MyouProject/pixie
2
0
Fork 0
Code Issues Pull requests Actions Packages Projects Releases Wiki Activity

simd toAlphy

Browse source
This commit is contained in:
Ryan Oldenburg 2021-01-19 18:57:34 -06:00
parent 8e2b4dc386
commit 47cb962e23
1 changed files with 36 additions and 1 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

37
src/pixie/images.nim
View file

@ -200,10 +200,45 @@ proc fromAlphy*(c: Color): Color =
proc toAlphy*(image: Image) =
## Converts an image to premultiplied alpha from straight.
for c in image.data.mitems:
var i: int
when defined(amd64):
# When supported, SIMD convert as much as possible
let
alphaMask = mm_set1_epi32(cast[int32](0xff000000))
alphaMaskComp = mm_set1_epi32(0x00ffffff)
oddMask = mm_set1_epi16(cast[int16](0xff00))
div255 = mm_set1_epi16(cast[int16](0x8081))
for j in countup(i, image.data.len - 4, 4):
var
color = mm_load_si128(image.data[j].addr)
alpha = mm_and_si128(color, alphaMask)
alpha = mm_or_si128(alpha, mm_srli_epi32(alpha, 16))
var
colorEven = mm_slli_epi16(color, 8)
colorOdd = mm_and_si128(color, oddMask)
colorEven = mm_mulhi_epu16(colorEven, alpha)
colorOdd = mm_mulhi_epu16(colorOdd, alpha)
colorEven = mm_srli_epi16(mm_mulhi_epu16(colorEven, div255), 7)
colorOdd = mm_srli_epi16(mm_mulhi_epu16(colorOdd, div255), 7)
color = mm_or_si128(colorEven, mm_slli_epi16(colorOdd, 8))
color = mm_or_si128(
mm_and_si128(alpha, alphaMask), mm_and_si128(color, alphaMaskComp)
)
mm_store_si128(image.data[j].addr, color)
i += 4
# Convert whatever is left
for j in i ..< image.data.len:
var c = image.data[j]
c.r = ((c.r.uint32 * c.a.uint32) div 255).uint8
c.g = ((c.g.uint32 * c.a.uint32) div 255).uint8
c.b = ((c.b.uint32 * c.a.uint32) div 255).uint8
image.data[j] = c
proc fromAlphy*(image: Image) =
## Converts an image to from premultiplied alpha to straight.