From 9e76b9001c37ab2da2e99c922406b991bd0e53af Mon Sep 17 00:00:00 2001
From: Flavian Kaufmann <flavian@flaviankaufmann.ch>
Date: Wed, 15 May 2024 08:27:12 +0200
Subject: running c program

---
 prog/src/startup.s | 42 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)
 create mode 100644 prog/src/startup.s

(limited to 'prog/src/startup.s')

diff --git a/prog/src/startup.s b/prog/src/startup.s
new file mode 100644
index 0000000..7adfb5e
--- /dev/null
+++ b/prog/src/startup.s
@@ -0,0 +1,42 @@
+.section .init
+.globl _start
+_start:
+    /* Set up stack pointer */
+    la sp, _stack_end
+
+    /* Initialize .data section (copy from LMA to VMA) */
+    la t0, _sdata       /* VMA start of .data */
+    la t1, _edata       /* VMA end of .data */
+    la t2, _etext       /* LMA start of .data in flash */
+copy_data:
+    beq t0, t1, clear_bss
+    lw t3, 0(t2)
+    sw t3, 0(t0)
+    addi t0, t0, 4
+    addi t2, t2, 4
+    j copy_data
+
+clear_bss:
+    /* Clear .bss section */
+    la t0, _sbss        /* VMA start of .bss */
+    la t1, _ebss        /* VMA end of .bss */
+clear_loop:
+    beq t0, t1, init_libc
+    sw x0, 0(t0)
+    addi t0, t0, 4
+    j clear_loop
+
+init_libc:
+    /* Call libc initialization functions */
+    /* call _init */
+
+    /* Call main function */
+    call main
+
+finalize_libc:
+    /* Call libc finalization functions */
+    /* call _fini */
+
+halt:
+    /* Infinite loop after main returns */
+    j halt
-- 
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