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sk_linear_from_srgb_math

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Looks great (imperceptibly different) but ~10% slower on both ARMv8 and x86-64.  Probably need to hide the table-or-math logic behind Sk4f/Sk8f unless we find faster math.

I do like the new look of the pipeline stages though.  A lot clearer.

BUG=skia:

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2880

CQ_INCLUDE_TRYBOTS=master.client.skia:Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Release-SKNX_NO_SIMD-Trybot

Change-Id: I44952237d56ba167445b07d4830eb8959c4d47b7
Reviewed-on: https://skia-review.googlesource.com/2880
Commit-Queue: Mike Klein <mtklein@chromium.org>
Reviewed-by: Matt Sarett <msarett@google.com>
This commit is contained in:
Mike Klein 2016-10-04 09:29:32 -04:00 committed by Skia Commit-Bot
parent ab87d7abf1
commit 418aa61fea
2 changed files with 29 additions and 68 deletions
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19
src/core/SkSRGB.h
View File

@ -62,4 +62,23 @@ static inline Sk4i sk_linear_to_srgb_noclamp(const Sk4f& x) {
return SkNx_cast<int>(f);
}
// sRGB -> linear, using math instead of table lookups, scaling better to larger SIMD vectors.
static inline Sk4f sk_linear_from_srgb_math(const Sk4i& s) {
auto x = SkNx_cast<float>(s);
const float u = 1/255.0f; // x is [0,255], so x^n needs scaling by u^n.
// Non-linear segment of sRGB curve approximated by
// l = 0.0025 + 0.6975x^2 + 0.3x^3
const float k0 = 0.0025f,
k2 = 0.6975f * u*u,
k3 = 0.3000f * u*u*u;
auto hi = k0 + (k2 + k3*x) * (x*x);
// Linear segment of sRGB curve: the normal slope, extended a little further than normal.
auto lo = x * (u/12.92f);
return (x < 14.025f).thenElse(lo, hi);
}
#endif//SkSRGB_DEFINED

78
src/opts/SkRasterPipeline_opts.h
View File

@ -244,79 +244,21 @@ namespace SK_OPTS_NS {
KERNEL_Sk4f(load_d_srgb) {
auto ptr = (const uint32_t*)ctx + x;
if (tail) {
float rs[] = {0,0,0,0},
gs[] = {0,0,0,0},
bs[] = {0,0,0,0},
as[] = {0,0,0,0};
for (size_t i = 0; i < tail; i++) {
rs[i] = sk_linear_from_srgb[(ptr[i] >> SK_R32_SHIFT) & 0xff];
gs[i] = sk_linear_from_srgb[(ptr[i] >> SK_G32_SHIFT) & 0xff];
bs[i] = sk_linear_from_srgb[(ptr[i] >> SK_B32_SHIFT) & 0xff];
as[i] = (1/255.0f) * (ptr[i] >> SK_A32_SHIFT) ;
}
dr = Sk4f::Load(rs);
dg = Sk4f::Load(gs);
db = Sk4f::Load(bs);
da = Sk4f::Load(as);
return;
}
dr = { sk_linear_from_srgb[(ptr[0] >> SK_R32_SHIFT) & 0xff],
sk_linear_from_srgb[(ptr[1] >> SK_R32_SHIFT) & 0xff],
sk_linear_from_srgb[(ptr[2] >> SK_R32_SHIFT) & 0xff],
sk_linear_from_srgb[(ptr[3] >> SK_R32_SHIFT) & 0xff] };
dg = { sk_linear_from_srgb[(ptr[0] >> SK_G32_SHIFT) & 0xff],
sk_linear_from_srgb[(ptr[1] >> SK_G32_SHIFT) & 0xff],
sk_linear_from_srgb[(ptr[2] >> SK_G32_SHIFT) & 0xff],
sk_linear_from_srgb[(ptr[3] >> SK_G32_SHIFT) & 0xff] };
db = { sk_linear_from_srgb[(ptr[0] >> SK_B32_SHIFT) & 0xff],
sk_linear_from_srgb[(ptr[1] >> SK_B32_SHIFT) & 0xff],
sk_linear_from_srgb[(ptr[2] >> SK_B32_SHIFT) & 0xff],
sk_linear_from_srgb[(ptr[3] >> SK_B32_SHIFT) & 0xff] };
da = SkNx_cast<float>(Sk4u::Load(ptr) >> SK_A32_SHIFT) * (1/255.0f);
auto px = load_tail(tail, (const int*)ptr);
dr = sk_linear_from_srgb_math((px >> SK_R32_SHIFT) & 0xff);
dg = sk_linear_from_srgb_math((px >> SK_G32_SHIFT) & 0xff);
db = sk_linear_from_srgb_math((px >> SK_B32_SHIFT) & 0xff);
da = (1/255.0f)*SkNx_cast<float>((px >> SK_A32_SHIFT) & 0xff);
}
KERNEL_Sk4f(load_s_srgb) {
auto ptr = (const uint32_t*)ctx + x;
if (tail) {
float rs[] = {0,0,0,0},
gs[] = {0,0,0,0},
bs[] = {0,0,0,0},
as[] = {0,0,0,0};
for (size_t i = 0; i < tail; i++) {
rs[i] = sk_linear_from_srgb[(ptr[i] >> SK_R32_SHIFT) & 0xff];
gs[i] = sk_linear_from_srgb[(ptr[i] >> SK_G32_SHIFT) & 0xff];
bs[i] = sk_linear_from_srgb[(ptr[i] >> SK_B32_SHIFT) & 0xff];
as[i] = (1/255.0f) * (ptr[i] >> SK_A32_SHIFT) ;
}
r = Sk4f::Load(rs);
g = Sk4f::Load(gs);
b = Sk4f::Load(bs);
a = Sk4f::Load(as);
return;
}
r = { sk_linear_from_srgb[(ptr[0] >> SK_R32_SHIFT) & 0xff],
sk_linear_from_srgb[(ptr[1] >> SK_R32_SHIFT) & 0xff],
sk_linear_from_srgb[(ptr[2] >> SK_R32_SHIFT) & 0xff],
sk_linear_from_srgb[(ptr[3] >> SK_R32_SHIFT) & 0xff] };
g = { sk_linear_from_srgb[(ptr[0] >> SK_G32_SHIFT) & 0xff],
sk_linear_from_srgb[(ptr[1] >> SK_G32_SHIFT) & 0xff],
sk_linear_from_srgb[(ptr[2] >> SK_G32_SHIFT) & 0xff],
sk_linear_from_srgb[(ptr[3] >> SK_G32_SHIFT) & 0xff] };
b = { sk_linear_from_srgb[(ptr[0] >> SK_B32_SHIFT) & 0xff],
sk_linear_from_srgb[(ptr[1] >> SK_B32_SHIFT) & 0xff],
sk_linear_from_srgb[(ptr[2] >> SK_B32_SHIFT) & 0xff],
sk_linear_from_srgb[(ptr[3] >> SK_B32_SHIFT) & 0xff] };
a = SkNx_cast<float>(Sk4u::Load(ptr) >> SK_A32_SHIFT) * (1/255.0f);
auto px = load_tail(tail, (const int*)ptr);
r = sk_linear_from_srgb_math((px >> SK_R32_SHIFT) & 0xff);
g = sk_linear_from_srgb_math((px >> SK_G32_SHIFT) & 0xff);
b = sk_linear_from_srgb_math((px >> SK_B32_SHIFT) & 0xff);
a = (1/255.0f)*SkNx_cast<float>((px >> SK_A32_SHIFT) & 0xff);
}
KERNEL_Sk4f(store_srgb) {