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+crc32-s390x
+===========
+
+A library of functions for accelerating CRC32 calculations using the
+Vector Galois Field Multiply instruction family instructions introduced in
+the z13. The Vector Extension Facility for z/Architecture provides two
+instructions to perform a binary Galois field multiplication. Both
+instructions (VGFM and VGFMA) can operate on different element sizes.
+For the 32-bit CRC computation, doublewords are used throughout the
+implementation.
+
+Quick start
+-----------
+
+Type make to generate a static library libcrc32\_s390x.a.
+
+The library provides functions to compute CRC-32 (IEEE 802.3) and
+CRC-32C (Castagnoli), with optional bit reflection (with the `*_le`
+versions of the functions).
+
+Function prototypes are declared in crc32-s390x.h. A sample program
+crc32-cli.c shows how the library is used.
+
+Testing
+-------
+
+The correctness of the hardware-accelerated implementation is verified
+with the pure-software Rocksoft Model CRC algorithm. There are four
+variants of the test, each of which exercise one type of CRC on random
+data with random alignment and buffer sizes, in an infinite loop:
+
+    ./crc32_be_test
+    ./crc32_le_test
+    ./crc32c_be_test
+    ./crc32c_le_test
+
+If the hardware-accelerated algorithm ever returns a different result
+than the Rocksoft Model, the test will print messages to indicate the
+errors.
+
+Performance
+-----------
+
+The performance of the hardware-accelerated implemention is compared
+with the slicing-by-8 algorithm. Testing 500000 iterations of a CRC
+of 32kB of data showed a 70-times speed-up:
+
+    $ time ./crc32_sw_bench 32768 500000
+    CRC: a98177aa
+    
+    real    0m21.862s
+    user    0m21.859s
+    sys     0m0.002s
+    
+    $ time ./crc32_vx_bench 32768 500000
+    CRC: a98177aa
+    
+    real    0m0.323s
+    user    0m0.323s
+    sys     0m0.000s
+