bloom.c: add the murmur3 hash implementation

In preparation for computing changed paths Bloom filters,
implement the Murmur3 hash algorithm as described in [1].
It hashes the given data using the given seed and produces
a uniformly distributed hash value.

[1] https://en.wikipedia.org/wiki/MurmurHash#Algorithm

Helped-by: Derrick Stolee <dstolee@microsoft.com>
Helped-by: Szeder Gábor <szeder.dev@gmail.com>
Reviewed-by: Jakub Narębski <jnareb@gmail.com>
Signed-off-by: Garima Singh <garima.singh@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 30 insertions, 0 deletions

diff --git a/t/t0095-bloom.sh b/t/t0095-bloom.sh
new file mode 100755
index 0000000000..2dad8c4a94
--- /dev/null
+++ b/t/t0095-bloom.sh
@@ -0,0 +1,30 @@
+#!/bin/sh
+
+test_description='Testing the various Bloom filter computations in bloom.c'
+. ./test-lib.sh
+
+test_expect_success 'compute unseeded murmur3 hash for empty string' '
+	cat >expect <<-\EOF &&
+	Murmur3 Hash with seed=0:0x00000000
+	EOF
+	test-tool bloom get_murmur3 "" >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'compute unseeded murmur3 hash for test string 1' '
+	cat >expect <<-\EOF &&
+	Murmur3 Hash with seed=0:0x627b0c2c
+	EOF
+	test-tool bloom get_murmur3 "Hello world!" >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'compute unseeded murmur3 hash for test string 2' '
+	cat >expect <<-\EOF &&
+	Murmur3 Hash with seed=0:0x2e4ff723
+	EOF
+	test-tool bloom get_murmur3 "The quick brown fox jumps over the lazy dog" >actual &&
+	test_cmp expect actual
+'
+
+test_done
\ No newline at end of file