Revert of SkPx: new approach to fixed-point SIMD

src/opts/SkPx_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 SkPx_neon_DEFINED
-#define SkPx_neon_DEFINED
-
-// When we have NEON, we like to work 8 pixels at a time.
-// This lets us exploit vld4/vst4 and represent SkPx as planar uint8x8x4_t,
-// Wide as planar uint16x8x4_t, and Alpha as a single uint8x8_t plane.
-
-struct SkPx_neon {
-    static const int N = 8;
-
-    uint8x8x4_t fVec;
-    SkPx_neon(uint8x8x4_t vec) : fVec(vec) {}
-
-    static SkPx_neon Dup(uint32_t px) { return vld4_dup_u8((const uint8_t*)&px); }
-    static SkPx_neon Load(const uint32_t* px) { return vld4_u8((const uint8_t*)px); }
-    static SkPx_neon Load(const uint32_t* px, int n) {
-        SkASSERT(0 < n && n < 8);
-        uint8x8x4_t v = vld4_dup_u8((const uint8_t*)px);  // n>=1, so start all lanes with pixel 0.
-        switch (n) {
-            case 7: v = vld4_lane_u8((const uint8_t*)(px+6), v, 6);  // fall through
-            case 6: v = vld4_lane_u8((const uint8_t*)(px+5), v, 5);  // fall through
-            case 5: v = vld4_lane_u8((const uint8_t*)(px+4), v, 4);  // fall through
-            case 4: v = vld4_lane_u8((const uint8_t*)(px+3), v, 3);  // fall through
-            case 3: v = vld4_lane_u8((const uint8_t*)(px+2), v, 2);  // fall through
-            case 2: v = vld4_lane_u8((const uint8_t*)(px+1), v, 1);
-        }
-        return v;
-    }
-
-    void store(uint32_t* px) const { vst4_u8((uint8_t*)px, fVec); }
-    void store(uint32_t* px, int n) const {
-        SkASSERT(0 < n && n < 8);
-        switch (n) {
-            case 7: vst4_lane_u8((uint8_t*)(px+6), fVec, 6);
-            case 6: vst4_lane_u8((uint8_t*)(px+5), fVec, 5);
-            case 5: vst4_lane_u8((uint8_t*)(px+4), fVec, 4);
-            case 4: vst4_lane_u8((uint8_t*)(px+3), fVec, 3);
-            case 3: vst4_lane_u8((uint8_t*)(px+2), fVec, 2);
-            case 2: vst4_lane_u8((uint8_t*)(px+1), fVec, 1);
-            case 1: vst4_lane_u8((uint8_t*)(px+0), fVec, 0);
-        }
-    }
-
-    struct Alpha {
-        uint8x8_t fA;
-        Alpha(uint8x8_t a) : fA(a) {}
-
-        static Alpha Dup(uint8_t a) { return vdup_n_u8(a); }
-        static Alpha Load(const uint8_t* a) { return vld1_u8(a); }
-        static Alpha Load(const uint8_t* a, int n) {
-            SkASSERT(0 < n && n < 8);
-            uint8x8_t v = vld1_dup_u8(a);  // n>=1, so start all lanes with alpha 0.
-            switch (n) {
-                case 7: v = vld1_lane_u8(a+6, v, 6);  // fall through
-                case 6: v = vld1_lane_u8(a+5, v, 5);  // fall through
-                case 5: v = vld1_lane_u8(a+4, v, 4);  // fall through
-                case 4: v = vld1_lane_u8(a+3, v, 3);  // fall through
-                case 3: v = vld1_lane_u8(a+2, v, 2);  // fall through
-                case 2: v = vld1_lane_u8(a+1, v, 1);
-            }
-            return v;
-        }
-        Alpha inv() const { return vsub_u8(vdup_n_u8(255), fA); }
-    };
-
-    struct Wide {
-        uint16x8x4_t fVec;
-        Wide(uint16x8x4_t vec) : fVec(vec) {}
-
-        Wide operator+(const Wide& o) const {
-            return (uint16x8x4_t) {{
-                vaddq_u16(fVec.val[0], o.fVec.val[0]),
-                vaddq_u16(fVec.val[1], o.fVec.val[1]),
-                vaddq_u16(fVec.val[2], o.fVec.val[2]),
-                vaddq_u16(fVec.val[3], o.fVec.val[3]),
-            }};
-        }
-        Wide operator-(const Wide& o) const {
-            return (uint16x8x4_t) {{
-                vsubq_u16(fVec.val[0], o.fVec.val[0]),
-                vsubq_u16(fVec.val[1], o.fVec.val[1]),
-                vsubq_u16(fVec.val[2], o.fVec.val[2]),
-                vsubq_u16(fVec.val[3], o.fVec.val[3]),
-            }};
-        }
-        Wide operator<<(int bits) const {
-        #if defined(SK_DEBUG)
-            return (uint16x8x4_t) {{
-                shift_slow(fVec.val[0], -bits),
-                shift_slow(fVec.val[1], -bits),
-                shift_slow(fVec.val[2], -bits),
-                shift_slow(fVec.val[3], -bits),
-            }};
-        #else
-            return (uint16x8x4_t) {{
-                vshlq_n_u16(fVec.val[0], bits),
-                vshlq_n_u16(fVec.val[1], bits),
-                vshlq_n_u16(fVec.val[2], bits),
-                vshlq_n_u16(fVec.val[3], bits),
-            }};
-        #endif
-        }
-        Wide operator>>(int bits) const {
-        #if defined(SK_DEBUG)
-            return (uint16x8x4_t) {{
-                shift_slow(fVec.val[0], bits),
-                shift_slow(fVec.val[1], bits),
-                shift_slow(fVec.val[2], bits),
-                shift_slow(fVec.val[3], bits),
-            }};
-        #else
-            return (uint16x8x4_t) {{
-                vshrq_n_u16(fVec.val[0], bits),
-                vshrq_n_u16(fVec.val[1], bits),
-                vshrq_n_u16(fVec.val[2], bits),
-                vshrq_n_u16(fVec.val[3], bits),
-            }};
-        #endif
-        }
-
-        // v >> bits, for bits in [-15, 16].
-        static uint16x8_t shift_slow(uint16x8_t v, int bits) {
-            SkASSERT(bits >= -16 && bits <= 16);
-            switch (bits) {
-            #define L(n) case -n: return vshlq_n_u16(v, n);
-            #define R(n) case  n: return vshrq_n_u16(v, n);
-                      L(15) L(14) L(13) L(10) L(9) L(8) L(7) L(6) L(5) L(4) L(3) L(2) L(1)
-                R(16) R(15) R(14) R(13) R(10) R(9) R(8) R(7) R(6) R(5) R(4) R(3) R(2) R(1)
-            #undef L
-            #undef R
-            }
-            return v;
-        }
-
-        SkPx_neon addNarrowHi(const SkPx_neon& o) const {
-            return (uint8x8x4_t) {{
-                vshrn_n_u16(vaddw_u8(fVec.val[0], o.fVec.val[0]), 8),
-                vshrn_n_u16(vaddw_u8(fVec.val[1], o.fVec.val[1]), 8),
-                vshrn_n_u16(vaddw_u8(fVec.val[2], o.fVec.val[2]), 8),
-                vshrn_n_u16(vaddw_u8(fVec.val[3], o.fVec.val[3]), 8),
-            }};
-        }
-    };
-
-    Alpha alpha() const { return fVec.val[3]; }
-
-    Wide widenLo() const {
-        return (uint16x8x4_t) {{
-            vmovl_u8(fVec.val[0]),
-            vmovl_u8(fVec.val[1]),
-            vmovl_u8(fVec.val[2]),
-            vmovl_u8(fVec.val[3]),
-        }};
-    }
-    // TODO: these two can probably be done faster.
-    Wide widenHi() const { return this->widenLo() << 8; }
-    Wide widenLoHi() const { return this->widenLo() + this->widenHi(); }
-
-    SkPx_neon operator+(const SkPx_neon& o) const {
-        return (uint8x8x4_t) {{
-            vadd_u8(fVec.val[0], o.fVec.val[0]),
-            vadd_u8(fVec.val[1], o.fVec.val[1]),
-            vadd_u8(fVec.val[2], o.fVec.val[2]),
-            vadd_u8(fVec.val[3], o.fVec.val[3]),
-        }};
-    }
-    SkPx_neon operator-(const SkPx_neon& o) const {
-        return (uint8x8x4_t) {{
-            vsub_u8(fVec.val[0], o.fVec.val[0]),
-            vsub_u8(fVec.val[1], o.fVec.val[1]),
-            vsub_u8(fVec.val[2], o.fVec.val[2]),
-            vsub_u8(fVec.val[3], o.fVec.val[3]),
-        }};
-    }
-    SkPx_neon saturatedAdd(const SkPx_neon& o) const {
-        return (uint8x8x4_t) {{
-            vqadd_u8(fVec.val[0], o.fVec.val[0]),
-            vqadd_u8(fVec.val[1], o.fVec.val[1]),
-            vqadd_u8(fVec.val[2], o.fVec.val[2]),
-            vqadd_u8(fVec.val[3], o.fVec.val[3]),
-        }};
-    }
-
-    Wide operator*(const Alpha& a) const {
-        return (uint16x8x4_t) {{
-            vmull_u8(fVec.val[0], a.fA),
-            vmull_u8(fVec.val[1], a.fA),
-            vmull_u8(fVec.val[2], a.fA),
-            vmull_u8(fVec.val[3], a.fA),
-        }};
-    }
-    SkPx_neon approxMulDiv255(const Alpha& a) const {
-        return (*this * a).addNarrowHi(*this);
-    }
-
-    SkPx_neon addAlpha(const Alpha& a) const {
-        return (uint8x8x4_t) {{
-            fVec.val[0],
-            fVec.val[1],
-            fVec.val[2],
-            vadd_u8(fVec.val[3], a.fA),
-        }};
-    }
-};
-typedef SkPx_neon SkPx;
-
-#endif//SkPx_neon_DEFINED