1 files changed, 40 insertions, 0 deletions
diff --git a/src/boot/crt0.S b/src/boot/crt0.S
new file mode 100644
index 0000000..7935a6e
--- /dev/null
+++ b/src/boot/crt0.S
@@ -0,0 +1,40 @@
+	.section .crt0, "ax"
+
+// Load data segment to SRAM
+	ldr r0, =__data_src__
+	ldr r1, =__data_dst__
+	ldr r2, =__data_size__
+	mov r3, #0
+data_seg_start:
+	cmp r2, #0
+	beq data_seg_end
+	ldrb r3, [r0]
+	strb r3, [r1]
+	add r0, #1
+	add r1, #1
+	sub r2, #1
+	b data_seg_start
+data_seg_end:
+
+// Init bss in SRAM
+	ldr r0, =__bss_start__
+	ldr r1, =__bss_size__
+	mov r2, #0
+bss_init_start:
+	cmp r1, #0
+	beq bss_init_end
+	strb r2, [r0]
+	add r0, #1
+	sub r1, #1
+	b bss_init_start
+bss_init_end:
+
+	// Setup stack
+	ldr r0, =SRAM_END
+	mov sp, r0
+
+	// Start kernel
+	ldr r0, =main
+	blx r0
+
+	.set SRAM_END, 0x20042000