Allocate fewer objects when parsing 2 and 4 byte chunks.

This is achieved by adding getBytes2() and getBytes4() to streams, and by
changing int16() and int32() to take multiple scalar args instead of an array
arg.

src/core/chunked_stream.js

@@ -140,6 +140,20 @@ var ChunkedStream = (function ChunkedStreamClosure() {
       return this.bytes[this.pos++];
     },
 
+    getUint16: function ChunkedStream_getUint16() {
+      var b0 = this.getByte();
+      var b1 = this.getByte();
+      return (b0 << 8) + b1;
+    },
+
+    getUint32: function ChunkedStream_getUint32() {
+      var b0 = this.getByte();
+      var b1 = this.getByte();
+      var b2 = this.getByte();
+      var b3 = this.getByte();
+      return (b0 << 24) + (b1 << 16) + (b2 << 8) + b3;
+    },
+
     // returns subarray of original buffer
     // should only be read
     getBytes: function ChunkedStream_getBytes(length) {

src/core/fonts.js

@@ -2312,13 +2312,12 @@ var Font = (function FontClosure() {
     return strBuf.join('');
   }
 
-  function int16(bytes) {
-    return (bytes[0] << 8) + (bytes[1] & 0xff);
+  function int16(b0, b1) {
+    return (b0 << 8) + b1;
   }
 
-  function int32(bytes) {
-    return (bytes[0] << 24) + (bytes[1] << 16) +
-           (bytes[2] << 8) + (bytes[3] & 0xff);
+  function int32(b0, b1, b2, b3) {
+    return (b0 << 24) + (b1 << 16) + (b2 << 8) + b3;
   }
 
   function getMaxPower2(number) {
@@ -2397,8 +2396,8 @@ var Font = (function FontClosure() {
     // checksum
     var checksum = 0, n = data.length;
     for (var i = 0; i < n; i += 4)
-      checksum = (checksum + int32([data[i], data[i + 1], data[i + 2],
-                                    data[i + 3]])) | 0;
+      checksum = (checksum + int32(data[i], data[i + 1], data[i + 2],
+                                   data[i + 3])) | 0;
 
     var tableEntry = (tag + string32(checksum) +
                       string32(offset) + string32(length));
@@ -2626,21 +2625,21 @@ var Font = (function FontClosure() {
 
   function validateOS2Table(os2) {
     var stream = new Stream(os2.data);
-    var version = int16(stream.getBytes(2));
+    var version = stream.getUint16();
     // TODO verify all OS/2 tables fields, but currently we validate only those
     // that give us issues
     stream.getBytes(60); // skipping type, misc sizes, panose, unicode ranges
-    var selection = int16(stream.getBytes(2));
+    var selection = stream.getUint16();
     if (version < 4 && (selection & 0x0300)) {
       return false;
     }
-    var firstChar = int16(stream.getBytes(2));
-    var lastChar = int16(stream.getBytes(2));
+    var firstChar = stream.getUint16();
+    var lastChar = stream.getUint16();
     if (firstChar > lastChar) {
       return false;
     }
     stream.getBytes(6); // skipping sTypoAscender/Descender/LineGap
-    var usWinAscent = int16(stream.getBytes(2));
+    var usWinAscent = stream.getUint16();
     if (usWinAscent === 0) { // makes font unreadable by windows
       return false;
     }
@@ -2859,9 +2858,9 @@ var Font = (function FontClosure() {
               String.fromCharCode(tag[2]) +
               String.fromCharCode(tag[3]);
 
-        var checksum = int32(file.getBytes(4));
-        var offset = int32(file.getBytes(4));
-        var length = int32(file.getBytes(4));
+        var checksum = file.getUint32();
+        var offset = file.getUint32();
+        var length = file.getUint32();
 
         // Read the table associated data
         var previousPosition = file.pos;
@@ -2888,10 +2887,10 @@ var Font = (function FontClosure() {
       function readOpenTypeHeader(ttf) {
         return {
           version: arrayToString(ttf.getBytes(4)),
-          numTables: int16(ttf.getBytes(2)),
-          searchRange: int16(ttf.getBytes(2)),
-          entrySelector: int16(ttf.getBytes(2)),
-          rangeShift: int16(ttf.getBytes(2))
+          numTables: ttf.getUint16(),
+          searchRange: ttf.getUint16(),
+          entrySelector: ttf.getUint16(),
+          rangeShift: ttf.getUint16()
         };
       }
 
@@ -2903,8 +2902,8 @@ var Font = (function FontClosure() {
         var start = (font.start ? font.start : 0) + cmap.offset;
         font.pos = start;
 
-        var version = int16(font.getBytes(2));
-        var numTables = int16(font.getBytes(2));
+        var version = font.getUint16();
+        var numTables = font.getUint16();
 
         var potentialTable;
         var canBreak = false;
@@ -2915,9 +2914,9 @@ var Font = (function FontClosure() {
         // The following takes advantage of the fact that the tables are sorted
         // to work.
         for (var i = 0; i < numTables; i++) {
-          var platformId = int16(font.getBytes(2));
-          var encodingId = int16(font.getBytes(2));
-          var offset = int32(font.getBytes(4));
+          var platformId = font.getUint16();
+          var encodingId = font.getUint16();
+          var offset = font.getUint32();
           var useTable = false;
 
           if (platformId == 1 && encodingId === 0) {
@@ -2950,9 +2949,9 @@ var Font = (function FontClosure() {
         }
 
         font.pos = start + potentialTable.offset;
-        var format = int16(font.getBytes(2));
-        var length = int16(font.getBytes(2));
-        var language = int16(font.getBytes(2));
+        var format = font.getUint16();
+        var length = font.getUint16();
+        var language = font.getUint16();
 
         var hasShortCmap = false;
         var mappings = [];
@@ -2973,25 +2972,25 @@ var Font = (function FontClosure() {
         } else if (format === 4) {
           // re-creating the table in format 4 since the encoding
           // might be changed
-          var segCount = (int16(font.getBytes(2)) >> 1);
+          var segCount = (font.getUint16() >> 1);
           font.getBytes(6); // skipping range fields
           var segIndex, segments = [];
           for (segIndex = 0; segIndex < segCount; segIndex++) {
-            segments.push({ end: int16(font.getBytes(2)) });
+            segments.push({ end: font.getUint16() });
           }
-          font.getBytes(2);
+          font.getUint16();
           for (segIndex = 0; segIndex < segCount; segIndex++) {
-            segments[segIndex].start = int16(font.getBytes(2));
+            segments[segIndex].start = font.getUint16();
           }
 
           for (segIndex = 0; segIndex < segCount; segIndex++) {
-            segments[segIndex].delta = int16(font.getBytes(2));
+            segments[segIndex].delta = font.getUint16();
           }
 
           var offsetsCount = 0;
           for (segIndex = 0; segIndex < segCount; segIndex++) {
             var segment = segments[segIndex];
-            var rangeOffset = int16(font.getBytes(2));
+            var rangeOffset = font.getUint16();
             if (!rangeOffset) {
               segment.offsetIndex = -1;
               continue;
@@ -3005,7 +3004,7 @@ var Font = (function FontClosure() {
 
           var offsets = [];
           for (var j = 0; j < offsetsCount; j++) {
-            offsets.push(int16(font.getBytes(2)));
+            offsets.push(font.getUint16());
           }
 
           for (segIndex = 0; segIndex < segCount; segIndex++) {
@@ -3036,13 +3035,13 @@ var Font = (function FontClosure() {
           // table. (This looks weird, so I can have missed something), this
           // works on Linux but seems to fails on Mac so let's rewrite the
           // cmap table to a 3-1-4 style
-          var firstCode = int16(font.getBytes(2));
-          var entryCount = int16(font.getBytes(2));
+          var firstCode = font.getUint16();
+          var entryCount = font.getUint16();
 
           var glyphs = [];
           var ids = [];
           for (var j = 0; j < entryCount; j++) {
-            var glyphId = int16(font.getBytes(2));
+            var glyphId = font.getUint16();
             var charCode = firstCode + j;
 
             mappings.push({
@@ -3083,7 +3082,7 @@ var Font = (function FontClosure() {
 
         font.pos = (font.start ? font.start : 0) + header.offset;
         font.pos += header.length - 2;
-        var numOfMetrics = int16(font.getBytes(2));
+        var numOfMetrics = font.getUint16();
 
         if (numOfMetrics > numGlyphs) {
           info('The numOfMetrics (' + numOfMetrics + ') should not be ' +
@@ -3187,7 +3186,7 @@ var Font = (function FontClosure() {
 
         // Validate version:
         // Should always be 0x00010000
-        var version = int32([data[0], data[1], data[2], data[3]]);
+        var version = int32(data[0], data[1], data[2], data[3]);
         if (version >> 16 !== 1) {
           info('Attempting to fix invalid version in head table: ' + version);
           data[0] = 0;
@@ -3196,7 +3195,7 @@ var Font = (function FontClosure() {
           data[3] = 0;
         }
 
-        var indexToLocFormat = int16([data[50], data[51]]);
+        var indexToLocFormat = int16(data[50], data[51]);
         if (indexToLocFormat < 0 || indexToLocFormat > 1) {
           info('Attempting to fix invalid indexToLocFormat in head table: ' +
                indexToLocFormat);
@@ -3321,7 +3320,7 @@ var Font = (function FontClosure() {
         font.pos = start;
 
         var length = post.length, end = start + length;
-        var version = int32(font.getBytes(4));
+        var version = font.getUint32();
         // skip rest to the tables
         font.getBytes(28);
 
@@ -3332,14 +3331,14 @@ var Font = (function FontClosure() {
             glyphNames = MacStandardGlyphOrdering;
             break;
           case 0x00020000:
-            var numGlyphs = int16(font.getBytes(2));
+            var numGlyphs = font.getUint16();
             if (numGlyphs != maxpNumGlyphs) {
               valid = false;
               break;
             }
             var glyphNameIndexes = [];
             for (var i = 0; i < numGlyphs; ++i) {
-              var index = int16(font.getBytes(2));
+              var index = font.getUint16();
               if (index >= 32768) {
                 valid = false;
                 break;
@@ -3385,25 +3384,25 @@ var Font = (function FontClosure() {
 
         var names = [[], []];
         var length = nameTable.length, end = start + length;
-        var format = int16(font.getBytes(2));
+        var format = font.getUint16();
         var FORMAT_0_HEADER_LENGTH = 6;
         if (format !== 0 || length < FORMAT_0_HEADER_LENGTH) {
           // unsupported name table format or table "too" small
           return names;
         }
-        var numRecords = int16(font.getBytes(2));
-        var stringsStart = int16(font.getBytes(2));
+        var numRecords = font.getUint16();
+        var stringsStart = font.getUint16();
         var records = [];
         var NAME_RECORD_LENGTH = 12;
         for (var i = 0; i < numRecords &&
                         font.pos + NAME_RECORD_LENGTH <= end; i++) {
           var r = {
-            platform: int16(font.getBytes(2)),
-            encoding: int16(font.getBytes(2)),
-            language: int16(font.getBytes(2)),
-            name: int16(font.getBytes(2)),
-            length: int16(font.getBytes(2)),
-            offset: int16(font.getBytes(2))
+            platform: font.getUint16(),
+            encoding: font.getUint16(),
+            language: font.getUint16(),
+            name: font.getUint16(),
+            length: font.getUint16(),
+            offset: font.getUint16()
           };
           // using only Macintosh and Windows platform/encoding names
           if ((r.platform == 1 && r.encoding === 0 && r.language === 0) ||
@@ -3424,7 +3423,7 @@ var Font = (function FontClosure() {
             // unicode
             var str = '';
             for (var j = 0, jj = record.length; j < jj; j += 2) {
-              str += String.fromCharCode(int16(font.getBytes(2)));
+              str += String.fromCharCode(font.getUint16());
             }
             names[1][nameIndex] = str;
           } else {
@@ -3719,19 +3718,19 @@ var Font = (function FontClosure() {
       }
 
       font.pos = (font.start || 0) + tables.maxp.offset;
-      var version = int32(font.getBytes(4));
-      var numGlyphs = int16(font.getBytes(2));
+      var version = font.getUint32();
+      var numGlyphs = font.getUint16();
       var maxFunctionDefs = 0;
       if (version >= 0x00010000 && tables.maxp.length >= 22) {
         // maxZones can be invalid
         font.pos += 8;
-        var maxZones = int16(font.getBytes(2));
+        var maxZones = font.getUint16();
         if (maxZones > 2) { // reset to 2 if font has invalid maxZones
           tables.maxp.data[14] = 0;
           tables.maxp.data[15] = 2;
         }
         font.pos += 4;
-        maxFunctionDefs = int16(font.getBytes(2));
+        maxFunctionDefs = font.getUint16();
       }
 
       var dupFirstEntry = false;
@@ -3781,8 +3780,8 @@ var Font = (function FontClosure() {
       sanitizeHead(tables.head, numGlyphs, isTrueType ? tables.loca.length : 0);
 
       if (isTrueType) {
-        var isGlyphLocationsLong = int16([tables.head.data[50],
-                                          tables.head.data[51]]);
+        var isGlyphLocationsLong = int16(tables.head.data[50],
+                                         tables.head.data[51]);
         sanitizeGlyphLocations(tables.loca, tables.glyf, numGlyphs,
                                isGlyphLocationsLong, hintsValid, dupFirstEntry);
       }
@@ -3926,11 +3925,11 @@ var Font = (function FontClosure() {
         // extract some more font properties from the OpenType head and
         // hhea tables; yMin and descent value are always negative
         var override = {
-          unitsPerEm: int16([tables.head.data[18], tables.head.data[19]]),
-          yMax: int16([tables.head.data[42], tables.head.data[43]]),
-          yMin: int16([tables.head.data[38], tables.head.data[39]]) - 0x10000,
-          ascent: int16([tables.hhea.data[4], tables.hhea.data[5]]),
-          descent: int16([tables.hhea.data[6], tables.hhea.data[7]]) - 0x10000
+          unitsPerEm: int16(tables.head.data[18], tables.head.data[19]),
+          yMax: int16(tables.head.data[42], tables.head.data[43]),
+          yMin: int16(tables.head.data[38], tables.head.data[39]) - 0x10000,
+          ascent: int16(tables.hhea.data[4], tables.hhea.data[5]),
+          descent: int16(tables.hhea.data[6], tables.hhea.data[7]) - 0x10000
         };
 
         tables['OS/2'] = {

src/core/stream.js

@@ -40,6 +40,18 @@ var Stream = (function StreamClosure() {
         return -1;
       return this.bytes[this.pos++];
     },
+    getUint16: function Stream_getUint16() {
+      var b0 = this.getByte();
+      var b1 = this.getByte();
+      return (b0 << 8) + b1;
+    },
+    getUint32: function Stream_getUint32() {
+      var b0 = this.getByte();
+      var b1 = this.getByte();
+      var b2 = this.getByte();
+      var b3 = this.getByte();
+      return (b0 << 24) + (b1 << 16) + (b2 << 8) + b3;
+    },
     // returns subarray of original buffer
     // should only be read
     getBytes: function Stream_getBytes(length) {
@@ -143,6 +155,18 @@ var DecodeStream = (function DecodeStreamClosure() {
       }
       return this.buffer[this.pos++];
     },
+    getUint16: function DecodeStream_getUint16() {
+      var b0 = this.getByte();
+      var b1 = this.getByte();
+      return (b0 << 8) + b1;
+    },
+    getUint32: function DecodeStream_getUint32() {
+      var b0 = this.getByte();
+      var b1 = this.getByte();
+      var b2 = this.getByte();
+      var b3 = this.getByte();
+      return (b0 << 24) + (b1 << 16) + (b2 << 8) + b3;
+    },
     getBytes: function DecodeStream_getBytes(length) {
       var end, pos = this.pos;