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-rw-r--r--src/start.s17
1 files changed, 17 insertions, 0 deletions
diff --git a/src/start.s b/src/start.s new file mode 100644 index 0000000..58efed0 --- /dev/null +++ b/src/start.s
@@ -0,0 +1,17 @@
1.section .text
2.globl _start
3.type _start, @function
4_start:
5 xorq %rbp, %rbp # frame ptr (%rbp) = null. marks stack bottom.
6
7 movl (%rsp), %edi # argc = first 4 bytes of stack.
8 leaq 8(%rsp), %rsi # argv = address of first arg ptr.
9
10 call main # see main.c.
11
12 movl %eax, %edi # status = ret val.
13 movl $1, %eax # SYS_exit = 1.
14 syscall
15
16 .size _start, .-_start
17 hlt # if syscall fails hang.