interpret: Remove state return argument

src/standalone/main.c

@@ -10,7 +10,13 @@
 
 #define CORE_TABLE_EXPORT_INDEX 0
 #define CORE_MEMORY_EXPORT_INDEX 1
-#define CORE_INTERPRET_EXPORT_INDEX 6
+#define CORE_ERROR_EXPORT_INDEX 6
+#define CORE_INTERPRET_EXPORT_INDEX 7
+
+#define ERR_UNKNOWN 0x1
+#define ERR_QUIT 0x2
+#define ERR_ABORT 0x3
+#define ERR_EOI 0x4
 
 wasm_memory_t *memory;
 wasm_table_t *table;
@@ -85,12 +91,8 @@ wasm_trap_t *load_cb(const wasm_val_vec_t *args, wasm_val_vec_t *results) {
   wasm_trap_t *trap = NULL;
   wasm_instance_t *instance = wasm_instance_new(store, module, &imports, &trap);
   if (!instance) {
-    printf("> Error instantiating loaded module!\n");
+    assert(trap != NULL);
-    if (trap) {
+    return trap;
-      print_trap(trap);
-      wasm_trap_delete(trap);
-    }
-    return trap_from_string("error instantiating module");
   }
   return NULL;
 }
@@ -108,8 +110,6 @@ wasm_trap_t *call_cb(void *env, const wasm_val_vec_t *args, wasm_val_vec_t *resu
 ////////////////////////////////////////////////////////////////////////////////
 
 int main(int argc, char *argv_main[]) {
-  int ret = -1;
-
   wasm_engine_t *engine = wasm_engine_new();
   store = wasm_store_new(engine);
   wasm_byte_vec_t core = {.data = (wasm_byte_t *)waforth_core, .size = sizeof(waforth_core)};
@@ -156,7 +156,7 @@ int main(int argc, char *argv_main[]) {
   wasm_extern_vec_t exports;
   wasm_instance_exports(instance, &exports);
   if (exports.size == 0) {
-    printf("error accessing export\n");
+    printf("error accessing exports\n");
     return -1;
   }
 
@@ -178,27 +178,43 @@ int main(int argc, char *argv_main[]) {
     return -1;
   }
 
+  const wasm_func_t *error_fn = wasm_extern_as_func(exports.data[CORE_ERROR_EXPORT_INDEX]);
+  if (error_fn == NULL) {
+    printf("error accessing `error` export\n");
+    return -1;
+  }
+
   printf("WAForth (" VERSION ")\n");
-  wasm_val_t as[1] = {WASM_I32_VAL(0)};
+  wasm_val_t interpret_as[1] = {WASM_I32_VAL(0)};
-  wasm_val_vec_t args = WASM_ARRAY_VEC(as);
+  wasm_val_vec_t interpret_args = WASM_ARRAY_VEC(interpret_as);
-  wasm_val_t vs[] = {WASM_INIT_VAL};
+  wasm_val_vec_t interpret_results = WASM_EMPTY_VEC;
-  wasm_val_vec_t results_vec = WASM_ARRAY_VEC(vs);
+
-  while (true) {
+  wasm_val_vec_t err_args = WASM_EMPTY_VEC;
-    trap = wasm_func_call(interpret_fn, &args, &results_vec);
+  wasm_val_t err_results_vs[] = {WASM_INIT_VAL};
-    if (trap == NULL) {
+  wasm_val_vec_t err_results = WASM_ARRAY_VEC(err_results_vs);
-      // No trap means the input buffer was no longer filled when asked.
+
-      // This means the program should exit.
+  for (int stopped = 0; !stopped;) {
+    trap = wasm_func_call(interpret_fn, &interpret_args, &interpret_results);
+    wasm_trap_t *etrap = wasm_func_call(error_fn, &err_args, &err_results);
+    assert(etrap == NULL);
+    switch (err_results.data[0].of.i32) {
+    case ERR_QUIT:
+    case ERR_ABORT:
+      assert(trap != NULL);
+      wasm_trap_delete(trap);
       break;
+    case ERR_EOI:
+      assert(trap == NULL);
+      stopped = true;
+      break;
+    case ERR_UNKNOWN:
+      assert(trap != NULL);
+      print_trap(trap);
+      wasm_trap_delete(trap);
+      break;
+    default:
+      assert(false);
     }
-    wasm_name_t message;
-    wasm_trap_message(trap, &message);
-    // `unreachable` is called when we want to reset the call stack, and start the interpreter
-    // loop again (i.e. when QUIT is called)
-    if (strstr(message.data, "wasm `unreachable` instruction executed") == NULL) {
-      printf("error: %s\n", message.data);
-    }
-    wasm_name_delete(&message);
-    wasm_trap_delete(trap);
   }
 
   wasm_extern_vec_delete(&exports);
@@ -211,5 +227,5 @@ int main(int argc, char *argv_main[]) {
   wasm_module_delete(module);
   wasm_store_delete(store);
   wasm_engine_delete(engine);
-  return ret;
+  return 0;
 }

src/waforth.wat

@@ -708,8 +708,10 @@
 
   ;; 6.1.0670 ABORT 
   (func $ABORT (param $tos i32) (result i32)
-    (call $QUIT (i32.const 0x10000 (; = STACK_BASE ;))))
+    (global.set $error (i32.const 0x3 (; = ERR_ABORT ;)))
+    (call $quit (i32.const 0x10000 (; = STACK_BASE ;))))
   (data (i32.const 0x202d0) "\c4\02\02\00" "\05" "ABORT  " "\3b\00\00\00")
+  (elem (i32.const 0x3b) $ABORT)
 
   ;; 6.1.0680 ABORT"
   (func $ABORTq (param $tos i32) (result i32)
@@ -1059,7 +1061,7 @@
     (global.set $inputBufferSize (i32.load (i32.sub (local.get $tos) (i32.const 4))))
     (i32.store (i32.const 0x20294 (; = body(>IN) ;)) (i32.const 0))
 
-    (drop (call $interpret (local.get $bbtos)))
+    (call $interpret (local.get $bbtos))
 
     ;; Restore input state
     (global.set $sourceID (local.get $prevSourceID))
@@ -1393,11 +1395,8 @@
 
   ;; 6.1.2050
   (func $QUIT (param $tos i32) (result i32)
-    (global.set $tos (local.get $tos))
+    (global.set $error (i32.const 0x2 (; = ERR_QUIT ;)))
-    (global.set $tors (i32.const 0x2000 (; = RETURN_STACK_BASE ;)))
+    (call $quit (local.get $tos)))
-    (global.set $sourceID (i32.const 0))
-    (i32.store (i32.const 0x207bc (; = body(STATE) ;)) (i32.const 0))
-    (unreachable))
   (data (i32.const 0x206ac) "\98\06\02\00" "\04" "QUIT   " "\7b\00\00\00")
   (elem (i32.const 0x7b) $QUIT)
 
@@ -1851,7 +1850,7 @@
   ;; Interprets the string in the input, until the end of string is reached.
   ;; Returns 0 if processed, 1 if still compiling, or traps if a word 
   ;; was not found.
-  (func $interpret (param $tos i32) (result i32) (result i32)
+  (func $interpret (param $tos i32) (result i32)
     (local $FINDResult i32)
     (local $FINDToken i32)
     (local $error i32)
@@ -1897,8 +1896,7 @@
                 ;; We're compiling a non-immediate
                 (local.set $tos (call $compileCall (local.get $tos) (local.get $FINDToken)))))))
           (br $loop)))
-    (local.get $tos)
+    (local.get $tos))
-    (i32.load (i32.const 0x207bc (; = body(STATE) ;))))
 
   ;; Returns (number, unparsed length)
   (func $readNumber (param $addr i32) (param $len i32) (result i32 i32)
@@ -1962,6 +1960,13 @@
     (i64.mul (local.get $sign) (local.get $value))
     (local.get $p) 
     (i32.sub (local.get $end) (local.get $p)))
+  
+  (func $quit (param $tos i32) (result i32)
+    (global.set $tos (local.get $tos))
+    (global.set $tors (i32.const 0x2000 (; = RETURN_STACK_BASE ;)))
+    (global.set $sourceID (i32.const 0))
+    (i32.store (i32.const 0x207bc (; = body(STATE) ;)) (i32.const 0))
+    (unreachable))
 
   ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
   ;; Interpreter state
@@ -1988,6 +1993,17 @@
   ;; Pictured output pointer
   (global $po (mut i32) (i32.const -1))
 
+  ;; Error code
+  ;; 
+  ;; This can only be inspected after an interpret() call (using error()).
+  ;;
+  ;; Values:
+  ;;   ERR_UNKNOWN := 0x1   (Unknown error, e.g. exception during one of the `shell` functions)
+  ;;   ERR_QUIT :=    0x2   (QUIT called)
+  ;;   ERR_ABORT :=   0x3   (ABORT or ABORT" called)
+  ;;   ERR_EOI :=     0x4   (No more user input received)
+  (global $error (mut i32) (i32.const 0x0))
+
   ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
   ;; Compiler functions
   ;;
@@ -2734,17 +2750,20 @@
   
   (func (export "here") (result i32)
     (global.get $here))
+  
+  (func (export "error") (result i32)
+    (global.get $error))
 
-  (func (export "interpret") (param $silent i32) (result i32)
+  (func (export "interpret") (param $silent i32)
-    (local $result i32)
+    (local $state i32)
     (local $tos i32)
     (local.tee $tos (global.get $tos))
+    (global.set $error (i32.const 0x1 (; = ERR_UNKNOWN ;)))
     (block $endLoop (param i32) (result i32)
       (loop $loop (param i32) (result i32)
         (call $REFILL)
         (br_if $endLoop (i32.eqz (call $pop)))
-        (local.set $result (call $interpret))
+        (local.set $tos (call $interpret))
-        (local.set $tos)
 
         ;; Check for stack underflow
         (if (i32.lt_s (local.get $tos) (i32.const 0x10000 (; = STACK_BASE ;)))
@@ -2753,7 +2772,7 @@
         ;; Show prompt
         (if (i32.eqz (local.get $silent))
           (then
-            (if (i32.ge_s (local.get $result) (i32.const 0))
+            (if (i32.ge_s (i32.load (i32.const 0x207bc (; = body(STATE) ;))) (i32.const 0))
               (then
                 ;; Write ok
                 (call $shell_emit (i32.const 111))
@@ -2769,7 +2788,7 @@
         (local.get $tos)
         (br $loop)))
       (global.set $tos)
-      (local.get $result))
+      (global.set $error (i32.const 0x4 (; = ERR_EOI ;))))
 
   (func (export "push") (param $v i32)
     (global.set $tos (call $push (global.get $tos) (local.get $v))))

src/web/tests/suite.js

@@ -93,15 +93,15 @@ function loadTests() {
     }
 
     function run(s, expectErrors = false) {
-      const r = forth.interpret(s, true);
+      forth.interpret(s, true);
+      const r = forth.core.exports.error();
       if (expectErrors) {
-        expect(r).to.be.undefined;
+        expect(r).to.not.eql(4);
       } else {
-        expect(r).to.not.be.an(
+        expect(r).to.eql(
-          "undefined",
+          4,
-          "Error running: " + s + "; Output: " + output
+          "Error " + r + " running: " + s + "; Output: " + output
         );
-        expect(r).to.not.be.below(0);
       }
     }
 
@@ -197,18 +197,21 @@ function loadTests() {
 
       it("should interpret a positive number", () => {
         forth.read("123");
-        expect(core.interpret()).to.eql(0);
+        core.interpret();
+        expect(core.error()).to.eql(4);
         expect(stackValues()[0]).to.eql(123);
       });
 
       it("should interpret a negative number", () => {
         forth.read("-123");
-        expect(core.interpret()).to.eql(0);
+        core.interpret();
+        expect(core.error()).to.eql(4);
         expect(stackValues()[0]).to.eql(-123);
       });
       it("should interpret a hex", () => {
         forth.read("16 BASE ! DF");
-        expect(core.interpret()).to.eql(0);
+        core.interpret();
+        expect(core.error()).to.eql(4);
         expect(stackValues()[0]).to.eql(223);
       });
       it("should not interpret hex in decimal mode", () => {

src/web/waforth.ts

@@ -36,6 +36,13 @@ function saveString(s: string, memory: WebAssembly.Memory, addr: number) {
   }
 }
 
+enum ErrorCode {
+  Unknown = 0x1, // Unknown error
+  Quit = 0x2, // QUIT was called
+  Abort = 0x3, // ABORT or ABORT" was called
+  EOI = 0x4, // No more input
+}
+
 /**
  * JavaScript shell around the WAForth WebAssembly module.
  *
@@ -235,8 +242,12 @@ class WAForth {
       return (this.core!.exports.interpret as any)(silent);
     } catch (e) {
       // Exceptions thrown from the core means QUIT or ABORT is called, or an error
-      // has occurred. Assume what has been done has been done, and ignore here.
+      // has occurred.
+      if ((this.core!.exports.error as any)() === ErrorCode.Unknown) {
+        console.error(e);
+      }
     }
+    return (this.core!.exports.error as any)() as ErrorCode;
   }
 
   /**