From 669ee6ca121ef9fc5ab4892a63c5dad254a92c8e Mon Sep 17 00:00:00 2001
From: David Harris <David_Harris@hmc.edu>
Date: Sun, 13 Oct 2024 20:59:41 -0700
Subject: [PATCH] WALLY-init-lib improvements to support functional coverage

---
 tests/coverage/WALLY-init-lib.h | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/tests/coverage/WALLY-init-lib.h b/tests/coverage/WALLY-init-lib.h
index edf867240..b6b4f56b1 100644
--- a/tests/coverage/WALLY-init-lib.h
+++ b/tests/coverage/WALLY-init-lib.h
@@ -127,6 +127,17 @@ write_tohost:
 
 self_loop:
     j self_loop         # wait
+
+// utility routines
+
+# put a 1 in msb of a0 (position XLEN-1); works for both RV32 and RV64
+setmsb:
+    li a0, 0x80000000   # 1 in bit 31
+    slli a1, a0, 1      # check if register is wider than 31 bits
+    beqz a1, 1f         # yes, a0 has 1 in bit 31
+    slli a0, a0, 16     # no: shift a0 to have 1 inn bit 63
+    slli a0, a0, 16     # use two shifts of 16 bits each to be compatible with compiling either RV32 or 64
+    ret                 # return to calller
     
 .section .tohost 
 tohost:                 # write to HTIF
@@ -139,6 +150,9 @@ begin_signature:
     .fill 6*(XLEN/32),4,0xdeadbeef    # 
 end_signature:
 
+scratch:
+    .fill 4,4,0x0
+
 # Initialize stack with room for 512 bytes
 .bss
     .space 512