Chore: Clean-up substract_bf16x32_genoa

Relates to #160

include/simsimd/spatial.h

@@ -1128,30 +1128,33 @@ SIMSIMD_INTERNAL __m512i simsimd_substract_bf16x32_genoa(__m512i a_i16, __m512i
     b.ivec = b_i16;
 
     // Let's perform the subtraction with single-precision, while the dot-product with half-precision.
-    // For that we need to perform a couple of casts - each is a bitshift. To convert `bf16` to `f32`,
-    // expand it to 32-bit integers, then shift the bits by 16 to the left. Then subtract as floats,
-    // and shift back. During expansion, we will double the space, and should use separate registers
-    // for top and bottom halves.
-    a_f32_bot.fvec = _mm512_castsi512_ps(_mm512_slli_epi32(_mm512_cvtepu16_epi32(_mm512_castsi512_si256(a_i16)), 16));
-    b_f32_bot.fvec = _mm512_castsi512_ps(_mm512_slli_epi32(_mm512_cvtepu16_epi32(_mm512_castsi512_si256(b_i16)), 16));
-
-    // Some compilers don't have `_mm512_extracti32x8_epi32`, so we need to use `_mm512_extracti64x4_epi64`
-    a_f32_top.fvec =
-        _mm512_castsi512_ps(_mm512_slli_epi32(_mm512_cvtepu16_epi32(_mm512_extracti64x4_epi64(a_i16, 1)), 16));
-    b_f32_top.fvec =
-        _mm512_castsi512_ps(_mm512_slli_epi32(_mm512_cvtepu16_epi32(_mm512_extracti64x4_epi64(b_i16, 1)), 16));
-
-    // Subtract in single precision
-    d_f32_top.fvec = _mm512_sub_ps(a_f32_top.fvec, b_f32_top.fvec);
-    d_f32_bot.fvec = _mm512_sub_ps(a_f32_bot.fvec, b_f32_bot.fvec);
-
-    // Now, let's populate one ZMM register with the top 16 bits of every 32-bit float,
-    // in the "top", followed by the top parts of the "bottom" floats. Instead of using multple
-    // shifts and blends, we can achieve that with cheap `_mm512_mask_shuffle_epi8`, or a more
-    // expensive `_mm512_permutex2var_epi16`.
-    d.ivec = _mm512_castsi256_si512(_mm512_cvtepi32_epi16(_mm512_srli_epi32(_mm512_castps_si512(d_f32_bot.fvec), 16)));
-    d.ivec = _mm512_inserti64x4(d.ivec,
-                                _mm512_cvtepi32_epi16(_mm512_srli_epi32(_mm512_castps_si512(d_f32_top.fvec), 16)), 1);
+    //
+    // There are several approaches to achieve this this. The first one is:
+    //
+    //      Perform a couple of casts - each is a bitshift. To convert `bf16` to `f32`,
+    //      expand it to 32-bit integers, then shift the bits by 16 to the left.
+    //      Then subtract as floats, and shift back. During expansion, we will double the space,
+    //      and should use separate registers for top and bottom halves.
+    //      Some compilers don't have `_mm512_extracti32x8_epi32`, so we use `_mm512_extracti64x4_epi64`:
+    //
+    //          a_f32_bot.fvec = _mm512_castsi512_ps(_mm512_slli_epi32(
+    //              _mm512_cvtepu16_epi32(_mm512_castsi512_si256(a_i16)), 16));
+    //          b_f32_bot.fvec = _mm512_castsi512_ps(_mm512_slli_epi32(
+    //              _mm512_cvtepu16_epi32(_mm512_castsi512_si256(b_i16)), 16));
+    //          a_f32_top.fvec =_mm512_castsi512_ps(
+    //              _mm512_slli_epi32(_mm512_cvtepu16_epi32(_mm512_extracti64x4_epi64(a_i16, 1)), 16));
+    //          b_f32_top.fvec =_mm512_castsi512_ps(
+    //              _mm512_slli_epi32(_mm512_cvtepu16_epi32(_mm512_extracti64x4_epi64(b_i16, 1)), 16));
+    //          d_f32_top.fvec = _mm512_sub_ps(a_f32_top.fvec, b_f32_top.fvec);
+    //          d_f32_bot.fvec = _mm512_sub_ps(a_f32_bot.fvec, b_f32_bot.fvec);
+    //          d.ivec = _mm512_castsi256_si512(_mm512_cvtepi32_epi16(
+    //              _mm512_srli_epi32(_mm512_castps_si512(d_f32_bot.fvec), 16)));
+    //          d.ivec = _mm512_inserti64x4(d.ivec, _mm512_cvtepi32_epi16(
+    //              _mm512_srli_epi32(_mm512_castps_si512(d_f32_top.fvec), 16)), 1);
+    //
+    // Instead of using multple shifts and an insertion, we can achieve similar result with fewer expensive
+    // calls to `_mm512_permutex2var_epi16`, or a cheap `_mm512_mask_shuffle_epi8` and blend:
+
     return d.ivec;
 }