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resize
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Optimize bound checks. 

Optimizing the bound checks resulted in an overall 14% increase in
conversion performance.
This commit is contained in:
Charlie Vieth 2015-03-15 17:44:39 -04:00
parent b09281bd36
commit d8255b0421
2 changed files with 30 additions and 30 deletions
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42
converter.go
View File

@ -20,24 +20,24 @@ import "image"
// Keep value in [0,255] range.
func clampUint8(in int32) uint8 {
if in < 0 {
return 0
if uint32(in) < 256 {
return uint8(in)
}
if in > 255 {
return 255
}
return uint8(in)
return 0
}
// Keep value in [0,65535] range.
func clampUint16(in int64) uint16 {
if in < 0 {
return 0
if uint64(in) < 65536 {
return uint16(in)
}
if in > 65535 {
return 65535
}
return uint16(in)
return 0
}
func resizeGeneric(in image.Image, out *image.RGBA64, scale float64, coeffs []int32, offset []int, filterLength int) {
@ -102,12 +102,12 @@ func resizeRGBA(in *image.RGBA, out *image.RGBA, scale float64, coeffs []int16,
if coeff != 0 {
xi := start + i
switch {
case xi < 0:
xi = 0
case uint(xi) < uint(maxX):
xi *= 4
case xi >= maxX:
xi = 4 * maxX
default:
xi *= 4
xi = 0
}
rgba[0] += int32(coeff) * int32(row[xi+0])
rgba[1] += int32(coeff) * int32(row[xi+1])
@ -142,12 +142,12 @@ func resizeRGBA64(in *image.RGBA64, out *image.RGBA64, scale float64, coeffs []i
if coeff != 0 {
xi := start + i
switch {
case xi < 0:
xi = 0
case uint(xi) < uint(maxX):
xi *= 8
case xi >= maxX:
xi = 8 * maxX
default:
xi *= 8
xi = 0
}
rgba[0] += int64(coeff) * int64(uint16(row[xi+0])<<8|uint16(row[xi+1]))
rgba[1] += int64(coeff) * int64(uint16(row[xi+2])<<8|uint16(row[xi+3]))
@ -222,12 +222,12 @@ func resizeGray16(in *image.Gray16, out *image.Gray16, scale float64, coeffs []i
if coeff != 0 {
xi := start + i
switch {
case xi < 0:
xi = 0
case uint(xi) < uint(maxX):
xi *= 2
case xi >= maxX:
xi = 2 * maxX
default:
xi *= 2
xi = 0
}
gray += int64(coeff) * int64(uint16(row[xi+0])<<8|uint16(row[xi+1]))
sum += int64(coeff)
@ -258,12 +258,12 @@ func resizeYCbCr(in *ycc, out *ycc, scale float64, coeffs []int16, offset []int,
if coeff != 0 {
xi := start + i
switch {
case xi < 0:
xi = 0
case uint(xi) < uint(maxX):
xi *= 3
case xi >= maxX:
xi = 3 * maxX
default:
xi *= 3
xi = 0
}
p[0] += int32(coeff) * int32(row[xi+0])
p[1] += int32(coeff) * int32(row[xi+1])
@ -295,12 +295,12 @@ func nearestYCbCr(in *ycc, out *ycc, scale float64, coeffs []bool, offset []int,
if coeffs[ci+i] {
xi := start + i
switch {
case xi < 0:
xi = 0
case uint(xi) < uint(maxX):
xi *= 3
case xi >= maxX:
xi = 3 * maxX
default:
xi *= 3
xi = 0
}
p[0] += float32(row[xi+0])
p[1] += float32(row[xi+1])

18
nearest.go
View File

@ -94,12 +94,12 @@ func nearestRGBA(in *image.RGBA, out *image.RGBA, scale float64, coeffs []bool,
if coeffs[ci+i] {
xi := start + i
switch {
case xi < 0:
xi = 0
case uint(xi) < uint(maxX):
xi *= 4
case xi >= maxX:
xi = 4 * maxX
default:
xi *= 4
xi = 0
}
rgba[0] += float32(row[xi+0])
rgba[1] += float32(row[xi+1])
@ -133,12 +133,12 @@ func nearestRGBA64(in *image.RGBA64, out *image.RGBA64, scale float64, coeffs []
if coeffs[ci+i] {
xi := start + i
switch {
case xi < 0:
xi = 0
case uint(xi) < uint(maxX):
xi *= 8
case xi >= maxX:
xi = 8 * maxX
default:
xi *= 8
xi = 0
}
rgba[0] += float32(uint16(row[xi+0])<<8 | uint16(row[xi+1]))
rgba[1] += float32(uint16(row[xi+2])<<8 | uint16(row[xi+3]))
@ -211,12 +211,12 @@ func nearestGray16(in *image.Gray16, out *image.Gray16, scale float64, coeffs []
if coeffs[ci+i] {
xi := start + i
switch {
case xi < 0:
xi = 0
case uint(xi) < uint(maxX):
xi *= 2
case xi >= maxX:
xi = 2 * maxX
default:
xi *= 2
xi = 0
}
gray += float32(uint16(row[xi+0])<<8 | uint16(row[xi+1]))
sum++