Optimizes YUV to RGB conversion using ARMv5 multiply-accumulate
intructions for operations and data tables for saturation.
This first patch set includes the three versions i have developed.
Although iPod Classic need to use the latest version to reach 30fps,
old versions may serve other targets.
All versions are based on current SVN algorithm (round->scale->add)
using the same coefficients, so output results are identical.
Version history:
ARMv4:
- use all available registers to calculate four pixels within each
loop iteration.
- avoid LDR interlocks.
ARMv5TE:
- use ARMv5TE+ 1-cycle multiply-accumulate instructions.
ARMv5TE_WST:
- use data tables (256 bytes) for RBG565 saturation.
Benchmarks results using iPod Classic (ARM926EJ 216Mhz):
size test_fps (1) mpegplayer (2)
bytes YUV YUV1/4 average min/max
----- ----------- ------------------
SVN-20141107 528 27.8 110.0 11035 10864/13397
ARMv4 480 28.8 114.0 9767 9586/12126
ARMv5TE 468 29.7 117.5 8751 8584/11118
ARMv5TE_WST 544 33.6 133.0 6355 6316/6403
(1) boosted
(2) play full elephants_dream_320x240.mpg file (15693 frames) using
mpegplayer, patched RB measures YUV to RGB565 frame conversion
time (microseconds)
Compared against the WST version, the ARMV5TE version w/o cached
saturation tables is slower, but it is smaller and i have doubts
about the power consumption.
Change-Id: I2b6a81804636658d85a1bb104ccb2055e77ac120
Reviewed-on: http://gerrit.rockbox.org/1034
Reviewed-by: Cástor Muñoz <cmvidal@gmail.com>
Tested: Cástor Muñoz <cmvidal@gmail.com>
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