root: Automatically cast syscall arguments depending on their type

1 files changed, 12 insertions, 2 deletions

diff --git a/src/root.zig b/src/root.zig
index 2e6ab5d..d4d2011 100644
--- a/src/root.zig
+++ b/src/root.zig
@@ -14,11 +14,21 @@ const Result = struct {
 
 const SyscallError = error{Kernel};
 
+fn autoCast(value: anytype) usize {
+    return switch (@typeInfo(@TypeOf(value))) {
+        .Type => @compileError("cannot pass type to system call"),
+        .Void => @compileError("cannot pass void to system call"),
+        .NoReturn => @compileError("cannot pass noreturn to system call"),
+        .Pointer => @intFromPtr(value),
+        else => value,
+    };
+}
+
 fn ecall(number: usize, args: anytype) Result {
     comptime var registers = [_]usize{0} ** max_args;
     inline for (args, 0..) |arg, i| {
-        if (i >= max_args) @compileError("Too many arguments to system call");
-        registers[i] = @bitCast(arg);
+        if (i >= max_args) @compileError("too many arguments to system call");
+        registers[i] = autoCast(arg);
     }
 
     var result: Result = undefined;