docs: document watchpoint slot tracking and update debugger commands

debug/repl.go

@@ -384,8 +384,8 @@ func REPL(s *Session, bm *Breakpoints, codeBase uint64, funcOffset, funcSize, ar
 			fmt.Println(`  break <label|addr> [if <reg> <op> <val>]  set a breakpoint
   delete <label|addr>  remove a breakpoint
   info break           list all breakpoints
-  watch <addr> [r|w]   set a hardware watchpoint (write by default)
-  unwatch              clear all watchpoints
+  watch <addr> [r|w] [size]  set a hardware watchpoint (write by default)
+  unwatch [<slot>]     clear one or all watchpoints
   step [n], s          single-step n instructions
   next, n              step over CALL
   continue, c          run until breakpoint or exit
@@ -457,28 +457,39 @@ func REPL(s *Session, bm *Breakpoints, codeBase uint64, funcOffset, funcSize, ar
 			if len(parts) > 3 {
 				size, _ = strconv.Atoi(parts[3])
 			}
-			// Find a free slot (0-3).
-			slot := -1
-			for i := 0; i < 4; i++ {
-				// Simple: use slot 0 for now.
-				slot = i
-				break
-			}
+			slot := s.FindFreeWatchpointSlot()
 			if slot < 0 {
-				fmt.Println("no free watchpoint slots")
+				fmt.Println("no free watchpoint slots (use 'unwatch <slot>' to clear one)")
 				continue
 			}
 			if err := s.SetWatchpoint(slot, addr, typ, size); err != nil {
 				fmt.Printf("watch: %v\n", err)
 			} else {
-				fmt.Printf("watchpoint %d set: %#x (%s, %d bytes)\n", slot, addr, parts[2], size)
+				typStr := "w"
+				if typ == WatchRead {
+					typStr = "r"
+				}
+				fmt.Printf("watchpoint %d set: %#x (%s, %d bytes)\n", slot, addr, typStr, size)
 			}
 
 		case "unwatch":
-			if err := s.ClearAllWatchpoints(); err != nil {
-				fmt.Printf("unwatch: %v\n", err)
+			if len(parts) >= 2 {
+				slot, err := strconv.Atoi(parts[1])
+				if err != nil || slot < 0 || slot > 3 {
+					fmt.Println("usage: unwatch [<slot>]")
+					continue
+				}
+				if err := s.ClearWatchpoint(slot); err != nil {
+					fmt.Printf("unwatch: %v\n", err)
+				} else {
+					fmt.Printf("watchpoint %d cleared\n", slot)
+				}
 			} else {
-				fmt.Println("all watchpoints cleared")
+				if err := s.ClearAllWatchpoints(); err != nil {
+					fmt.Printf("unwatch: %v\n", err)
+				} else {
+					fmt.Println("all watchpoints cleared")
+				}
 			}
 
 		default: