Add fromWei in Utils.

src/Utils.php

@@ -160,6 +160,10 @@ class Utils
 
     /**
      * toWei
+     * Change number from unit to wei.
+     * For example:
+     * $wei = Utils::toWei('1', 'kwei'); 
+     * $wei->toString(); // 1000
      * 
      * @param BigNumber|string|int $number
      * @param string $unit
@@ -192,6 +196,10 @@ class Utils
 
     /**
      * toEther
+     * Change number from unit to ether.
+     * For example:
+     * list($bnq, $bnr) = Utils::toEther('1', 'kether'); 
+     * $bnq->toString(); // 1000
      * 
      * @param BigNumber|string|int $number
      * @param string $unit
@@ -207,4 +215,40 @@ class Utils
 
         return $wei->divide($bnt);
     }
+
+    /**
+     * fromWei
+     * Change number from wei to unit.
+     * For example:
+     * list($bnq, $bnr) = Utils::fromWei('1000', 'kwei'); 
+     * $bnq->toString(); // 1
+     * 
+     * @param BigNumber|string|int $number
+     * @param string $unit
+     * @return \phpseclib\Math\BigInteger
+     */
+    public static function fromWei($number, $unit)
+    {
+        if (is_int($number)) {
+            $bn = new BigNumber($number);
+        } elseif (is_string($number)) {
+            if (self::isZeroPrefixed($number)) {
+                $number = self::stripZero($number);
+                $bn = new BigNumber($number, 16);
+            } else {
+                $bn = new BigNumber($number);
+            }
+        } elseif (!$number instanceof BigNumber){
+            throw new InvalidArgumentException('fromWei number must be BigNumber, string or int.');
+        }
+        if (!is_string($unit)) {
+            throw new InvalidArgumentException('fromWei unit must be string.');
+        }
+        if (!isset(self::UNITS[$unit])) {
+            throw new InvalidArgumentException('fromWei doesn\'t support ' . $unit . ' unit.');
+        }
+        $bnt = new BigNumber(self::UNITS[$unit]);
+
+        return $bn->divide($bnt);
+    }
 }

test/unit/UtilsTest.php

@@ -180,4 +180,37 @@ class UtilsTest extends TestCase
         $this->assertEquals($bnq->toString(), '0');
         $this->assertEquals($bnr->toString(), '21016');
     }
+
+    /**
+     * testFromWei
+     * 
+     * @return void
+     */
+    public function testFromWei()
+    {
+        list($bnq, $bnr) = Utils::fromWei('1000000000000000000', 'ether');
+
+        $this->assertEquals($bnq->toString(), '1');
+        $this->assertEquals($bnr->toString(), '0');
+
+        list($bnq, $bnr) = Utils::fromWei('18', 'wei');
+
+        $this->assertEquals($bnq->toString(), '18');
+        $this->assertEquals($bnr->toString(), '0');
+
+        list($bnq, $bnr) = Utils::fromWei(1, 'femtoether');
+
+        $this->assertEquals($bnq->toString(), '0');
+        $this->assertEquals($bnr->toString(), '1');
+
+        list($bnq, $bnr) = Utils::fromWei(0x11, 'nano');
+
+        $this->assertEquals($bnq->toString(), '0');
+        $this->assertEquals($bnr->toString(), '17');
+
+        list($bnq, $bnr) = Utils::fromWei('0x5218', 'kwei');
+
+        $this->assertEquals($bnq->toString(), '21');
+        $this->assertEquals($bnr->toString(), '16');
+    }
 }