add Min to SkNi, specialized for u8 and u16 on SSE and NEON

src/opts/SkNx_neon.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkNx_neon_DEFINED
 #define SkNx_neon_DEFINED
 
@@ skipping 311 matching lines @@
 
     void store(uint16_t vals[8]) const { vst1q_u16(vals, fVec); }
 
     SkNi operator + (const SkNi& o) const { return vaddq_u16(fVec, o.fVec); }
     SkNi operator - (const SkNi& o) const { return vsubq_u16(fVec, o.fVec); }
     SkNi operator * (const SkNi& o) const { return vmulq_u16(fVec, o.fVec); }
 
     SkNi operator << (int bits) const { SHIFT16(vshlq_n_u16, fVec, bits); }
     SkNi operator >> (int bits) const { SHIFT16(vshrq_n_u16, fVec, bits); }
 
+    static SkNi Min(const SkNi& a, const SkNi& b) { return vminq_u16(a.fVec, b.fVec); }
+
     template <int k> uint16_t kth() const {
         SkASSERT(0 <= k && k < 8);
         return vgetq_lane_u16(fVec, k&7);
     }
 
     uint16x8_t fVec;
 };
 
 template <>
 class SkNi<16, uint8_t> {
@@ skipping 15 matching lines @@
 
     SkNi saturatedAdd(const SkNi& o) const { return vqaddq_u8(fVec, o.fVec); }
 
     SkNi operator + (const SkNi& o) const { return vaddq_u8(fVec, o.fVec); }
     SkNi operator - (const SkNi& o) const { return vsubq_u8(fVec, o.fVec); }
     SkNi operator * (const SkNi& o) const { return vmulq_u8(fVec, o.fVec); }
 
     SkNi operator << (int bits) const { SHIFT8(vshlq_n_u8, fVec, bits); }
     SkNi operator >> (int bits) const { SHIFT8(vshrq_n_u8, fVec, bits); }
 
+    static SkNi Min(const SkNi& a, const SkNi& b) { return vminq_u8(a.fVec, b.fVec); }
+
     template <int k> uint8_t kth() const {
         SkASSERT(0 <= k && k < 15);
         return vgetq_lane_u8(fVec, k&16);
     }
 
     uint8x16_t fVec;
 };
 
 #undef SHIFT32
 #undef SHIFT16
 #undef SHIFT8
 
 #endif//SkNx_neon_DEFINED