syscall: Add naive uprint syscall

1 files changed, 15 insertions, 0 deletions

diff --git a/src/lib/syscall.zig b/src/lib/syscall.zig
index 8f30972..642d0c4 100644
--- a/src/lib/syscall.zig
+++ b/src/lib/syscall.zig
@@ -2,6 +2,8 @@
 //
 // SPDX-License-Identifier: AGPL-3.0-or-later
 
+const instructions = @import("instructions.zig");
+const paging = @import("paging.zig");
 const trap = @import("trap.zig");
 
 pub const Error = error{
@@ -10,6 +12,19 @@ pub const Error = error{
 
 pub fn handle(trap_frame: *const trap.Frame) !void {
     switch (trap_frame.general_purpose_registers[17]) {
+        100000 => uprint(trap_frame),
         else => return Error.UnknownSyscall,
     }
 }
+
+fn uprint(trap_frame: *const trap.Frame) void {
+    const procmem: *paging.Table = @ptrFromInt(instructions.satp.read().ppn << 12);
+
+    const paddr = procmem.translate(trap_frame.general_purpose_registers[10]).?;
+
+    const str_ptr: [*]const u8 = @ptrFromInt(paddr);
+    const str = str_ptr[0..trap_frame.general_purpose_registers[11]];
+
+    const w = @import("Console.zig").autoChoose().?.writer();
+    w.print("User message: {s}\r\n", .{str}) catch unreachable;
+}