Add name section support.

Resolves #2

README.md

@@ -83,6 +83,11 @@ As WebAssembly doesn't support unstructured jumps, control flow words (`IF/ELSE/
 However, since Forth only requires structured jumps, the compiler can easily be implemented 
 using the loop and branch instructions available in WebAssembly.
 
+Finally, the compiler adds minimal debug information about the compiled word in
+the [name section](https://github.com/WebAssembly/design/blob/master/BinaryEncoding.md#name-section), making it easier for doing some debugging in the browser.
+
+![Debugger view of a compiled word](https://el-tramo.be/blog/waforth/debugger.png "Debugger view of a compiled word")
+
 
 ### The Loader
 

src/shell/WAForth.js

@@ -60,12 +60,7 @@ class WAForth {
           if (index >= table.length) {
             table.grow(table.length); // Double size
           }
-          // console.log(
+          // console.log("Load", index, new Uint8Array(data), arrayToBase64(data));
-          //   "Load",
-          //   index,
-          //   new Uint8Array(data),
-          //   arrayToBase64(data)
-          // );
           var module = new WebAssembly.Module(data);
           new WebAssembly.Instance(module, {
             env: { table, tableBase: index, memory, tos: -1 }

src/tools/quadruple.wat

@@ -1,6 +1,6 @@
 ;; Template for defining 'word' modules
 ;; Used to 'reverse engineer' the binary code to emit from the compiler
-(module
+(module $quadruple
   (import "env" "table" (table 4 anyfunc))
   (import "env" "tableBase" (global $tableBase i32))
   (import "env" "memory" (memory 1))

src/waforth.wat

@@ -298,12 +298,12 @@
   ;; 6.1.0460
   (func $semicolon (param i32)
     (local $bodySize i32)
+    (local $nameLength i32)
 
     (call $emitEnd)
 
-    (set_local $bodySize (i32.sub (get_global $cp) (i32.const !moduleHeaderBase))) 
-    
     ;; Update code size
+    (set_local $bodySize (i32.sub (get_global $cp) (i32.const !moduleHeaderBase))) 
     (i32.store 
       (i32.const !moduleHeaderCodeSizeBase)
       (call $leb128-4p
@@ -322,8 +322,46 @@
       (i32.const !moduleHeaderLocalCountBase)
       (call $leb128-4p (get_global $localsCount)))
 
+    ;; Write a name section
+    (set_local $nameLength (i32.and (i32.load8_u (i32.add (get_global $latest) (i32.const 4)))
+                                    (i32.const !lengthMask)))
+    (i32.store8 (get_global $cp) (i32.const 0))
+    (i32.store8 (i32.add (get_global $cp) (i32.const 1)) 
+                (i32.add (i32.const 13) (i32.mul (i32.const 2) 
+                                                   (get_local $nameLength))))
+    (i32.store8 (i32.add (get_global $cp) (i32.const 2)) (i32.const 0x04))
+    (i32.store8 (i32.add (get_global $cp) (i32.const 3)) (i32.const 0x6e))
+    (i32.store8 (i32.add (get_global $cp) (i32.const 4)) (i32.const 0x61))
+    (i32.store8 (i32.add (get_global $cp) (i32.const 5)) (i32.const 0x6d))
+    (i32.store8 (i32.add (get_global $cp) (i32.const 6)) (i32.const 0x65))
+    (set_global $cp (i32.add (get_global $cp) (i32.const 7)))
+
+    (i32.store8 (get_global $cp) (i32.const 0x00))
+    (i32.store8 (i32.add (get_global $cp) (i32.const 1)) 
+                (i32.add (i32.const 1) (get_local $nameLength)))
+    (i32.store8 (i32.add (get_global $cp) (i32.const 2)) (get_local $nameLength)) 
+    (set_global $cp (i32.add (get_global $cp) (i32.const 3)))
+    (call $memcpy (get_global $cp)
+                  (i32.add (get_global $latest) (i32.const 5))
+                  (get_local $nameLength))
+    (set_global $cp (i32.add (get_global $cp) (get_local $nameLength)))
+
+    (i32.store8 (get_global $cp) (i32.const 0x01))
+    (i32.store8 (i32.add (get_global $cp) (i32.const 1)) 
+                (i32.add (i32.const 3) (get_local $nameLength)))
+    (i32.store8 (i32.add (get_global $cp) (i32.const 2)) (i32.const 0x01))
+    (i32.store8 (i32.add (get_global $cp) (i32.const 3)) (i32.const 0x00))
+    (i32.store8 (i32.add (get_global $cp) (i32.const 4)) (get_local $nameLength))
+    (set_global $cp (i32.add (get_global $cp) (i32.const 5)))
+    (call $memcpy (get_global $cp)
+                  (i32.add (get_global $latest) (i32.const 5))
+                  (get_local $nameLength))
+    (set_global $cp (i32.add (get_global $cp) (get_local $nameLength)))
+
     ;; Load the code and store the index
-    (call $shell_load (i32.const !moduleHeaderBase) (get_local $bodySize) (get_global $nextTableIndex))
+    (call $shell_load (i32.const !moduleHeaderBase) 
+                      (i32.sub (get_global $cp) (i32.const !moduleHeaderBase))
+                      (get_global $nextTableIndex))
     (i32.store (call $body (get_global $latest)) (get_global $nextTableIndex))
     (set_global $nextTableIndex (i32.add (get_global $nextTableIndex) (i32.const 1)))
 

tests/index.js

@@ -1012,6 +1012,10 @@ describe("WAForth", () => {
       expect(stack[1]).to.eql(4);
       expect(stack[2]).to.eql(5);
     });
+
+    it("should compile a name with an illegal WASM character", () => {
+      run(': F" 3 0 DO 2 LOOP ;');
+    });
   });
 
   describe("VARIABLE", () => {