Add BPF Rust noop example (#316)

web3.js/examples/bpf-rust-noop/src/lib.rs

@@ -0,0 +1,55 @@
+//! @brief Example Rust-based BPF program that prints out the parameters passed to it
+
+#![cfg(not(test))]
+#![no_std]
+
+mod solana_sdk;
+
+use solana_sdk::*;
+
+struct SStruct {
+    x: u64,
+    y: u64,
+    z: u64,
+}
+
+#[inline(never)]
+fn return_sstruct() -> SStruct {
+    SStruct { x: 1, y: 2, z: 3 }
+}
+
+fn process(ka: &mut [SolKeyedAccount], data: &[u8], info: &SolClusterInfo) -> bool {
+    sol_log("Tick height:");
+    sol_log_64(info.tick_height, 0, 0, 0, 0);
+    sol_log("Program identifier:");
+    sol_log_key(&info.program_id);
+
+    // Log the provided account keys and instruction input data.  In the case of
+    // the no-op program, no account keys or input data are expected but real
+    // programs will have specific requirements so they can do their work.
+    sol_log("Account keys and instruction input data:");
+    sol_log_params(ka, data);
+
+    {
+        // Test - use core methods, unwrap
+
+        // valid bytes, in a stack-allocated array
+        let sparkle_heart = [240, 159, 146, 150];
+
+        let result_str = core::str::from_utf8(&sparkle_heart).unwrap();
+
+        sol_log_64(0, 0, 0, 0, result_str.len() as u64);
+        sol_log(result_str);
+        assert_eq!("💖", result_str);
+    }
+
+    {
+        // Test - struct return
+        let s = return_sstruct();
+        sol_log_64(0, 0, s.x, s.y, s.z);
+        assert_eq!(s.x + s.y + s.z, 6);
+    }
+
+    sol_log("Success");
+    true
+}