Inline performance-critical methods on SkAlphaRuns

src/core/SkAntiRun.h

Index: src/core/SkAntiRun.h
diff --git a/src/core/SkAntiRun.h b/src/core/SkAntiRun.h
index 123972692eb6cdad8fe762d0fe65e13170f3af4d..9a0003935f71ac0777549cc68ed5f5bae8b82197 100644
--- a/src/core/SkAntiRun.h
+++ b/src/core/SkAntiRun.h
@@ -45,8 +45,63 @@ public:
      *  assuming we're on the same scanline. If the caller is switching
      *  scanlines, then offsetX should be 0 when this is called.
      */
-    int add(int x, U8CPU startAlpha, int middleCount, U8CPU stopAlpha,
-            U8CPU maxValue, int offsetX);
+    SK_ALWAYS_INLINE int add(int x, U8CPU startAlpha, int middleCount, U8CPU stopAlpha,
+                             U8CPU maxValue, int offsetX) {
+        SkASSERT(middleCount >= 0);
+        SkASSERT(x >= 0 && x + (startAlpha != 0) + middleCount + (stopAlpha != 0) <= fWidth);
+
+        SkASSERT(fRuns[offsetX] >= 0);
+
+        int16_t*    runs = fRuns + offsetX;
+        uint8_t*    alpha = fAlpha + offsetX;
+        uint8_t*    lastAlpha = alpha;
+        x -= offsetX;
+
+        if (startAlpha) {
+            SkAlphaRuns::Break(runs, alpha, x, 1);
+            /*  I should be able to just add alpha[x] + startAlpha.
+                However, if the trailing edge of the previous span and the leading
+                edge of the current span round to the same super-sampled x value,
+                I might overflow to 256 with this add, hence the funny subtract (crud).
+            */
+            unsigned tmp = alpha[x] + startAlpha;
+            SkASSERT(tmp <= 256);
+            alpha[x] = SkToU8(tmp - (tmp >> 8));    // was (tmp >> 7), but that seems wrong if we're trying to catch 256
+
+            runs += x + 1;
+            alpha += x + 1;
+            x = 0;
+            lastAlpha += x; // we don't want the +1
+            SkDEBUGCODE(this->validate();)
+        }
+
+        if (middleCount) {
+            SkAlphaRuns::Break(runs, alpha, x, middleCount);
+            alpha += x;
+            runs += x;
+            x = 0;
+            do {
+                alpha[0] = SkToU8(alpha[0] + maxValue);
+                int n = runs[0];
+                SkASSERT(n <= middleCount);
+                alpha += n;
+                runs += n;
+                middleCount -= n;
+            } while (middleCount > 0);
+            SkDEBUGCODE(this->validate();)
+            lastAlpha = alpha;
+        }
+
+        if (stopAlpha) {
+            SkAlphaRuns::Break(runs, alpha, x, 1);
+            alpha += x;
+            alpha[0] = SkToU8(alpha[0] + stopAlpha);
+            SkDEBUGCODE(this->validate();)
+            lastAlpha = alpha;
+        }
+
+        return SkToS32(lastAlpha - fAlpha);  // new offsetX
+    }
 
     SkDEBUGCODE(void assertValid(int y, int maxStep) const;)
     SkDEBUGCODE(void dump() const;)
@@ -59,7 +114,52 @@ public:
      * Allows add() to sum another run to some of the new sub-runs.
      *   i.e. adding ..CCCCC. would produce AADDEEEB, rle as A2D2E3B1.
      */
-    static void Break(int16_t runs[], uint8_t alpha[], int x, int count);
+    static void Break(int16_t runs[], uint8_t alpha[], int x, int count) {
+        SkASSERT(count > 0 && x >= 0);
+
+        //  SkAlphaRuns::BreakAt(runs, alpha, x);
+        //  SkAlphaRuns::BreakAt(&runs[x], &alpha[x], count);
+
+        int16_t* next_runs = runs + x;
+        uint8_t*  next_alpha = alpha + x;
+
+        while (x > 0) {
+            int n = runs[0];
+            SkASSERT(n > 0);
+
+            if (x < n) {
+                alpha[x] = alpha[0];
+                runs[0] = SkToS16(x);
+                runs[x] = SkToS16(n - x);
+                break;
+            }
+            runs += n;
+            alpha += n;
+            x -= n;
+        }
+
+        runs = next_runs;
+        alpha = next_alpha;
+        x = count;
+
+        for (;;) {
+            int n = runs[0];
+            SkASSERT(n > 0);
+
+            if (x < n) {
+                alpha[x] = alpha[0];
+                runs[0] = SkToS16(x);
+                runs[x] = SkToS16(n - x);
+                break;
+            }
+            x -= n;
+            if (x <= 0) {
+                break;
+            }
+            runs += n;
+            alpha += n;
+        }
+    }
 
     /**
      * Cut (at offset x in the buffer) a run into two shorter runs with