Merge branch 'dev'

Author: cheton

dist/index.js

@@ -44,6 +44,19 @@ var removeSpaces = function removeSpaces(s) {
     return s.replace(/\s+/g, '');
 };
 
+// http://reprap.org/wiki/G-code#Special_fields
+// The checksum "cs" for a GCode string "cmd" (including its line number) is computed
+// by exor-ing the bytes in the string up to and not including the * character.
+var computeChecksum = function computeChecksum(s) {
+    var cs = 0;
+    s = s || '';
+    for (var i = 0; i < s.length; ++i) {
+        var c = s[i].charCodeAt(0);
+        cs = cs ^ c;
+    }
+    return cs;
+};
+
 var GCodeParser = (function (_Transform) {
     _inherits(GCodeParser, _Transform);
 
@@ -78,8 +91,8 @@ var GCodeParser = (function (_Transform) {
                     return;
                 }
 
-                var n = undefined;
-                var checksum = undefined;
+                var n = undefined; // Line number
+                var cs = undefined; // Checksum
                 var words = [];
                 var list = removeSpaces(line).match(/([a-zA-Z][0-9\+\-\.]*)|(\*[0-9]+)/igm) || [];
 
@@ -104,20 +117,28 @@ var GCodeParser = (function (_Transform) {
 
                     {
                         // *: Checksum
-                        if (letter === '*' && _lodash2.default.isUndefined(checksum)) {
-                            checksum = Number(argument);
+                        if (letter === '*' && _lodash2.default.isUndefined(cs)) {
+                            cs = Number(argument);
                             return;
                         }
                     }
 
                     words.push([letter, argument]);
                 });
 
+                // Exclude * (Checksum) from the line
+                if (line.lastIndexOf('*') >= 0) {
+                    line = line.substr(0, line.lastIndexOf('*'));
+                }
+
                 var obj = {};
                 obj.line = line;
                 obj.words = words;
-                typeof n !== 'undefined' && (obj.N = n); // N: Line number
-                typeof checksum !== 'undefined' && (obj.checksum = checksum); // *: Checksum
+                typeof n !== 'undefined' && (obj.N = n); // Line number
+                typeof cs !== 'undefined' && (obj.cs = cs); // Checksum
+                if (obj.cs && computeChecksum(line) !== obj.cs) {
+                    obj.err = true; // checksum failed
+                }
 
                 _this2.push(obj);
             });

index.js

@@ -19,6 +19,19 @@ const removeSpaces = (s) => {
     return s.replace(/\s+/g, '');
 };
 
+// http://reprap.org/wiki/G-code#Special_fields
+// The checksum "cs" for a GCode string "cmd" (including its line number) is computed
+// by exor-ing the bytes in the string up to and not including the * character.
+const computeChecksum = (s) => {
+    let cs = 0;
+    s = s || '';
+    for (let i = 0; i < s.length; ++i) {
+        let c = s[i].charCodeAt(0);
+        cs = cs ^ c;
+    }
+    return cs;
+};
+
 class GCodeParser extends Transform {
     constructor(options) {
         super(_.extend({}, options, { objectMode: true }));
@@ -43,8 +56,8 @@ class GCodeParser extends Transform {
                 return;
             }
 
-            let n;
-            let checksum;
+            let n; // Line number
+            let cs; // Checksum
             let words = [];
             let list = removeSpaces(line)
                 .match(/([a-zA-Z][0-9\+\-\.]*)|(\*[0-9]+)/igm) || [];
@@ -68,20 +81,28 @@ class GCodeParser extends Transform {
                 }
 
                 { // *: Checksum
-                    if (letter === '*' && _.isUndefined(checksum)) {
-                        checksum = Number(argument);
+                    if (letter === '*' && _.isUndefined(cs)) {
+                        cs = Number(argument);
                         return;
                     }
                 }
 
                 words.push([letter, argument]);
             });
 
+            // Exclude * (Checksum) from the line
+            if (line.lastIndexOf('*') >= 0) {
+                line = line.substr(0, line.lastIndexOf('*'));
+            }
+
             let obj = {};
             obj.line = line;
             obj.words = words;
-            (typeof(n) !== 'undefined') && (obj.N = n); // N: Line number
-            (typeof(checksum) !== 'undefined') && (obj.checksum = checksum); // *: Checksum
+            (typeof(n) !== 'undefined') && (obj.N = n); // Line number
+            (typeof(cs) !== 'undefined') && (obj.cs = cs); // Checksum
+            if (obj.cs && (computeChecksum(line) !== obj.cs)) {
+                obj.err = true; // checksum failed
+            }
 
             this.push(obj);
         });

package.json

@@ -1,6 +1,6 @@
 {
   "name": "gcode-parser",
-  "version": "0.4.0",
+  "version": "0.5.0",
   "description": "A G-code parser for Node.js",
   "author": "Cheton Wu <[email protected]>",
   "homepage": "https://github.com/cheton/gcode-parser",

test/fixtures/special-fields.gcode

@@ -3,4 +3,4 @@ N4 G92 E0*67
 N5 G28*22
 N6 G1 F1500.0*82
 N7 G1 X2.0 Y2.0 F3000.0*85
-N8 G1 X3.0 Y3.0*33
+N8 G1 X3.0 Y3.0*30 ; checksum failed

test/index.js

@@ -145,38 +145,39 @@ console.log(sampleText, err, results);
             let expectedResults = [
                 {
                     N: 3,
-                    checksum: 57,
-                    line: 'N3 T0*57',
+                    cs: 57,
+                    line: 'N3 T0',
                     words: [['T', 0]]
                 },
                 {
                     N: 4,
-                    checksum: 67,
-                    line: 'N4 G92 E0*67',
+                    cs: 67,
+                    line: 'N4 G92 E0',
                     words: [['G', 92], ['E', 0]]
                 },
                 {
                     N: 5,
-                    checksum: 22,
-                    line: 'N5 G28*22',
+                    cs: 22,
+                    line: 'N5 G28',
                     words: [['G', 28]]
                 },
                 {
                     N: 6,
-                    checksum: 82,
-                    line: 'N6 G1 F1500.0*82',
+                    cs: 82,
+                    line: 'N6 G1 F1500.0',
                     words: [['G', 1], ['F', 1500]]
                 },
                 {
                     N: 7,
-                    checksum: 85,
-                    line: 'N7 G1 X2.0 Y2.0 F3000.0*85',
+                    cs: 85,
+                    line: 'N7 G1 X2.0 Y2.0 F3000.0',
                     words: [['G', 1], ['X', 2], ['Y', 2], ['F', 3000]]
                 },
                 {
+                    err: true, // checksum failed
                     N: 8,
-                    checksum: 33,
-                    line: 'N8 G1 X3.0 Y3.0*33',
+                    cs: 30, // invalid checksum
+                    line: 'N8 G1 X3.0 Y3.0',
                     words: [['G', 1], ['X', 3], ['Y', 3]]
                 }
             ];