Some single-frame GIF images have a canvas larger than the frame rectangle. For
such images, we retain the ANMF, ANIM and VP8X chunks in the output WebP file.
This ensures that the full canvas width/height and frame offsets are retained.
Change-Id: I3ebae4893f953984de4072fda0938411de787a29
if a thread was still doing work when End() was called there'd be a race
on worker->status_. in these cases, however, the specific value is
meaningless as it would be >= OK and the thread would have been shut
down properly, but we'll check 'impl_' instead to avoid any potential
TSan/DRD reports.
Change-Id: Ib93cbc226a099f07761f7bad765549dffb8054b1
defines HAVE_BUILTIN_BSWAP16/32/64
updated endian_inl.h to have a non-configure fallback for gcc and clang
BSwap16() now uses __builtin_bswap16 if available
Change-Id: Ia04ee07b39303c4b247df96d84f298fb8a81f389
also reduce the load size from 64 to 32 bits as the top 32 bits are
being shifted away in the operation.
the change is neutral speed-wise on x86_64 as is the change in load size
on x86, but it gives a slight improvement on 32-bit arm.
x86 is improved ~13%, 32-bit arm ~3.7%
aarch64 is untested but will likely benefit as well.
Change-Id: Ibcb02a70f46f2651105d7ab571afe352673bef48
forces aligned memory reads (via memcpy) in the VP8 bit reader, useful
for platforms that don't support unaligned loads.
Change-Id: Ifa44a9a1677fbdc6a929520f9340b7e3fcbd6692
this defines WORDS_BIGENDIAN, replacing uses of
__BIG_ENDIAN__/__BYTE_ORDER__ with it
+ fixes lossless BGRA output with big-endian toolchains
that do not define __BIG_ENDIAN__ (codesourcery mips gcc)
Change-Id: Ieaccd623292d235343b5e34b7a720fc251c432d7
moves the following to this header:
- htole*() definitions from bit_writer.c
- __BIG_ENDIAN__ fallback define from bit_reader_inl.h
Change-Id: I7fff59543f08a70bf8f9ddac849b72ed290471b1
(typecast uint32 pointer to uint64).
The proposed change is little (0.05%) slower but avoids uint32 to uint64
pointer conversion.
Change-Id: I6b8828077ea1324fabd04bfa7e7439e324776250
previously, the final canvas size was adjusted tightly from the
animation frames. Now, it can be specified separately (to be larger, in particular).
calling WebPMuxSetCanvasSize(mux, 0, 0) triggers the 'adjust tightly' behaviour.
This can be useful after calling WebPMuxCreate() if further image addition
is expected.
-> Fixed gif2webp accordingly.
also: made WebPMuxAssemble() more robust by systematically zero-ing WebPData.
Change-Id: Ib4f7eac372cf9dbf6e25cd686a77960e386a0b7f
this will remove a warning about the shift amount not being
an immediate (=constant).
Change-Id: Ie9a00fefdb9a07ec8994fb113f24234518bc878a
Also: fix the NULL sharpen argument mismatch.
mostly to balance the use of bswap64, some gcc platforms are already
interpreting the default case the same
Change-Id: Icf860f55b3f16bea349a7d721e6d6abeeb4e5cf3
Another store to load forward block was detected coming from the function
FTransform.
FTransform save the output data 4 times 8 bytes each. when this data is
later being loaded by the QuantizeBlock function in one chunk of 16 bytes
that caused a store to load forward block.
The fix was done in the FTransform function where each two consecutive 8 bytes
were merged into one 16 bytes register and saved into the memory.
This fix gives ~21% function level gain and 1.6% user level gain.
Change-Id: Idc27c307d5083f3ebe206d3ca19059e5bd465992
ChunkVerifyAndAssign() expects to have at least 8 bytes to work with,
but was only checking for the presence of 4.
Change-Id: I8456b15d872de24a90c1e8fbfba463391ced5c7f
new options:
dwebp -alpha_dither
vwebp -noalphadither
When the source was marked as quantized, we use a threshold-averaging
filter to smooth the decoded alpha plane.
Note: this option forces the decoding of alpha data in one pass, and
might slow the decoding a bit.
The new field in WebPDecoderOptions struct is 'alpha_dithering_strength'
(0 by default, means: off). Max strength value is '100'.
Change-Id: I218e21af96360d4781587fede95f8ea4e2b7287a
Sometimes, the error-code was not set correctly.
We now return OUT_OF_MEMORY everytimes it's appropriate
(tested using MALLOC_FAIL_AT mechanism)
Took the opportunity to clean-up the code and dust the error
code returned (some were erroneously set to INVALID_CONFIGURATION)
Change-Id: I56f7331e2447557b3dd038e245daace4fc82214c
only 1 of <lib>_CPPFLAGS and AM_CPPFLAGS is used, with the former
getting precedence when it's defined. configure's DEFAULT_INCLUDES is
covering what's necessary given the include paths are all source
relative.
Change-Id: I7d14076acd266b28a88a3d92bcc3d7165284d5f3
this change has the side-effect of using directory names in the
include, silencing a lint warning.
Change-Id: Ib91cf63a90534e32fadfa5c2372bfdb29f854d02
if res->first = 1, coeffs[0]=0 because of quant.c:749 and line
added at quant.c:744
So, no need for the extra case.
Going forward, TrellisQuantizeBlock() should also be calling
a variant of VP8SetResidualCoeffs() to set the 'last' field.
also: fixes a warning for win64
+ slight speed-up
Change-Id: Ib24b611f7396d24aeb5b56dc74d5c39160f048f0
+ add a WEBP_HAVE_SSE2 to dsp.h
not all 32-bit toolchain configurations will have sse2 enabled by
default
Change-Id: I7c675e511581f93cf55c79f960fa7efa2df4987e
this is used to set WEBP_USE_AVX2 in files where the build flag won't be
used, i.e., dsp/enc.c, which enables VP8EncDspInitAVX2() to be called
Change-Id: I362f4ba39ca40d3e07a081292d5f743c649d9d7f
* remove LEFT/RIGHT_JUSTIFY distinction. It's all RIGHT_JUSTIFY now.
* simplify VP8GetSigned(), and add some masking branch-less code. Much
faster on ARM (~13% speed-up). 8% on x86-64, 5% on MacBook.
* split critical implementation into separate bit_reader_inl.h file that
is only included where needed (vp8.c / tree.c / bit_reader.c)
* bumped BITS value from 16 to 24 for x86-32b too, since it's a bit faster.
Change-Id: If41ca1da3e5c3dadacf2379d1ba419b151e7fce8
Extract loop invariant and avoid storing/loading samples
if they can be re-used. This is particularly interesting when
a transpose is involved (HFilter16i).
Change-Id: I93274620f6da220a35025ff8708ff0c9ee8c4139
The luminance needs to be pre- and post- multiplied by
the alpha value in case of rescaling, for proper averaging.
Also:
- removed util/alpha_processing and moved it to dsp/
- removed WebPInitPremultiply() which was mostly useless
and merged it with the new function WebPInitAlphaProcessing()
Change-Id: If089cefd4ec53f6880a791c476fb1c7f7c5a8e60
gcc was generating very complex code, one for each case of br->len_ values!
also, pretty-fy the mask constants
Change-Id: If62b1e8266f3fe5334517305113038d2ea8a6b42
VP8EncDspInitAVX2 is included in sse2 builds for now, later a configure
flag should be added to avoid the stub when avx2 is unavailable/disabled
Change-Id: I6127b687c273f46f41652aaf8e3b86ae3cfb8108
Sometimes, we can write 18bit or more at time, and it would
overflow the 32bit accumulator.
Also clarified the num-bits limitations (and exposed
VP8L_MAX_NUM_BIT_READ in bit_reader.h)
fixes http://code.google.com/p/webp/issues/detail?id=200
Seems a bit faster (use of local fields for bits_ / used_)
also: added the __QNX__ bswap while at it.
Change-Id: I876db93a931db15b083cf1d838c70105effa7167
* remove some sign-bit flipping
* turn some macro into inline functions
* fix some 'const' in signatures
* clarify the int8/uint8 usage
Change-Id: Ib04459ac34cb280c57579c5d79a5efd2f8d5e99d
also changed the token-page layout a little bit to remove
a not-needed field.
This reduces the number of malloc()/free() calls substantially
with minimal increase in memory consumption (~2%).
For the tail of large sources, the number of malloc calls goes
typically from ~10000 to ~100 (e.g.: bryce_big.jpg: 22711 -> 105)
Change-Id: Ib847f41e618ed8c303d26b76da982fbc48de45b9
MALLOC_FAIL_AT flag can be used to set-up a pre-determined failure
point during malloc calls. The counter value is retrieved using
getenv().
Example usage: export MALLOC_FAIL_AT=37 && cwebp input.png
will make 'cwebp' report a memory allocation error the 37th time
malloc() or calloc() is called.
MALLOC_MEM_LIMIT can be used similarly to prevent allocating more
than a given amount of memory. This is usually less convenient to
use than MALLOC_FAIL_AT since one has to know in advance the typical
memory size allocated.
Both these flags are meant to be used for debugging only!
Also: added a 'total_mem_allocated' to record the overall memory allocated
Change-Id: I9d408095ee7d76acba0f3a31b1276fc36478720a
Non-photo source produce far less literal reference and their
buffer is usually much smaller than the picture size if its compresses
well. Hence, use a block-base allocation (and recycling) to avoid
pre-allocating a buffer with maximal size.
This can reduce memory consumption up to 50% for non-photographic
content. Encode speed is also a little better (1-2%)
Change-Id: Icbc229e1e5a08976348e600c8906beaa26954a11
This change reduces the number of calls to WebPSafeMalloc from 200 to
100. The overall memory consumption is down 3% for Lenna image.
Change-Id: I1b351a1f61abf2634c035ef1ccb34050b7876bdd
Some tracing code is activated by PRINT_MEM_INFO flag.
For debugging only! (not thread-safe, and slow).
Change-Id: I282c623c960f97d474a35b600981b761ef89ace9
the unique instance of VP8LHashChain (1MB size corresponding to hash_to_first_index_)
is now wholy part of VP8LEncoder, instead of maintaining the pointer to VP8LHashChain
in the encoder.
Change-Id: Ib6fe52019fdd211fbbc78dc0ba731a4af0728677
We use automatic int->uint64_t promotion where applicable.
(uint64_t should be kept only for overflow checking and memory alloc).
Change-Id: I1f41b0f73e2e6380e7d65cc15c1f730696862125
The predictors based on Average2 are tad slower.
Following is the performance data for these predictors normalized to
number of instruction cycles (as per valgrind) per operation:
- Predictor6 & Predictor7 now takes 15 instruction cycles compared to 11
instruction cycles for the C version.
- Predictor8 & Predictor9 now takes 15 instruction cycles compared to 12
instruction cycles for the C version.
The predictors based on Average4 is faster and Average3 is tad slower:
- Predictor10 (Average4) now takes 23 instruction cycles compared to 25
instruction cycles for the C version.
- Predictor5 (Average3) now takes 20 instruction cycles compared to 18
instruction cycles for the C version.
Maybe SSE2 version of Average2 can be improved further. Otherwise, we can
remove the SSE2 version and always fallback to the C version.
Change-Id: I388b2871919985bc28faaad37c1d4beeb20ba029
* merged the two HistogramAdd/AddEval() into a single call
(with detection of special case when b==out)
* added a SSE2 variant
* harmonize the histogram type to 'uint32_t' instead
of just 'int'. This has a lot of ripples on signatures.
* 1-2% faster
Change-Id: I10299ff300f36cdbca5a560df1ae4d4df149d306
move simple loop filter defines closer to their use and LOAD* to a
location common with the intrinsics
Change-Id: Iaec506d27bbc9a01be20936e30b68a4b0e690ee3
the complex loop filter has no inline equivalent; the simple loop filter
remains conditional on USE_INTRINSICS: it's left undefined for now.
Change-Id: I4f258e10458df53a7a1819707c8f46b450e9d9d2
CollectHistogram / SSE* / QuantizeBlock have no inline equivalents,
enable them where possible and use USE_INTRINSICS to control borderline
cases: it's left undefined for now.
Change-Id: I62235bc4ddb8aa0769d1ce18a90e0d7da1e18155
using this in Load4x16 was slightly slower and didn't help mitigate any
of the remaining build issues with 4.6.x.
Change-Id: Idabfe1b528842a514d14a85f4cefeb90abe08e51
Reduce calls to Malloc (WebPSafeMalloc/WebPSafeCalloc) for:
- Building HashChain data-structure used in creating the backward references.
- Creating Backward references for LZ77 or RLE coding.
- Creating Huffman tree for encoding the image.
For the above mentioned code-paths, allocate memory once and re-use it
subsequently.
Reduce the foorprint of VP8LHistogram struct by changing the Struct
field 'literal_' from an array of constant size to dynamically allocated
buffer based on the input parameter cache_bits.
Initialize BitWriter buffer corresponding to 16bpp (2*W*H).
There are some hard-files that are compressed at 12 bpp or more. The
realloc is costly and can be avoided for most of the WebP lossless
images by allocating some extra memory at the encoder initializaiton.
Change-Id: I1ea8cf60df727b8eb41547901f376c9a585e6095
HuffmanCost and HuffmanCostCombined optimized and added
'const' to some variables from ExtraCost functions.
Change-Id: I28b2b357a06766bee78bdab294b5fc8c05ac120d
When remapping buffer, br->eos_ was wrongly being set to true for
certain
images.
Also, refactored the end-of-stream detection as a function.
Reported in http://crbug.com/364830
Change-Id: I716ce082ef2b505fe24246b9c14912d8e97b5d84
Some versions of compiler in debug build can't find
a register in class 'GR_REGS' while reloading 'asm'
Number of used registers is decreased in this fix.
Change-Id: I7d7b8172b8f37f1de4db3d8534a346d7a72c5065
This is to help further optimizations.
(like in https://gerrit.chromium.org/gerrit/#/c/69787/)
There's a small slowdown (~0.5% at -z 9 quality) due to
function pointer usage. Note that, for speed, it's important
to return VP8LStreaks by value, and not pass a pointer.
Change-Id: Id4167366765fb7fc5dff89c1fd75dee456737000
.set at - Indicates that macro expansions may clobber
the assembler temporary ($at or $28) register.
Some macros may not be expanded without this
and will generate an error message if noat
is in effect.
"at" also added to the clobber list.
Change-Id: I67feebbd9f2944fc7f26c28496e49e1e2348529d
avoids:
src/dsp/enc_mips32.c: In function 'ITransformOne':
src/dsp/enc_mips32.c:123:3: can't find a register in class 'GR_REGS' while reloading 'asm'
src/dsp/enc_mips32.c:123:3: 'asm' operand has impossible constraints
Change-Id: Ic469667ee572f25e502c9873c913643cf7bbe89d
apparently faster, but we might save some load/store to/from memory
once we settle for the intrinsics-based FTransform()
(also: fixed some #ifdef USE_INTRINSICS problems)
Change-Id: I426dea299cea0c64eb21c4d81a04a960e0c263c7
Functions VP8LFastLog2Slow and VP8LFastSLog2Slow
also: replaced some "% y" by "& (y-1)" in the C-version
(since y is a power-of-two)
Change-Id: I875170384e3c333812ca42d6ce7278aecabd60f0
Verified OK, but right now they don't seem faster.
So they are disabled behind a USE_INTRINSICS flag (off for now)
Change-Id: I72a1c4fa3798f98c1e034f7ca781914c36d3392c
+ reorganize the cost-evaluation code by moving some functions
to cost.h/cost.c and exposing VP8Residual
Change-Id: Id976299b5d4484e65da8bed31b3d2eb9cb4c1f7d
slightly faster than the inline asm
in practice not much faster than the C-code in a full NEON build, but
still better overall in an Android-like one that only enables NEON for
certain files.
Change-Id: I69534016186064fd92476d5eabc0f53462d53146
* inverse transform is actually slower with intrinsics + gcc-4.6,
so is left disabled for now.
With gcc-4.8, it's a bit faster than inlined assembly.
* Sum of Square error function provide a 2-3% speed up
There's enabled by default (since there's no inlined-asm equivalent)
Change-Id: I361b3f0497bc935da4cf5b35e330e379e71f498a
+ misc cosmetics
* seems 4% slower than inlined-asm with gcc-4.6
* is a tad faster (<1%) with gcc-4.8
(disabled for now)
Change-Id: Iea6cd00053a2e9c1b1ccfdad1378be26584f1095
The nice trick is to pack 8 u + 8 v samples into a single uint8x16x_t
register, and re-use the previous (luma) functions
Change-Id: Idf50ed2d6b7137ea080d603062bc9e0c66d79f38
This change gains back 1% in compression density for method=3 and 0.5% for
method=4, at the expense of 10% slower compression speed.
Change-Id: I491aa1c726def934161d4a4377e009737fbeff82
+ added some work-around gcc-4.6 to make it compile (except one function).
+ lots of revamping
All variants tested ok.
Speed-up is ~5-7%
Change-Id: I5ceda2ee5debfada090907fe3696889eb66269c3
vertical only currently, 2.5-3% faster
placed under USE_INTRINSICS as this change depends on the simple
loopfilter
improves the simple loopfilter slightly thanks to some reorganization
Change-Id: I6611441fa54228549b21ea74c013cb78d53c7155
When 4 pixels are left, they should be processed with SSE2.
Decoding is marginally faster (~0.4%).
Encoding speed: No observable difference.
Change-Id: I3cf21c07145a560ff795451e65e64faf148d5c3e
new file: lossless_neon.c
speedup is ~5%
gcc 4.6.3 seems to be doing some sub-optimal things here,
storing register on stack using 'vstmia' and such.
Looks similar to gcc.gnu.org/bugzilla/show_bug.cgi?id=51509
I've tried adding -fno-split-wide-types and it does help
the generated assembly. But the overall speed gets worse with
this flag. We should only compile lossless_neon.c with it -> urk.
Change-Id: I2ccc0929f5ef9dfb0105960e65c0b79b5f18d3b0
It's disable for now, because it crashes gcc-4.6.3 during compilation
with -O2 or -O3. It's been tested OK with -O1.
Code is still globally disabled with USE_INTRINSICS, though.
Change-Id: I3ca6cf83f3b9545ad8909556f700758b3cefa61c
disabled for now (but tested OK), thanks to the USE_INTRINSICS #define
We'll activate the code when we're on par with non-intrinsics
Change-Id: Idbfb9cb01f4c7c9f5131b270f8c11b70d0d485ff
Tune HistogramCombineBin for hard images that are larger than 1-2 Mega
pixel and represent photographic images.
This speeds up lossless encoding on 1000 image corpus by 10-12% and compression
penalty of 0.1-0.2%.
Change-Id: Ifd03b75c503b9e886098e5fe6f86be0391ca8e81
there's still some malloc/free in the external example
This is an encoder API change because of the introduction
of WebPMemoryWriterClear() for symmetry reasons.
The MemoryWriter object should probably go in examples/ instead
of being in the main lib, though.
mux_types.h stil contain some inlined free()/malloc() that are
harder to remove (we need to put them in the libwebputils lib
and make sure link is ok). Left as a TODO for now.
Also: WebPDecodeRGB*() function are still returning a pointer
that needs to be free()'d. We should call WebPSafeFree() on
these, but it means exposing the whole mechanism. TODO(later).
Change-Id: Iad2c9060f7fa6040e3ba489c8b07f4caadfab77b
expose the predictor array as function pointers instead
of each individual sub-function
+ merged Average2() into ClampedAddSubtractHalf directly
+ unified the signature as "VP8LProcessBlueAndRedFunc"
no speed diff observed
Change-Id: Ic3c45dff11884a8330a9ad38c2c8e82491c6e044
With -bypass_filter switched on, the lossless-compressed
data is decoded ahead of time (before being transformed and
display). Hence, the last row was called twice.
http://code.google.com/p/webp/issues/detail?id=193
Change-Id: I9e13f495f6bd6f75fa84c4a21911f14c402d4b10
(and ~2-3% on ARM)
We don't need to store cost/score for each node, but only for
the current and previous one -> simplify code and save some memory.
Also made the 'Node' structure tighter.
Change-Id: Ie3ad7d3b678992b396242f56e2ac387fe43852e6
all the functions involved return double and later these locals are used
in double calculations. fixes a vs build warning
Change-Id: Idb547104ef00b48c71c124a774ef6f2ec5f30f14
Get back some of the compression gains by extending the search space for
GetBestGreenRedToBlue. Also removed the SkipRepeatedPixels call, as it was not
helping much in yielding better compression density.
Before:
1000 files, 63530337 pixels, 1 loops => 45.0s (45.0 ms/file/iterations)
Compression (output/input): 2.463/3.268 bpp, Encode rate (raw data): 1.347 MP/s
After:
1000 files, 63530337 pixels, 1 loops => 45.9s (45.9 ms/file/iterations)
Compression (output/input): 2.461/3.268 bpp, Encode rate (raw data): 1.321 MP/s
Change-Id: I044ba9d3f5bec088305e94a7c40c053ca237fd9d
Optimize and re-structured VP8LGetHistoImageSymbols method, by using the bin-hash
for merging the Histograms more efficiently, instead of the randomized
heuristic of existing method HistogramCombine.
This change speeds up the Lossless encoding by 40-50% (for method=4 and Q > 50)
with 0.8% penalty in compression density. For lower method, the speed up is 25-30%,
with 0.4% penalty in the compression density.
Change-Id: If61adadb1a041b95def6405aa1fe3b83c3cb25ce
Restructure PredictorInverseTransform & ColorSpaceInverseTransform to remove
one if condition inside the main/critial loop. Also separated TransformColor &
TransformColorInverse into separate functions and avoid one 'if condition'
inside this critical method.
This change speeds up lossless decoding for Lenna image about 5% and 1000 image
corpus by 3-4%.
Change-Id: I4bd390ffa4d3bcf70ca37ef2ff2e81bedbba197d
These are presets for lossless coding, similar to zlib.
The shortcut for lossless coding is now, e.g.:
cwebp -z 5 in.png -o out_lossless.webp
There are 10 possible values for -z parameter:
0 (fastest, lowest compression)
to 9 (slowest, best compression)
A reasonable tradeoff is -z 6, e.g.
-z 9 can be quite slow, so use with care.
This -z option is just a shortcut for some pre-defined
'-lossless -m xx -q yy' combinations.
Change-Id: I6ae716456456aea065469c916c2d5ca4d6c6cf04
(We didn't need the exact value of the max_error properly.
We can work with relative values instead of absolute)
Output is bitwise the same as before.
Change-Id: I67aeaaea5f81bfd9ca8e1158387a5083a2b6c649
Refactor code for HistogramCombine and optimize the code by calculating
the combined entropy and avoid un-necessary Histogram merges.
This speeds up lossless encoding by 1-2% and almost no impact on compression
density.
Change-Id: Iedfcf4c1f3e88077bc77fc7b8c780c4cd5d6362b
mostly by:
- storing a single rd-score instead of cost / distortion separately
- evaluating terminal cost only once
- getting some invariants out of the loops
- more consts behind fewer variables
Change-Id: I79451f3fd1143d6537200fb8b90d0ba252809f8c
incorporate non-last cost in per-level cost table
also: correct trellis-quant cost evaluation at nodes
(output a little bit different now). Method 6 is ~4% faster.
Change-Id: Ic48bd6d33f9193838216e7dc3a9f9c5508a1fbe8
Speedup lossless encoder by 20-25% by optimizing:
- GetBestColorTransformForTile: Use techniques like binary search and
local minima search to reduce the search space.
- VP8LFastSLog2Slow & VP8LFastLog2Slow: Adding the correction factor for
log(1 + x) and increase the threshold for calling the approximate
version of log_2 (compared to costly call to log()).
Change-Id: Ia2444c914521ac298492aafa458e617028fc2f9d
converts 2 s16 vectors to 2 u8 and store to uint8_t destination;
TransformAC3 can reuse this after a rework
Change-Id: Ia9370283ee3d9bfbc8c008fa883412100ff483d0
Separate the C version from the MIPS32 version and have run-time
initialization during RescalerInit()
Change-Id: I93cfa5691c073a099fe62eda1333ad2bb749915b
Increase the initial buffer size for VP8L Bit Writer from 4bpp to 8bpp.
The resize buffer is expensive (requires realloc and copy) and this additional
memory (0.5 * W * H) doesn't add much overhead on the lossless encoder.
Change-Id: Ic1fe55cd7bc3d1afadc799e4c2c8786ec848ee66
Optimize 'VP8LCalculateEstimateForCacheSize' for lower quality ranges (Q < 50).
The entropy is generally lower for higher cache_bits, so start searching from
higher cache_bits and settle for a local minima, instead of evaluating all
values.
This speeds up the lossless encoding at lower qualities by 10-15%.
Change-Id: I33c1e958515a2549f2e6f64b1aab3f128660dcec
* simplify the endian logic
* remove the need for memset()
* write 16 or 32 at a time (likely aligned)
Makes the code a bit faster on ARM (~1%)
Change-Id: I650bc5654e8d0b0454318b7a78206b301c5f6c2c
