Add popc_stack command to gdb

assets/debugging/popcorn.elf-gdb.py

@@ -1,3 +1,28 @@
+import gdb
+
+class PrintStackCommand(gdb.Command):
+    def __init__(self):
+        super().__init__("popc_stack", gdb.COMMAND_DATA)
+
+    def invoke(self, arg, from_tty):
+        args = gdb.string_to_argv(arg)
+
+        base = "$rsp"
+        if len(args) > 0:
+            base = args[0]
+
+        depth = 22
+        if len(args) > 1:
+            depth = int(args[1])
+
+        for i in range(depth-1, -1, -1):
+            offset = i * 8
+            value = gdb.parse_and_eval(f"*(uint64_t*)({base} + {offset})")
+            print("{:04x}: {:016x}".format(offset, int(value)))
+
+
+PrintStackCommand()
+
 import time
 time.sleep(3.5)
 gdb.execute("target remote :1234")