diff --git a/c_util b/c_util
index 1482ea1d..955e9d88 100755
--- a/c_util
+++ b/c_util
@@ -531,6 +531,12 @@ def parse_function(lines_info, start_idx):
     }
 
 
+def line_checksum(line):
+    """Calculate checksum: sum of all character codes modulo 256, as 2 hex digits."""
+    checksum = sum(ord(c) for c in line) % 256
+    return f"{checksum:02X}"
+
+
 def normalize_whitespace(text):
     """Normalize whitespace: replace multiple spaces/newlines with single space."""
     # Replace all whitespace (spaces, tabs, newlines) with single space
@@ -774,13 +780,26 @@ def main():
             # Print declarations with full formatting
             for start, end, decl_type, content, extra in declarations:
                 if decl_type == 'function':
-                    # Print comments first if any
+                    # Print comments first if any (without line numbers)
                     if extra:
                         print(extra)
-                    print(f"[{start + 1}-{end + 1}] {content}")
+                    # Print function signature with line number and checksum
+                    lines = contents[f]
+                    for line_idx in range(start, end + 1):
+                        if line_idx < len(lines):
+                            line = lines[line_idx]
+                            line_num = line_idx + 1
+                            checksum = line_checksum(line)
+                            print(f"{line_num} {checksum}: {line}")
                 else:
-                    # struct or enum - print with preserved formatting on multiple lines
-                    print(f"[{start + 1}-{end + 1}] {extra}")
+                    # struct or enum - print with line numbers and checksums
+                    lines = contents[f]
+                    for line_idx in range(start, end + 1):
+                        if line_idx < len(lines):
+                            line = lines[line_idx]
+                            line_num = line_idx + 1
+                            checksum = line_checksum(line)
+                            print(f"{line_num} {checksum}: {line}")
     
     elif cmd == 'show':
         if len(sys.argv) < 3:
@@ -830,14 +849,25 @@ def main():
             # Print filename header
             print(f"{f}:")
             
-            # Print items
+            # Print items with line numbers and checksums
             for item_type, item in items:
                 lines = contents[f]
+                start = item['start']
+                end = item['end']
+                
+                # Print pre lines (comments) without line numbers
                 pre = item['pre']
-                body = lines[item['start']:item['end'] + 1]
                 if pre:
-                    print('\n'.join(pre))
-                print('\n'.join(body))
+                    for pre_line in pre:
+                        print(pre_line)
+                
+                # Print body with line numbers and checksums
+                for line_idx in range(start, end + 1):
+                    if line_idx < len(lines):
+                        line = lines[line_idx]
+                        line_num = line_idx + 1
+                        checksum = line_checksum(line)
+                        print(f"{line_num} {checksum}: {line}")
         
         if not found_any:
             print("Not found")