libyuv/docs/environment_variables.md
Frank Barchard 9a07219dc8 Documentation update for GYP and envionment variables
Bug: libyuv:816, libyuv:804
Change-Id: I73a6960b2cc6f3ca31c43c44ccd8b01f5e9e7013
Test" Untested
Reviewed-on: https://chromium-review.googlesource.com/1205053
Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Frank Barchard <fbarchard@chromium.org>
2018-09-04 19:45:41 +00:00

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1.4 KiB
Markdown

# Introduction
For test purposes, environment variables can be set to control libyuv behavior. These should only be used for testing, to narrow down bugs or to test performance.
# CPU
By default the cpu is detected and the most advanced form of SIMD is used. But you can disable instruction sets selectively, or completely, falling back on C code. Set the variable to 1 to disable the specified instruction set.
## All CPUs
LIBYUV_DISABLE_ASM
## Intel CPUs
LIBYUV_DISABLE_X86
LIBYUV_DISABLE_SSE2
LIBYUV_DISABLE_SSSE3
LIBYUV_DISABLE_SSE41
LIBYUV_DISABLE_SSE42
LIBYUV_DISABLE_AVX
LIBYUV_DISABLE_AVX2
LIBYUV_DISABLE_ERMS
LIBYUV_DISABLE_FMA3
LIBYUV_DISABLE_F16C
LIBYUV_DISABLE_AVX512BW
LIBYUV_DISABLE_AVX512VL
LIBYUV_DISABLE_AVX512VBMI
LIBYUV_DISABLE_AVX512VBMI2
LIBYUV_DISABLE_AVX512VBITALG
LIBYUV_DISABLE_AVX512VPOPCNTDQ
LIBYUV_DISABLE_GFNI
## ARM CPUs
LIBYUV_DISABLE_NEON
## MIPS CPUs
LIBYUV_DISABLE_MSA
LIBYUV_DISABLE_MMI
# Test Width/Height/Repeat
The unittests default to a small image (128x72) to run fast. This can be set by environment variable to test a specific resolutions.
You can also repeat the test a specified number of iterations, allowing benchmarking and profiling.
set LIBYUV_WIDTH=1280
set LIBYUV_HEIGHT=720
set LIBYUV_REPEAT=999
set LIBYUV_FLAGS=-1
set LIBYUV_CPU_INFO=-1