From 66ca916805efee6b35b8dd6104fb1da50dd1dc8b Mon Sep 17 00:00:00 2001
From: Andrew Kelley <superjoe30@gmail.com>
Date: Tue, 15 Dec 2015 00:07:51 -0700
Subject: [PATCH] std: expose exit syscall

---
 example/expressions/expressions.zig | 14 +++++---------
 std/std.zig                         | 19 +++++++++++++++++++
 2 files changed, 24 insertions(+), 9 deletions(-)

diff --git a/example/expressions/expressions.zig b/example/expressions/expressions.zig
index cab306c46676ec3e65dc28cc053f6b2dd8894c9d..4a1090939a0e64d49daec813eb8e0a03222948bb 100644
--- a/example/expressions/expressions.zig
+++ b/example/expressions/expressions.zig
@@ -1,10 +1,6 @@
 export executable "expressions";
 
-#link("c")
-extern {
-    fn puts(s: &const u8) -> i32;
-    fn exit(code: i32) -> unreachable;
-}
+use "std.zig";
 
 fn other_exit() -> unreachable {
     if (true) { exit(0); }
@@ -12,21 +8,21 @@ fn other_exit() -> unreachable {
     unreachable;
 }
 
-export fn _start() -> unreachable {
+export fn main(argc: isize, argv: &&u8, env: &&u8) -> unreachable {
     const a : i32 = 1;
     const b = 2 as i32;
     // const c : i32; // not yet support for const variables
     // const d; // parse error
     if (a + b == 3) {
         const no_conflict : i32 = 5;
-        if (no_conflict == 5) { puts(c"OK 1"); }
+        if (no_conflict == 5) { print_str("OK 1\n" as string); }
     }
 
     const c = {
         const no_conflict : i32 = 10;
         no_conflict
     };
-    if (c == 10) { puts(c"OK 2"); }
+    if (c == 10) { print_str("OK 2\n" as string); }
 
     void_fun(1, void, 2);
 
@@ -49,7 +45,7 @@ loop_start:
     if i == 3 {
         goto done;
     }
-    puts(c"loop");
+    print_str("loop\n" as string);
     i = i + 1;
     goto loop_start;
 done:
diff --git a/std/std.zig b/std/std.zig
index 8b1962844186cd9ce6fa02894cce9f610ce2e6af..ea3b0d20f67e8854c9b149b26e5ea0105d8dddc4 100644
--- a/std/std.zig
+++ b/std/std.zig
@@ -1,6 +1,20 @@
 const SYS_write : isize = 1;
+const SYS_exit : isize = 60;
 const stdout_fileno : isize = 1;
 
+fn syscall1(number: isize, arg1: isize) -> isize {
+    var result : isize;
+    asm volatile ("
+        mov %[number], %%rax
+        mov %[arg1], %%rdi
+        syscall
+        mov %%rax, %[ret]"
+        : [ret] "=m" (result)
+        : [number] "r" (number), [arg1] "r" (arg1)
+        : "rcx", "r11", "rax", "rdi");
+    return result;
+}
+
 fn syscall3(number: isize, arg1: isize, arg2: isize, arg3: isize) -> isize {
     var result : isize;
     asm volatile ("
@@ -20,6 +34,11 @@ pub fn write(fd: isize, buf: &const u8, count: usize) -> isize {
     return syscall3(SYS_write, fd, buf as isize, count as isize);
 }
 
+pub fn exit(status: i32) -> unreachable {
+    syscall1(SYS_exit, status as isize);
+    unreachable;
+}
+
 // TODO error handling
 // TODO handle buffering and flushing
 pub fn print_str(str : string) -> isize {
-- 
2.54.0