refactor: move isnan check from assign.js into main.js and utilize umul

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---

Author: impawstarlight

lib/node_modules/@stdlib/number/uint32/base/muldw/lib/assign.js

@@ -20,7 +20,7 @@
 
 // MODULES //
 
-var isnan = require( '@stdlib/math/base/assert/is-nan' );
+var umul = require( '@stdlib/number/uint32/base/mul' );
 
 
 // VARIABLES //
@@ -49,19 +49,13 @@ var LOW_WORD_MASK = 0x0000ffff>>>0; // asm type annotation
 function umuldw(a, b, out, stride, offset ) {
 	var w1;
 	var w2;
-	var w3;
 	var ha;
 	var hb;
 	var la;
 	var lb;
 	var t;
 	var k;
 
-	if ( isnan( a ) || isnan( b ) ) {
-		out[ offset ] = NaN;
-		out[ offset + stride ] = NaN;
-		return out;
-	}
 	a >>>= 0; // asm type annotation
 	b >>>= 0; // asm type annotation
 
@@ -72,7 +66,6 @@ function umuldw(a, b, out, stride, offset ) {
 	lb = ( b & LOW_WORD_MASK ) >>> 0;
 
 	t = ( la*lb ) >>> 0;
-	w3 = ( t & LOW_WORD_MASK ) >>> 0;
 	k = ( t >>> 16 ) >>> 0;
 
 	t = ( ( ha*lb ) + k ) >>> 0;
@@ -83,7 +76,7 @@ function umuldw(a, b, out, stride, offset ) {
 	k = ( t >>> 16 ) >>> 0;
 
 	out[ offset ] = ( ( ha*hb ) + w1 + k ) >>> 0; // compute the higher 32 bits and cast to an unsigned 32-bit integer
-	out[ offset + stride ] = ( ( t << 16 ) + w3) >>> 0; // compute the lower 32 bits and cast to an unsigned 32-bit integer
+	out[ offset + stride ] = umul(a, b) >>> 0; // compute the lower 32 bits and cast to an unsigned 32-bit integer
 
 	return out;
 }

lib/node_modules/@stdlib/number/uint32/base/muldw/lib/main.js

@@ -20,6 +20,7 @@
 
 // MODULES //
 
+var isnan = require( '@stdlib/math/base/assert/is-nan' );
 var fcn = require( './assign.js' );
 
 
@@ -37,6 +38,10 @@ var fcn = require( './assign.js' );
 * // returns [ 954437176, 1908874354 ]
 */
 function umuldw( a, b ) {
+	if ( isnan( a ) || isnan( b ) ) {
+		return [ NaN, NaN ];
+	}
+
 	return fcn( a, b, [ 0, 0 ], 1, 0 );
 }
 

lib/node_modules/@stdlib/number/uint32/base/muldw/test/test.assign.js

@@ -21,7 +21,6 @@
 // MODULES //
 
 var tape = require( 'tape' );
-var isnan = require( '@stdlib/math/base/assert/is-nan' );
 var Float64Array = require( '@stdlib/array/float64' );
 var umuldw = require( './../lib/assign.js' );
 
@@ -39,31 +38,6 @@ tape( 'main export is a function', function test( t ) {
 	t.end();
 });
 
-tape( 'the function returns `NaN` if provided `NaN`', function test( t ) {
-	var out;
-	var v;
-
-	out = [ 0, 0 ];
-	v = umuldw( NaN, 1, out, 1, 0 );
-	t.strictEqual( v, out, 'returns output array' );
-	t.strictEqual( isnan( v[0] ), true, 'returns expected value' );
-	t.strictEqual( isnan( v[1] ), true, 'returns expected value' );
-
-	out = [ 0, 0 ];
-	v = umuldw( 1, NaN, out, 1, 0 );
-	t.strictEqual( v, out, 'returns output array' );
-	t.strictEqual( isnan( v[0] ), true, 'returns expected value' );
-	t.strictEqual( isnan( v[1] ), true, 'returns expected value' );
-
-	out = [ 0, 0 ];
-	v = umuldw( NaN, NaN, out, 1, 0 );
-	t.strictEqual( v, out, 'returns output array' );
-	t.strictEqual( isnan( v[0] ), true, 'returns expected value' );
-	t.strictEqual( isnan( v[1] ), true, 'returns expected value' );
-
-	t.end();
-});
-
 tape( 'the function computes the double word product of two (unsigned) words', function test( t ) {
 	var expected;
 	var actual;