li        t1, '\n'
+    sb        t1, 0(t0)
+    ret
+
+.section .rodata
+
+_str: .string "Hello, world!"
-- 
cgit