fix sbgemm bfloat16 conversion errors introduced in PR 4488

Author: martin-frbg

test/compare_sgemm_sbgemm.c

@@ -81,16 +81,6 @@ float16to32 (bfloat16_bits f16)
   return f32.v;
 }
 
-float
-float32to16 (float32_bits f32)
-{
-  bfloat16_bits f16;
-  f16.bits.s = f32.bits.s;
-  f16.bits.e = f32.bits.e;
-  f16.bits.m = (uint32_t) f32.bits.m >> 16;
-  return f32.v;
-}
-
 int
 main (int argc, char *argv[])
 {
@@ -110,6 +100,8 @@ main (int argc, char *argv[])
       float C[m * n];
       bfloat16_bits AA[m * k], BB[k * n];
       float DD[m * n], CC[m * n];
+      bfloat16 atmp,btmp;
+      blasint one=1;
 
       for (j = 0; j < m; j++)
 	{
@@ -118,8 +110,10 @@ main (int argc, char *argv[])
 	      A[j * k + i] = ((FLOAT) rand () / (FLOAT) RAND_MAX) + 0.5;
 	      B[j * k + i] = ((FLOAT) rand () / (FLOAT) RAND_MAX) + 0.5;
 	      C[j * k + i] = 0;
-	      AA[j * k + i].v = float32to16( A[j * k + i] );
-	      BB[j * k + i].v = float32to16( B[j * k + i] );
+	      sbstobf16_(&one, &A[j*k+i], &one, &atmp, &one);
+	      sbstobf16_(&one, &B[j*k+i], &one, &btmp, &one);
+	      AA[j * k + i].v = atmp;
+	      BB[j * k + i].v = btmp;
 	      CC[j * k + i] = 0;
 	      DD[j * k + i] = 0;
 	    }