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author | Janne Grunau <janne-libav@jannau.net> | 2014-02-13 12:27:17 +0100 |
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committer | Janne Grunau <janne-libav@jannau.net> | 2014-02-14 18:34:04 +0100 |
commit | 98fdfa99704f1cfef3d3a26c580b92749b6b64cb (patch) | |
tree | 57d3ad6e86479a6d9b32d0fa8fd91f424f73f859 /libavcodec/ppc | |
parent | 3fbad00714698f59c6326edfcc63db87f525e7c0 (diff) | |
download | ffmpeg-streaming-98fdfa99704f1cfef3d3a26c580b92749b6b64cb.zip ffmpeg-streaming-98fdfa99704f1cfef3d3a26c580b92749b6b64cb.tar.gz |
ppc: reduce overreads when loading 8 pixels in altivec dsp functions
Altivec can only load naturally aligned vectors. To handle possibly
unaligned data a second vector is loaded from an offset of the original
location and the data is recovered through a vector permutation.
Overreads are minimal if the offset for second load points to the last
element of data. This is 7 for loading eight 8-bit pixels and overreads
are reduced from 16 bytes to 8 bytes if the pixels are 64-bit aligned.
For unaligned pixels the overread is reduced from 23 bytes to 15 bytes
in the worst case.
Diffstat (limited to 'libavcodec/ppc')
-rw-r--r-- | libavcodec/ppc/dsputil_altivec.c | 20 |
1 files changed, 10 insertions, 10 deletions
diff --git a/libavcodec/ppc/dsputil_altivec.c b/libavcodec/ppc/dsputil_altivec.c index f90ec74..6f6c5f3 100644 --- a/libavcodec/ppc/dsputil_altivec.c +++ b/libavcodec/ppc/dsputil_altivec.c @@ -285,10 +285,10 @@ static int sad8_altivec(void *v, uint8_t *pix1, uint8_t *pix2, int line_size, in /* Read potentially unaligned pixels into t1 and t2 Since we're reading 16 pixels, and actually only want 8, mask out the last 8 pixels. The 0s don't change the sum. */ - vector unsigned char pix1l = vec_ld( 0, pix1); - vector unsigned char pix1r = vec_ld(15, pix1); - vector unsigned char pix2l = vec_ld( 0, pix2); - vector unsigned char pix2r = vec_ld(15, pix2); + vector unsigned char pix1l = vec_ld(0, pix1); + vector unsigned char pix1r = vec_ld(7, pix1); + vector unsigned char pix2l = vec_ld(0, pix2); + vector unsigned char pix2r = vec_ld(7, pix2); t1 = vec_and(vec_perm(pix1l, pix1r, perm1), permclear); t2 = vec_and(vec_perm(pix2l, pix2r, perm2), permclear); @@ -367,10 +367,10 @@ static int sse8_altivec(void *v, uint8_t *pix1, uint8_t *pix2, int line_size, in /* Read potentially unaligned pixels into t1 and t2 Since we're reading 16 pixels, and actually only want 8, mask out the last 8 pixels. The 0s don't change the sum. */ - vector unsigned char pix1l = vec_ld( 0, pix1); - vector unsigned char pix1r = vec_ld(15, pix1); - vector unsigned char pix2l = vec_ld( 0, pix2); - vector unsigned char pix2r = vec_ld(15, pix2); + vector unsigned char pix1l = vec_ld(0, pix1); + vector unsigned char pix1r = vec_ld(7, pix1); + vector unsigned char pix2l = vec_ld(0, pix2); + vector unsigned char pix2r = vec_ld(7, pix2); t1 = vec_and(vec_perm(pix1l, pix1r, perm1), permclear); t2 = vec_and(vec_perm(pix2l, pix2r, perm2), permclear); @@ -489,8 +489,8 @@ static void get_pixels_altivec(int16_t *restrict block, const uint8_t *pixels, i // Read potentially unaligned pixels. // We're reading 16 pixels, and actually only want 8, // but we simply ignore the extras. - vector unsigned char pixl = vec_ld( 0, pixels); - vector unsigned char pixr = vec_ld(15, pixels); + vector unsigned char pixl = vec_ld(0, pixels); + vector unsigned char pixr = vec_ld(7, pixels); bytes = vec_perm(pixl, pixr, perm); // convert the bytes into shorts |