From 50cbc7510250a64674d619d13f5912edf08b767d Mon Sep 17 00:00:00 2001
From: Robert Morris <rtm@csail.mit.edu>
Date: Sat, 1 Jun 2019 05:33:38 -0400
Subject: first shell prints $ prompt, though no console input yet

---
 riscv.h | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

(limited to 'riscv.h')

diff --git a/riscv.h b/riscv.h
index 92fa6e3..5e54935 100644
--- a/riscv.h
+++ b/riscv.h
@@ -129,7 +129,7 @@ w_sscratch(uint64 x)
   asm("csrw sscratch, %0" : : "r" (x));
 }
 
-// Supervisor trap cause
+// Supervisor Trap Cause
 static inline uint64
 r_scause()
 {
@@ -138,6 +138,15 @@ r_scause()
   return x;
 }
 
+// Supervisor Trap Value
+static inline uint64
+r_stval()
+{
+  uint64 x;
+  asm("csrr %0, stval" : "=r" (x) );
+  return x;
+}
+
 #define PGSIZE 4096 // bytes per page
 #define PGSHIFT 12  // bits of offset within a page
 
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