Populate all traps from 0x0000-0xFFFF with a NOP.

This means the CPU doesn't need to report a warning/error.

Also updated the trap-signature such that each invoked handler
knows what number it was called by - which might be useful in
future.

cpu/cpu.go

@@ -720,14 +720,11 @@ func (c *CPU) Run() {
  debugPrintf("TRAP\n")
  c.ip += 1
 
- addr := c.read2Val()
+ num := c.read2Val()
 
- fn := TRAPS[addr]
+ fn := TRAPS[num]
  if fn != nil {
- fn(c)
- } else {
- fmt.Printf("Trap function not defined: 0x%04X\n", addr)
-
+ fn(c, num)
  }
  default:
  fmt.Printf("Unrecognized/Unimplemented opcode %02X at IP %04X\n", instruction, c.ip)

cpu/traps.go

@@ -8,14 +8,15 @@ package cpu
 
 import (
  "bufio"
+ "fmt"
  "os"
 )
 
 //
 // TrapFunction is the signature for a function that is available
 // as a trap.
 //
-type TrapFunction func(c *CPU)
+type TrapFunction func(c *CPU, num int)
 
 //
 // Create an array of trap-functions.
@@ -31,14 +32,18 @@ var reader *bufio.Reader
 // Trap Functions now follow
 //
 
+func TrapNOP(c *CPU, num int) {
+ fmt.Printf("Trap function not defined: 0x%04X\n", num)
+}
+
 // StrLenTrap returns the length of a string.
 //
 // Input:
 // The string to measure in register 0.
 // Output:
 // Sets register 0 with the length
 //
-func StrLenTrap(c *CPU) {
+func StrLenTrap(c *CPU, num int) {
  str := c.regs[0].GetString()
  c.regs[0].SetInt(len(str))
 }
@@ -50,7 +55,7 @@ func StrLenTrap(c *CPU) {
 // Ouptut:
 // Sets register 0 with the user-provided string
 //
-func ReadStringTrap(c *CPU) {
+func ReadStringTrap(c *CPU, num int) {
  text, _ := reader.ReadString('\n')
  c.regs[0].SetString(text)
 }
@@ -61,4 +66,13 @@ func init() {
  reader = bufio.NewReader(os.Stdin)
  TRAPS[0] = StrLenTrap
  TRAPS[1] = ReadStringTrap
+
+ // Fill in the rest of the traps with
+ // a function that will just report that
+ // the given ID is not implemented
+ for i := 0; i < 0xFFFF; i++ {
+ if TRAPS[i] == nil {
+ TRAPS[i] = TrapNOP
+ }
+ }
 }

examples/trap.missing.in

@@ -0,0 +1,18 @@
+#
+# About:
+#
+# This program demonstrates the invokation of a trap-function which isn't
+# implemented.
+#
+# Usage:
+#
+# $ go.vm run ./trap.missing.in
+#
+# Or compile, then execute:
+#
+# $ go.vm compile ./trap.missing.in
+# $ go.vm execute ./trap.missing.raw
+#
+
+ # Call the trap
+ int 0xf00f