fix memory issues and add basic device discovery

discuss: pci/dtb device discovery? now that the x0 issue is fixed it is
entirely possible.

1 files changed, 19 insertions, 1 deletions

diff --git a/src/main.rs b/src/main.rs
index 20dde55..bb1d735 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -5,10 +5,12 @@ pub mod state;
 use crate::core::*;
 use crate::mem::Memory;
 use crate::state::CpuState;
+use std::io::Write;
 
 const MEMORY_SIZE: usize = 64 * 1024 * 1024;
 const REGISTER_NAME_WIDTH: u32 = 0b11111;
 const RO_TARGET: u32 = 0x80000000;
+const WDT_LOCATION: u32 = 0x90000000;
 const UART_ADDR: u32 = 0x10000000;
 
 fn main() {
@@ -23,9 +25,23 @@ fn main() {
         .memory
         .write_multiple_bytes(RO_TARGET as usize, f_dat.as_slice(), 99)
         .unwrap();
+    state
+        .memory
+        .write_multiple_bytes(WDT_LOCATION as usize, &[
+            65, 65, 103, 103, //0x67674141
+            1, 0, 0, 0, // 1 (n_devices)
+            0, 0, 0, 0, // 0 (device type, free RAM)
+            0, 0, 0, 0, // 0 (free RAM, no driver)
+            0, 0, 0, 16, // 0x10000000 (start addr)
+            0, 0, 0, 3 // 48 MB (size)
+        ], 99)
+        .unwrap();
+
     state.memory.write(UART_ADDR as usize, 99, 0).unwrap();
     state.pc = RO_TARGET;
 
+    state.registers[10] = WDT_LOCATION;
+
     loop {
         {
             handle_instruction(&mut state);
@@ -36,6 +52,9 @@ fn main() {
                 print!("{}", uart_byte as char);
             }
             state.memory.write(UART_ADDR as usize, 99, 0).unwrap();
+            std::io::stdout().flush().unwrap();
+
+            state.registers[0] = 0;
         }
     }
 }
@@ -221,7 +240,6 @@ fn handle_instruction(state: &mut CpuState) {
 
                 _ => panic!("Illegal instruction: {:x}", word),
             }
-
         } // ecall (ebreak not implemented)
         0b0101111 => {
             let f5 = word >> 27;