From 905c5da7a9bfa44d25fa1a5978efcdb754422c57 Mon Sep 17 00:00:00 2001
From: David Harris <David_Harris@hmc.edu>
Date: Tue, 24 Oct 2023 10:45:41 -0700
Subject: [PATCH] Tested assembly language file for the pause example

---
 .gitignore                |  1 +
 examples/asm/etc/Makefile | 11 +++++++++++
 examples/asm/etc/pause.S  | 25 +++++++++++++++++++++++++
 3 files changed, 37 insertions(+)
 create mode 100644 examples/asm/etc/Makefile
 create mode 100644 examples/asm/etc/pause.S

diff --git a/.gitignore b/.gitignore
index 04ae44109..b4223b50e 100644
--- a/.gitignore
+++ b/.gitignore
@@ -62,6 +62,7 @@ examples/fp/fpcalc/fpcalc
 examples/C/inline/inline
 examples/C/sum_mixed/sum_mixed
 examples/asm/trap/trap
+examples/asm/etc/pause
 src/fma/fma16_testgen
 linux/devicetree/debug/*
 !linux/devicetree/debug/dump-dts.sh
diff --git a/examples/asm/etc/Makefile b/examples/asm/etc/Makefile
new file mode 100644
index 000000000..72f99e975
--- /dev/null
+++ b/examples/asm/etc/Makefile
@@ -0,0 +1,11 @@
+TARGET = pause
+
+$(TARGET).objdump: $(TARGET)
+	riscv64-unknown-elf-objdump -D $(TARGET) > $(TARGET).objdump
+    
+pause: pause.S Makefile
+	riscv64-unknown-elf-gcc -o pause -march=rv32ia_zihintpause -mabi=ilp32 -mcmodel=medany \
+	    -nostartfiles -T../../link/link.ld  pause.S
+
+clean:
+	rm -f $(TARGET) $(TARGET).objdump
diff --git a/examples/asm/etc/pause.S b/examples/asm/etc/pause.S
new file mode 100644
index 000000000..4e0aacfb4
--- /dev/null
+++ b/examples/asm/etc/pause.S
@@ -0,0 +1,25 @@
+.section .text.init
+.globl rvtest_entry_point
+rvtest_entry_point:
+
+
+la a0, lock
+
+spinlock:				# address of lock is in a0
+	lr.w t0, (a0)		# read the lock
+	bnez t0, retry	    # spin until free
+	li   t1, 1          
+	sc.w t0, t1, (a0)	# try to write a 1 to take lock
+	bnez t0, retry	    # spin until successful
+	ret				    # got the lock!
+retry:				    # no lock yet
+	pause				# pause hint to reduce spin power
+	j spinlock			# try again
+
+
+self_loop:
+    j self_loop
+
+.data
+lock:   
+    .word 1
\ No newline at end of file