Factor out UnPreMultiplyPreservingByteOrder

src/core/SkUnPreMultiply.cpp

 
 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #include "SkUnPreMultiply.h"
 #include "SkColorPriv.h"
 
 SkColor SkUnPreMultiply::PMColorToColor(SkPMColor c) {
     const unsigned a = SkGetPackedA32(c);
     const Scale scale = GetScale(a);
     return SkColorSetARGB(a,
                           ApplyScale(scale, SkGetPackedR32(c)),
                           ApplyScale(scale, SkGetPackedG32(c)),
                           ApplyScale(scale, SkGetPackedB32(c)));
 }
 
+uint32_t SkUnPreMultiply::UnPreMultiplyPreservingByteOrder(SkPMColor c) {
+    const U8CPU a = SkGetPackedA32(c);
+    const Scale scale = GetScale(a);
+    return SkPackARGB32NoCheck(a,
+                               ApplyScale(scale, SkGetPackedR32(c)),
+                               ApplyScale(scale, SkGetPackedG32(c)),
+                               ApplyScale(scale, SkGetPackedB32(c)));
+}
+
 const uint32_t SkUnPreMultiply::gTable[] = {
     0x00000000, 0xFF000000, 0x7F800000, 0x55000000, 0x3FC00000, 0x33000000, 0x2A800000, 0x246DB6DB,
     0x1FE00000, 0x1C555555, 0x19800000, 0x172E8BA3, 0x15400000, 0x139D89D9, 0x1236DB6E, 0x11000000,
     0x0FF00000, 0x0F000000, 0x0E2AAAAB, 0x0D6BCA1B, 0x0CC00000, 0x0C249249, 0x0B9745D1, 0x0B1642C8,
     0x0AA00000, 0x0A333333, 0x09CEC4EC, 0x0971C71C, 0x091B6DB7, 0x08CB08D4, 0x08800000, 0x0839CE74,
     0x07F80000, 0x07BA2E8C, 0x07800000, 0x07492492, 0x07155555, 0x06E45307, 0x06B5E50D, 0x0689D89E,
     0x06600000, 0x063831F4, 0x06124925, 0x05EE23B9, 0x05CBA2E9, 0x05AAAAAB, 0x058B2164, 0x056CEFA9,
     0x05500000, 0x05343EB2, 0x0519999A, 0x05000000, 0x04E76276, 0x04CFB2B8, 0x04B8E38E, 0x04A2E8BA,
     0x048DB6DB, 0x0479435E, 0x0465846A, 0x045270D0, 0x04400000, 0x042E29F8, 0x041CE73A, 0x040C30C3,
     0x03FC0000, 0x03EC4EC5, 0x03DD1746, 0x03CE540F, 0x03C00000, 0x03B21643, 0x03A49249, 0x03976FC6,
@@ skipping 41 matching lines @@
         // test the result
         for (int j = 1; j <= i; j++) {
             uint32_t test = (j * scale + (1 << 23)) >> 24;
             uint32_t div = roundf(j * 255.0f / i);
             int diff = SkAbs32(test - div);
             SkASSERT(diff <= 1 && test <= 255);
         }
     }
 }
 #endif