sysexchange: Handle invalid and user-provided Status codes

Fixes #52.

1 files changed, 17 insertions, 0 deletions

diff --git a/src/lib/sysexchange.zig b/src/lib/sysexchange.zig
index d6405b9..b8cd62d 100644
--- a/src/lib/sysexchange.zig
+++ b/src/lib/sysexchange.zig
@@ -6,6 +6,10 @@ const std = @import("std");
 
 const trap = @import("trap.zig");
 
+pub const UserError = error{
+    UserError,
+};
+
 pub const Status = enum(usize) {
     success = 0,
     hart_id_out_of_range,
@@ -70,7 +74,12 @@ pub const Status = enum(usize) {
     is_a_container,
     provide_not_supported,
     remove_not_supported,
+    user_error = user_range_start,
     unknown = std.math.maxInt(usize),
+    _,
+
+    pub const user_range_start = 0xffff0000_00000000;
+    pub const user_range_end = 0xffffffff_00000000;
 
     pub fn fromError(err: anyerror) Status {
         return switch (err) {
@@ -136,6 +145,7 @@ pub const Status = enum(usize) {
             error.IsAContainer => .is_a_container,
             error.ProvideNotSupported => .provide_not_supported,
             error.RemoveNotSupported => .remove_not_supported,
+            error.UserError => .user_error,
             else => .unknown,
         };
     }
@@ -207,9 +217,16 @@ pub const Status = enum(usize) {
             .is_a_container => error.IsAContainer,
             .provide_not_supported => error.ProvideNotSupported,
             .remove_not_supported => error.RemoveNotSupported,
+            .user_error => error.UserError,
             .unknown => error.Unknown,
+            _ => if (self.isUserError()) error.UserError else error.Unknown,
         };
     }
+
+    pub inline fn isUserError(self: Status) bool {
+        const status = @intFromEnum(self);
+        return status > user_range_start and status < user_range_end;
+    }
 };
 
 pub fn Result(comptime T: type) type {