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Speed up set-argb-pixels by using unsafe operations.

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Presumably, values shouldn't ever wrap and the bytestring is already
assured to be long enough, so using safe operations isn't strictly
necessary. This dangerous improvement yields speedup factor of ~1.86.
This commit is contained in:
Michael Wilber 2012-12-16 10:19:33 -07:00 committed by Matthew Flatt
parent 6308f3011d
commit e6c1e73452
1 changed files with 23 additions and 17 deletions
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40
collects/racket/draw/private/bitmap.rkt
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@ -728,33 +728,39 @@
(let ([row (* j row-width)]
[p (* 4 (* dj w))])
(for ([i (in-range x w2)])
(let* ([4i (* 4 i)]
[pi (+ p (* 4 (- i x)))]
[ri (+ row 4i)])
(let* ([4i (unsafe-fx* 4 i)]
[pi (unsafe-fx+ p (unsafe-fx* 4 (unsafe-fx- i x)))]
[ri (unsafe-fx+ row 4i)])
(if b&w-local?
(let ([v (if (and (= (bytes-ref bstr (+ pi 1)) 255)
(= (bytes-ref bstr (+ pi 2)) 255)
(= (bytes-ref bstr (+ pi 3)) 255))
(let ([v (if (and (= (unsafe-bytes-ref bstr (+ pi 1)) 255)
(= (unsafe-bytes-ref bstr (+ pi 2)) 255)
(= (unsafe-bytes-ref bstr (+ pi 3)) 255))
255
0)])
(bytes-set! data (+ ri A) (- 255 v))
(bytes-set! data (+ ri 1) v)
(bytes-set! data (+ ri 2) v)
(bytes-set! data (+ ri B) v))
(unsafe-bytes-set! data (unsafe-fx+ ri A) (- 255 v))
(unsafe-bytes-set! data (unsafe-fx+ ri 1) v)
(unsafe-bytes-set! data (unsafe-fx+ ri 2) v)
(unsafe-bytes-set! data (unsafe-fx+ ri B) v))
(if alpha-channel-local?
(let ([a (bytes-ref bstr pi)]
[pm (lambda (a v)
(if m
(unsafe-bytes-ref m (fx+ (fx* a 256) v))
(min a v)))])
(bytes-set! data (+ ri A) a)
(bytes-set! data (+ ri R) (pm a (bytes-ref bstr (+ pi 1))))
(bytes-set! data (+ ri G) (pm a (bytes-ref bstr (+ pi 2))))
(bytes-set! data (+ ri B) (pm a (bytes-ref bstr (+ pi 3)))))
(unsafe-bytes-set! data (unsafe-fx+ ri A) a)
(unsafe-bytes-set! data (unsafe-fx+ ri R)
(pm a (unsafe-bytes-ref bstr (unsafe-fx+ pi 1))))
(unsafe-bytes-set! data (unsafe-fx+ ri G)
(pm a (unsafe-bytes-ref bstr (unsafe-fx+ pi 2))))
(unsafe-bytes-set! data (unsafe-fx+ ri B)
(pm a (unsafe-bytes-ref bstr (unsafe-fx+ pi 3)))))
(begin
(bytes-set! data (+ ri R) (bytes-ref bstr (+ pi 1)))
(bytes-set! data (+ ri G) (bytes-ref bstr (+ pi 2)))
(bytes-set! data (+ ri B) (bytes-ref bstr (+ pi 3))))))))))))
(unsafe-bytes-set! data (unsafe-fx+ ri R)
(unsafe-bytes-ref bstr (unsafe-fx+ pi 1)))
(unsafe-bytes-set! data (unsafe-fx+ ri G)
(unsafe-bytes-ref bstr (unsafe-fx+ pi 2)))
(unsafe-bytes-set! data (unsafe-fx+ ri B)
(unsafe-bytes-ref bstr (unsafe-fx+ pi 3))))))))))))
(cairo_surface_mark_dirty s)))
(cond
[(and set-alpha?