1#ifndef SkBitmapProcState_utils_DEFINED
2#define SkBitmapProcState_utils_DEFINED
3
4// Helper to ensure that when we shift down, we do it w/o sign-extension
5// so the caller doesn't have to manually mask off the top 16 bits
6//
7static unsigned SK_USHIFT16(unsigned x) {
8    return x >> 16;
9}
10
11/*
12 *  The decal_ functions require that
13 *  1. dx > 0
14 *  2. [fx, fx+dx, fx+2dx, fx+3dx, ... fx+(count-1)dx] are all <= maxX
15 *
16 *  In addition, we use SkFractionalInt to keep more fractional precision than
17 *  just SkFixed, so we will abort the decal_ call if dx is very small, since
18 *  the decal_ function just operates on SkFixed. If that were changed, we could
19 *  skip the very_small test here.
20 */
21static inline bool can_truncate_to_fixed_for_decal(SkFractionalInt frX,
22                                                   SkFractionalInt frDx,
23                                                   int count, unsigned max) {
24    SkFixed dx = SkFractionalIntToFixed(frDx);
25
26    // if decal_ kept SkFractionalInt precision, this would just be dx <= 0
27    // I just made up the 1/256. Just don't want to perceive accumulated error
28    // if we truncate frDx and lose its low bits.
29    if (dx <= SK_Fixed1 / 256) {
30        return false;
31    }
32
33    // We cast to unsigned so we don't have to check for negative values, which
34    // will now appear as very large positive values, and thus fail our test!
35    SkFixed fx = SkFractionalIntToFixed(frX);
36    return (unsigned)SkFixedFloorToInt(fx) <= max &&
37           (unsigned)SkFixedFloorToInt(fx + dx * (count - 1)) < max;
38}
39
40#endif /* #ifndef SkBitmapProcState_utils_DEFINED */
41