Changes to crc32 and st verify_benchmark routines

[vb000]

• The crc32 result verified against (here) seems to be wrong. An x86 machine and a RISC-V machine appear to converge on 171698305.
• If compiler optimization optimized this line, Coef = numerator / (sqrt(Aterm) * sqrt(Bterm));,
  into Coef = numerator / (sqrt(Aterm*Bterm));, the double FP result would be slightly different. To avoid failures due to these logically equivalent transformations, I added an epsilon check.

[bbbrumley]

I don't think that's the issue. I think the benchmark is returning 1 on success and 0 on failure, when it should be the opposite.

diff --git a/src/crc32/crc_32.c b/src/crc32/crc_32.c
index ad53ddd..a22f46f 100644
--- a/src/crc32/crc_32.c
+++ b/src/crc32/crc_32.c
@@ -202,9 +202,7 @@ int verify_benchmark(int r)
 {
   int expected = 1207487004;
 
-  if (r != expected)
-    return 0;
-  return 1;
+  return r != expected;
 }

[bbbrumley]

... or maybe I'm wrong and am misunderstanding the API.

But either way, I can verify both my x86_64 and armv7l targets did not like this test.

beebs/src/crc32$ ./crc32 
beebs/src/crc32$ echo $?
1

[bbbrumley]

Yea I was wrong -- the expected result is 0xfbda96cd. I checked it in a debugger, and also verified by dumping the binary inputs and checking with an external crc32 utility. So the fix is

diff --git a/src/crc32/crc_32.c b/src/crc32/crc_32.c
index ad53ddd..b65b31e 100644
--- a/src/crc32/crc_32.c
+++ b/src/crc32/crc_32.c
@@ -200,7 +200,7 @@ int benchmark()
 
 int verify_benchmark(int r)
 {
-  int expected = 1207487004;
+  int expected = -69560627;
 
   if (r != expected)
     return 0;