From 3da31de4c072f7256bf0d3477ca75e78078183e4 Mon Sep 17 00:00:00 2001
From: biondizzle <biondizzle@gmail.com>
Date: Sat, 30 May 2026 09:04:05 +0000
Subject: [PATCH] P5: fix BF16 host helpers for standalone test

---
 tests/unit/test_p5_multitile.cu | 25 +++++++++++++++++--------
 1 file changed, 17 insertions(+), 8 deletions(-)

diff --git a/tests/unit/test_p5_multitile.cu b/tests/unit/test_p5_multitile.cu
index 3f567775..c10d4a2d 100644
--- a/tests/unit/test_p5_multitile.cu
+++ b/tests/unit/test_p5_multitile.cu
@@ -12,6 +12,15 @@
 
 using namespace dsv4::kernels::attention;
 
+// Host-side BF16 helpers
+static float hbf16_to_f32(uint16_t h) {
+    uint32_t u = ((uint32_t)h) << 16;
+    float f; memcpy(&f, &u, 4); return f;
+}
+static uint16_t hf32_to_bf16(float f) {
+    uint32_t u; memcpy(&u, &f, 4); return (uint16_t)(u >> 16);
+}
+
 // CPU reference attention for single head
 void reference_attention(
     const bf16_t* q, const bf16_t* k, const bf16_t* v,
@@ -23,7 +32,7 @@ void reference_attention(
     // Compute max
     for (int j = 0; j < s_k; j++) {
         float dot = 0.0f;
-        for (int d = 0; d < hd; d++) dot += bf16_to_f32(q[d]) * bf16_to_f32(k[j * hd + d]);
+        for (int d = 0; d < hd; d++) dot += hbf16_to_f32(q[d]) * hbf16_to_f32(k[j * hd + d]);
         dot *= scale;
         if (dot > row_max) row_max = dot;
     }
@@ -31,11 +40,11 @@ void reference_attention(
     float row_sum = 0.0f;
     for (int j = 0; j < s_k; j++) {
         float dot = 0.0f;
-        for (int d = 0; d < hd; d++) dot += bf16_to_f32(q[d]) * bf16_to_f32(k[j * hd + d]);
+        for (int d = 0; d < hd; d++) dot += hbf16_to_f32(q[d]) * hbf16_to_f32(k[j * hd + d]);
         dot *= scale;
         float p = expf(dot - row_max);
         row_sum += p;
-        for (int d = 0; d < hd; d++) o_ref[d] += p * bf16_to_f32(v[d * s_k + j]);
+        for (int d = 0; d < hd; d++) o_ref[d] += p * hbf16_to_f32(v[d * s_k + j]);
     }
     for (int d = 0; d < hd; d++) o_ref[d] /= row_sum;
     *lse_ref = logf(row_sum) + row_max;
@@ -51,9 +60,9 @@ int main() {
     float h_o_ref[HD], h_lse_ref;
 
     srand(42);
-    for (int d = 0; d < HD; d++) h_q[d] = f32_to_bf16((float)(rand() % 100) / 100.0f);
-    for (int j = 0; j < SK * HD; j++) h_k[j] = f32_to_bf16((float)(rand() % 100) / 100.0f);
-    for (int j = 0; j < HD * SK; j++) h_v[j] = f32_to_bf16((float)(rand() % 100) / 100.0f);
+    for (int d = 0; d < HD; d++) h_q[d] = hf32_to_bf16((float)(rand() % 100) / 100.0f);
+    for (int j = 0; j < SK * HD; j++) h_k[j] = hf32_to_bf16((float)(rand() % 100) / 100.0f);
+    for (int j = 0; j < HD * SK; j++) h_v[j] = hf32_to_bf16((float)(rand() % 100) / 100.0f);
 
     // CPU reference
     reference_attention(h_q, h_k, h_v, h_o_ref, &h_lse_ref, HD, SK, SCALE);
@@ -124,7 +133,7 @@ int main() {
     float cos = 0, norm_a = 0, norm_b = 0;
     for (int d = 0; d < HD; d++) {
         float a = h_o_ref[d];
-        float b = bf16_to_f32(h_o[d]);
+        float b = hbf16_to_f32(h_o[d]);
         cos += a * b;
         norm_a += a * a;
         norm_b += b * b;
@@ -135,7 +144,7 @@ int main() {
     printf("  LSE: kernel=%.4f ref=%.4f\n", h_lse, h_lse_ref);
     printf("  Cosine similarity: %.6f\n", cos);
     printf("  Kernel O[0:5]:");
-    for (int d = 0; d < 5; d++) printf(" %.4f", bf16_to_f32(h_o[d]));
+    for (int d = 0; d < 5; d++) printf(" %.4f", hbf16_to_f32(h_o[d]));
     printf("\n  Ref    O[0:5]:");
     for (int d = 0; d < 5; d++) printf(" %.4f", h_o_ref[d]);
     printf("\n");