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authorMatt A. Tobin <mattatobin@localhost.localdomain>2018-02-02 04:16:08 -0500
committerMatt A. Tobin <mattatobin@localhost.localdomain>2018-02-02 04:16:08 -0500
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+# 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.
+
+ LIBYUV_DISABLE_ASM
+ LIBYUV_DISABLE_X86
+ LIBYUV_DISABLE_SSE2
+ LIBYUV_DISABLE_SSSE3
+ LIBYUV_DISABLE_SSE41
+ LIBYUV_DISABLE_SSE42
+ LIBYUV_DISABLE_AVX
+ LIBYUV_DISABLE_AVX2
+ LIBYUV_DISABLE_AVX3
+ LIBYUV_DISABLE_ERMS
+ LIBYUV_DISABLE_FMA3
+ LIBYUV_DISABLE_DSPR2
+ LIBYUV_DISABLE_NEON
+
+# 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