Add .def support

asm.js

@@ -93,6 +93,8 @@ const State = Object.freeze({
     WORD:         21,
     UTF8:         22,
     ALIGN:        23,
+    DEF_NAME:     24,
+    DEF_VALUE:    25,
 });
 
 const Action = Object.freeze({
@@ -109,6 +111,7 @@ const Action = Object.freeze({
     AT:     10,
     DATA:   11,
     ALIGN:  12,
+    DEF:    13,
 });
 
 const types = {
@@ -157,6 +160,7 @@ class Parser {
             ".word":   State.WORD,
             ".utf8":   State.UTF8,
             ".align":  State.ALIGN,
+            ".def":    State.DEF_NAME,
         };
         this.handlers = {
             [State.TOP]:          (token) => this.token_top(token),
@@ -183,6 +187,8 @@ class Parser {
             [State.WORD]:         (token) => this.token_word(token),
             [State.UTF8]:         (token) => this.token_utf8(token),
             [State.ALIGN]:        (token) => this.token_align(token),
+            [State.DEF_NAME]:     (token) => this.token_def_name(token),
+            [State.DEF_VALUE]:    (token) => this.token_def_value(token),
         };
 
         this.results = [];
@@ -538,6 +544,40 @@ class Parser {
         return action;
     }
 
+    token_def_name(token) {
+        if (token == LINE_END) {
+            console.error("ERROR: Unexpected end of line, expected name");
+            this.state = State.TOP;
+            return;
+        }
+        this.def_name = token;
+        this.state = State.DEF_VALUE;
+    }
+
+    token_def_value(token) {
+        if (token == LINE_END) {
+            console.error("ERROR: Unexpected end of line, expected value");
+            this.def_name = undefined;
+            this.state = State.TOP;
+            return;
+        }
+        const value = this.integer(token);
+        if (value == null) {
+            console.error(
+                `ERROR: Unexpected token ${token}, expected value`);
+            this.def_name = undefined;
+            this.state = State.TOP;
+            return;
+        }
+        const action = {
+            type: Action.DEF,
+            def: { name: this.def_name, value },
+        };
+        this.def_name = undefined;
+        this.state = State.TOP;
+        return action;
+    }
+
     mem_action() {
         const action = {
             type: Action.MEM,
@@ -593,6 +633,7 @@ export class Assembler {
             [Action.AT]:     (action) => this.action_at(action),
             [Action.DATA]:   (action) => this.action_data(action),
             [Action.ALIGN]:  (action) => this.action_align(action),
+            [Action.DEF]:    (action) => this.action_def(action),
         };
 
         this.exports = [];
@@ -602,6 +643,7 @@ export class Assembler {
         this.globals = {};
         this.pos = { mem: 0, addr: 0 };
         this.data = [];
+        this.defs = {};
 	}
 
     action_append(action) {
@@ -694,6 +736,10 @@ export class Assembler {
         }
     }
 
+    action_def(action) {
+        this.defs[action.def.name] = action.def.value;
+    }
+
 	push(chunk) {
 		const text = this.decoder.decode(chunk, { stream: true });
 		for (const action of this.parser.handle(text))