Started making debug testcase

tests/custom/debug/Makefile

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+# SPDX-License-Identifier: Apache-2.0 WITH SHL-2.1
+
+TARGET = debug
+
+%.elf.memfile: %.elf %.elf.objdump.adr
+	riscv64-unknown-elf-elf2hex --bit-width $(if $(findstring rv64,$*),64,32) --input $< --output $@
+
+%.elf.objdump.addr: %.elf.objdump
+	extractFunctionRadix.sh $<
+
+$(TARGET).objdump: $(TARGET).elf
+	riscv64-unknown-elf-objdump -D $(TARGET).elf > $(TARGET).objdump
+    
+$(TARGET): $(TARGET).S Makefile
+	riscv64-unknown-elf-gcc -g -o $(TARGET).elf -march=rv64gc -mabi=lp64 -mcmodel=medany \
+	    -nostartfiles -T../../link/link.ld $(TARGET).S 
+
+sim:
+	spike +signature=$(TARGET).signature.output +signature-granularity=8 $(TARGET)
+	diff --ignore-case $(TARGET).signature.output $(TARGET).reference_output || exit
+	echo "Signature matches! Success!"
+
+clean:
+	rm -f $(TARGET).elf $(TARGET).objdump $(TARGET).objdump.adr %(TARGET).elf.memfile $(TARGET).signature.output
+
+
+

tests/custom/debug/debug.S

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+// debug.S
+// David_Harris@hmc.edu 4 February 2023
+// Small code snippets for the purpose of debugging issues
+// SPDX-License-Identifier: Apache-2.0 WITH SHL-2.1
+
+# openhwgroup/cvw Issue #55
+li x1, 0x7ff0000000000001
+fmv.w.x f4, x1
+li x1, 7ff8000000000000
+fmv.w.x f9, x1
+fsgnjx.s f12,f9,f4  # expected f 0xffffffff7fc00000
+
+
+#########################
+# HTIF and signature
+#########################
+
+write_tohost:
+    la t1, tohost
+    li t0, 1            # 1 for success, 3 for failure
+    sd t0, 0(t1)        # send success code
+
+self_loop:
+    j self_loop         # wait
+    
+.section .tohost 
+tohost:                 # write to HTIF
+    .dword 0
+fromhost:
+    .dword 0
+
+.data
+
+.EQU XLEN,64
+begin_signature:
+    .fill 2*(XLEN/32),4,0xdeadbeef    # 
+end_signature:
+
+# Initialize stack with room for 512 bytes
+.bss
+    .space 512
+topofstack: