3 files changed, 80 insertions, 0 deletions
diff --git a/system/libraries/sys/start.zig b/system/libraries/sys/start.zig
new file mode 100644
index 0000000..a65eec8
--- /dev/null
+++ b/system/libraries/sys/start.zig
@@ -0,0 +1,16 @@
+//! Entry point
+
+extern fn main(pc: u32, pv: [*]const [*:0]const u8) u8;
+
+export fn _start() callconv(.naked) noreturn {
+    asm volatile (
+        \\mov (%%rsp), %%edi
+        \\mov 8(%%rsp), %%rsi
+        \\and $-16, %%rsp
+        \\call main
+        \\movzbl %%al, %%edi
+        \\mov $0x01, %%eax
+        \\syscall
+        \\ud2
+    );
+}
diff --git a/system/libraries/sys/sys.zig b/system/libraries/sys/sys.zig
new file mode 100644
index 0000000..d37e4c8
--- /dev/null
+++ b/system/libraries/sys/sys.zig
@@ -0,0 +1,58 @@
+//! System runtime
+
+pub const start = @import("start.zig");
+
+comptime {
+    _ = start;
+}
+
+pub const Invocation = enum(u64) {
+    exit = 0x01,
+    attach = 0x02,
+    seal = 0x03,
+    view = 0x04,
+    mark = 0x05,
+    spawn = 0x06,
+    wait = 0x07,
+    yield = 0x08,
+    getkeychar = 0x09,
+    viewstack = 0x0A,
+    getlocation = 0x0B,
+    setlocation = 0x0C,
+    postman = 0x0D,
+    wipe = 0x0E,
+};
+
+pub inline fn syscall(invocation: Invocation, args: anytype) u64 {
+    const Args = @TypeOf(args);
+    const fields = @typeInfo(Args).@"struct".fields;
+
+    const arg0: u64 = if (fields.len > 0) toU64(args[0]) else 0;
+    const arg1: u64 = if (fields.len > 1) toU64(args[1]) else 0;
+    const arg2: u64 = if (fields.len > 2) toU64(args[2]) else 0;
+    const arg3: u64 = if (fields.len > 3) toU64(args[3]) else 0;
+    const arg4: u64 = if (fields.len > 4) toU64(args[4]) else 0;
+    const arg5: u64 = if (fields.len > 5) toU64(args[5]) else 0;
+
+    return asm volatile ("syscall"
+        : [ret] "={rax}" (-> u64),
+        : [number] "{rax}" (@intFromEnum(invocation)),
+          [arg0] "{rdi}" (arg0),
+          [arg1] "{rsi}" (arg1),
+          [arg2] "{rdx}" (arg2),
+          [arg3] "{r10}" (arg3),
+          [arg4] "{r8}" (arg4),
+          [arg5] "{r9}" (arg5),
+        : .{ .rcx = true, .r11 = true, .memory = true }
+    );
+}
+
+inline fn toU64(value: anytype) u64 {
+    const T = @TypeOf(value);
+    return switch (@typeInfo(T)) {
+        .int, .comptime_int => @intCast(value),
+        .pointer => @intFromPtr(value),
+        .@"enum" => @intFromEnum(value),
+        else => @bitCast(value),
+    };
+}
diff --git a/system/libraries/sys/sys.zon b/system/libraries/sys/sys.zon
new file mode 100644
index 0000000..35d065e
--- /dev/null
+++ b/system/libraries/sys/sys.zon
@@ -0,0 +1,6 @@
+.{
+    .name = "sys",
+    .version = "1.0.0",
+    .type = .library,
+    .entry = "sys.zig",
+}