M examples/on-error.xyw → examples/on-error.xyw

@@ -9,13 +9,13 @@ end JMPw
 
 ; on error handler
 .label on_error
-    system.error $1 EQU on_error.div-by-zero.print JCNw
+    system.error LDB $1 EQU on_error.div-by-zero.print JCNw
     unknown-error print JSRw
     $0 system.error STB
     RTS
     .label on_error.div-by-zero.print
         div-by-zero-error print JSRw
-        $0 system.error STB
+        $3 system.error STB
         RTS
 
 ; printing subroutine

M test.sh → test.sh

@@ -5,7 +5,7 @@ ### Test cases
 TEST_CASES=(
   "run_test helloworld.xyw assert_output_equals \$'Hello, World!\\n'"
   "run_test d6.xyw assert_output_in_range 1 6"
-  "run_test on-error.xyw assert_output_equals \$'Error: Division by zero.\\n'"
+  "run_test on-error.xyw assert_output_equals \$'Error: Division by zero.\\nError: Unknown error.\\n'"
 )
 
 ### Helper functions

M xywrun.c → xywrun.c

@@ -298,24 +298,23 @@ //// Returns 1 on success, 0 on error
 int xyw_eval(xyw_word start_pc)
 {
     *pc = start_pc;
-    xyw_byte handler_entry_s = 0; // Track stack depth when entering error handler
+    xyw_byte error_handler_entry_s = 0;
 
     if (xyw_memory[SYSTEM_STATE] & xyw_debug)
     {
         xyw_memory[SYSTEM_STATE] |= SYSTEM_STATE_DEBUG;
     }
-
     while ((xyw_memory[SYSTEM_STATE] & SYSTEM_STATE_RUNNING) && *pc < SYSTEM_MEMORY_START)
     {
         if (xyw_memory[SYSTEM_ERROR] != XYW_ERROR_NONE && !(xyw_memory[SYSTEM_STATE] & SYSTEM_STATE_ERROR))
         {
-            // An error has occurred, update state
-            xyw_memory[SYSTEM_STATE] |= SYSTEM_STATE_ERROR;
             xyw_word on_error_handler = XYW_PEEKW(&xyw_memory[SYSTEM_ON_ERROR]);
             // If an error handler is set, jump to it
             if (on_error_handler != 0)
             {
-                handler_entry_s = *s; // Record stack depth before pushing return address
+                // Enter error state
+                xyw_memory[SYSTEM_STATE] |= SYSTEM_STATE_ERROR;
+                error_handler_entry_s = *s; // Record stack depth before pushing return address
                 ss_pushw(*pc);
                 *pc = on_error_handler;
             }
@@ -376,8 +375,9 @@ /* JSR */ OPC_SR1(0x1E, xyw_word addr = ADDR(ARG),  ss_pushw(*pc+1); *pc = addr-1;);
             /* RTS */ case 0x1F: 
                 *pc = ss_popw()-1; 
                 // If returning from error handler, clear flag to allow re-trigger
-                if ((xyw_memory[SYSTEM_STATE] & SYSTEM_STATE_ERROR) && *s == handler_entry_s) {
+                if ((xyw_memory[SYSTEM_STATE] & SYSTEM_STATE_ERROR) && *s == error_handler_entry_s) {
                     xyw_memory[SYSTEM_STATE] &= ~SYSTEM_STATE_ERROR;
+                    error_handler_entry_s = 0;
                 }
                 break;
             // clang-format on