Comprehensive fix (#46)

Author: neurolabusc

dist/src/nifti2.js

@@ -12,7 +12,7 @@ export declare class Utils {
     static getIntAt(data: DataView, start: number, littleEndian: boolean): number;
     static getFloatAt(data: DataView, start: number, littleEndian: boolean): number;
     static getDoubleAt(data: DataView, start: number, littleEndian: boolean): number;
-    static getLongAt(data: DataView, start: number, littleEndian: boolean): number;
+    static getInt64At(dataView: DataView, index: number, littleEndian: boolean): number;
     static getExtensionsAt(data: DataView, start: number, littleEndian: boolean, voxOffset: number): NIFTIEXTENSION[];
     static toArrayBuffer(buffer: TypedArray): ArrayBuffer;
     static isString(obj: Object): boolean;

dist/src/nifti2.js.map

@@ -129,7 +129,7 @@ export class NIFTI2 {
 
     for (ctr = 0; ctr < 8; ctr += 1) {
       index = 16 + ctr * 8;
-      this.dims[ctr] = Utils.getLongAt(rawData, index, this.littleEndian);
+      this.dims[ctr] = Utils.getInt64At(rawData, index, this.littleEndian);
     }
 
     this.intent_p1 = Utils.getDoubleAt(rawData, 80, this.littleEndian);
@@ -141,7 +141,7 @@ export class NIFTI2 {
       this.pixDims[ctr] = Utils.getDoubleAt(rawData, index, this.littleEndian);
     }
 
-    this.vox_offset = Utils.getLongAt(rawData, 168, this.littleEndian);
+    this.vox_offset = Utils.getInt64At(rawData, 168, this.littleEndian);
 
     this.scl_slope = Utils.getDoubleAt(rawData, 176, this.littleEndian);
     this.scl_inter = Utils.getDoubleAt(rawData, 184, this.littleEndian);
@@ -153,8 +153,8 @@ export class NIFTI2 {
 
     this.toffset = Utils.getDoubleAt(rawData, 216, this.littleEndian);
 
-    this.slice_start = Utils.getLongAt(rawData, 224, this.littleEndian);
-    this.slice_end = Utils.getLongAt(rawData, 232, this.littleEndian);
+    this.slice_start = Utils.getInt64At(rawData, 224, this.littleEndian);
+    this.slice_end = Utils.getInt64At(rawData, 232, this.littleEndian);
 
     this.description = Utils.getStringAt(rawData, 240, 240 + 80);
     this.aux_file = Utils.getStringAt(rawData, 320, 320 + 24);

dist/src/utilities.d.ts

@@ -64,20 +64,20 @@ export class Utils {
     return data.getFloat64(start, littleEndian);
   }
 
-  static getLongAt(data: DataView, start: number, littleEndian: boolean) {
-    var ctr,
-      array = [],
-      value = 0;
-
-    for (ctr = 0; ctr < 8; ctr += 1) {
-      array[ctr] = Utils.getByteAt(data, start + ctr);
+  static getInt64At(dataView: DataView, index: number, littleEndian: boolean): number {
+    const low = dataView.getUint32(index, littleEndian);
+    const high = dataView.getInt32(index + 4, littleEndian);
+    let result: number;
+    if (littleEndian) {
+        result = high * 2 ** 32 + low;
+    } else {
+      result = low * 2 ** 32 + high;
     }
-
-    for (ctr = array.length - 1; ctr >= 0; ctr--) {
-      value = value * 256 + array[ctr];
+    // Proper sign extension if the high part is negative
+    if (high < 0) {
+      result += -1 * 2 ** 32 * 2 ** 32;
     }
-
-    return value;
+    return result;
   }
 
   static getExtensionsAt(