//! system/services/shm-client — the creating half of the shm test (docs/display-v2.md V2).
//! It `shm_create`s a shared region, writes a known pattern into it, and hands the region's
//! capability to `shm-server` as an `ipc_call` send_cap. The server maps that capability and
//! confirms the pattern is visible — proving cross-process shared memory over the extended
//! capability-passing path.

const runtime = @import("runtime");
const system = runtime.system;
const shm = runtime.shm;
const ipc = runtime.ipc;

const pattern_len = 4096;

/// The pattern the server checks — must match shm-server.zig.
fn expected(i: usize) u8 {
    return @truncate(i *% 7 +% 3);
}

fn lookupServer() ?ipc.Handle {
    var attempts: usize = 0;
    while (attempts < 100) : (attempts += 1) {
        if (ipc.lookup(.shm_test)) |h| return h;
        system.sleep(50);
    }
    return null;
}

pub fn main() void {
    const region = shm.create(pattern_len) orelse {
        _ = system.write("shm: create failed\n");
        return;
    };
    var i: usize = 0;
    while (i < pattern_len) : (i += 1) region.ptr[i] = expected(i);

    const server = lookupServer() orelse {
        _ = system.write("shm: no server\n");
        return;
    };
    // A non-empty message (so it reaches on_message, not the ping path), carrying the shm
    // region's capability. The reply is empty; we just need the round trip.
    var reply: [64]u8 = undefined;
    _ = ipc.callCap(server, "shm", &reply, region.handle) catch {
        _ = system.write("shm: call failed\n");
    };
}

pub const panic = runtime.panic;
comptime {
    _ = &runtime.start._start;
}