diff --git a/mllm/backends/cpu/ops/CausalMaskOp.cpp b/mllm/backends/cpu/ops/CausalMaskOp.cpp
index 074ca019..56fc0b7f 100644
--- a/mllm/backends/cpu/ops/CausalMaskOp.cpp
+++ b/mllm/backends/cpu/ops/CausalMaskOp.cpp
@@ -50,13 +50,14 @@ void CPUCausalMaskOp::forward(const std::vector<Tensor>& inputs, std::vector<Ten
 
           if (!options_.sliding_window) {
             // Standard causal mask
-#if defined(MLLM_HOST_ARCH_X86_64) || defined(MLLM_HOST_ARCH_X86) && defined(__AVX2__)
+#if (defined(MLLM_HOST_ARCH_X86_64) || defined(MLLM_HOST_ARCH_X86)) && defined(__AVX2__)
             const __m256 mask_val = _mm256_set1_ps(-1e10f);
             for (size_t r = 0; r < S; ++r) {
+              const size_t row_offset = r * D;
               const size_t copy_count = D - S + r + 1;
               const size_t fill_count = std::max(D - copy_count, (size_t)0);
 
-              memcpy(o_ptr + r * D, i_ptr + r * D, copy_count * sizeof(float));
+              memcpy(o_ptr + row_offset, i_ptr + row_offset, copy_count * sizeof(float));
 
               float* fill_start = o_ptr + row_offset + copy_count;
               size_t avx_iters = fill_count / 8;
@@ -81,6 +82,17 @@ void CPUCausalMaskOp::forward(const std::vector<Tensor>& inputs, std::vector<Ten
               for (size_t i = 0; i < neon_iters; ++i) { vst1q_f32(fill_start + i * 4, mask_val); }
               for (size_t i = 0; i < remainder; ++i) { fill_start[neon_iters * 4 + i] = -1e10f; }
             }
+#else
+            for (size_t r = 0; r < S; ++r) {
+              const size_t row_offset = r * D;
+              const size_t copy_count = D - S + r + 1;
+              const size_t fill_count = std::max(D - copy_count, (size_t)0);
+
+              memcpy(o_ptr + row_offset, i_ptr + row_offset, copy_count * sizeof(float));
+
+              float* fill_start = o_ptr + row_offset + copy_count;
+              for (size_t i = 0; i < fill_count; ++i) { fill_start[i] = -1e10f; }
+            }
 #endif
           } else {
             // Sliding window causal mask
@@ -98,7 +110,7 @@ void CPUCausalMaskOp::forward(const std::vector<Tensor>& inputs, std::vector<Ten
               const size_t suffix_fill_start_idx = s + 1;
               const size_t suffix_fill_count = S - suffix_fill_start_idx;
 
-#if defined(MLLM_HOST_ARCH_X86_64) || defined(MLLM_HOST_ARCH_X86) && defined(__AVX2__)
+#if (defined(MLLM_HOST_ARCH_X86_64) || defined(MLLM_HOST_ARCH_X86)) && defined(__AVX2__)
               const __m256 mask_val = _mm256_set1_ps(-1e10f);
               // Fill prefix
               float* prefix_fill_start = o_ptr + row_offset;
@@ -118,6 +130,11 @@ void CPUCausalMaskOp::forward(const std::vector<Tensor>& inputs, std::vector<Ten
               float* suffix_fill_start = o_ptr + row_offset + suffix_fill_start_idx;
               for (size_t i = 0; i < suffix_fill_count / 4; ++i) vst1q_f32(suffix_fill_start + i * 4, mask_val);
               for (size_t i = (suffix_fill_count / 4) * 4; i < suffix_fill_count; ++i) suffix_fill_start[i] = -1e10f;
+#else
+              float* prefix_fill_start = o_ptr + row_offset;
+              for (size_t i = 0; i < prefix_fill_count; ++i) { prefix_fill_start[i] = -1e10f; }
+              float* suffix_fill_start = o_ptr + row_offset + suffix_fill_start_idx;
+              for (size_t i = 0; i < suffix_fill_count; ++i) { suffix_fill_start[i] = -1e10f; }
 #endif
             }
           }
@@ -143,7 +160,7 @@ void CPUCausalMaskOp::forward(const std::vector<Tensor>& inputs, std::vector<Ten
 
           if (!options_.sliding_window) {
             // Standard causal mask
-#if defined(MLLM_HOST_ARCH_X86_64) || defined(MLLM_HOST_ARCH_X86) && defined(__AVX2__) && defined(__F16C__)
+#if (defined(MLLM_HOST_ARCH_X86_64) || defined(MLLM_HOST_ARCH_X86)) && defined(__AVX2__) && defined(__F16C__)
             const __m256 mask_ps = _mm256_set1_ps(-65500.f);
             const __m128i mask_val = _mm256_cvtps_ph(mask_ps, _MM_FROUND_TO_NEAREST_INT);
             for (size_t s = 0; s < S; ++s) {
@@ -178,6 +195,17 @@ void CPUCausalMaskOp::forward(const std::vector<Tensor>& inputs, std::vector<Ten
               for (size_t i = 0; i < neon_iters; ++i) { vst1q_f16(fill_start + i * 8, mask_val); }
               for (size_t i = 0; i < remainder; ++i) { fill_start[neon_iters * 8 + i] = -65500.f; }
             }
+#else
+            for (size_t s = 0; s < S; ++s) {
+              const size_t row_offset = s * S;
+              const size_t copy_count = s + 1;
+              const size_t fill_count = S - copy_count;
+
+              if (copy_count > 0) { memcpy(o_ptr + row_offset, i_ptr + row_offset, copy_count * sizeof(mllm_fp16_t)); }
+
+              mllm_fp16_t* fill_start = o_ptr + row_offset + copy_count;
+              for (size_t i = 0; i < fill_count; ++i) { fill_start[i] = -65500.f; }
+            }
 #endif
           } else {
             // Sliding window causal mask
@@ -196,7 +224,7 @@ void CPUCausalMaskOp::forward(const std::vector<Tensor>& inputs, std::vector<Ten
               const size_t suffix_fill_start_idx = s + 1;
               const size_t suffix_fill_count = S - suffix_fill_start_idx;
 
-#if defined(MLLM_HOST_ARCH_X86_64) || defined(MLLM_HOST_ARCH_X86) && defined(__AVX2__) && defined(__F16C__)
+#if (defined(MLLM_HOST_ARCH_X86_64) || defined(MLLM_HOST_ARCH_X86)) && defined(__AVX2__) && defined(__F16C__)
               const __m256 mask_ps = _mm256_set1_ps(-65500.f);
               const __m128i mask_val = _mm256_cvtps_ph(mask_ps, _MM_FROUND_TO_NEAREST_INT);
 
@@ -222,6 +250,11 @@ void CPUCausalMaskOp::forward(const std::vector<Tensor>& inputs, std::vector<Ten
               mllm_fp16_t* suffix_fill_start = o_ptr + row_offset + suffix_fill_start_idx;
               for (size_t i = 0; i < suffix_fill_count / 8; ++i) vst1q_f16(suffix_fill_start + i * 8, mask_val);
               for (size_t i = (suffix_fill_count / 8) * 8; i < suffix_fill_count; ++i) suffix_fill_start[i] = -65500.f;
+#else
+              mllm_fp16_t* prefix_fill_start = o_ptr + row_offset;
+              for (size_t i = 0; i < prefix_fill_count; ++i) { prefix_fill_start[i] = -65500.f; }
+              mllm_fp16_t* suffix_fill_start = o_ptr + row_offset + suffix_fill_start_idx;
+              for (size_t i = 0; i < suffix_fill_count; ++i) { suffix_fill_start[i] = -65500.f; }
 #endif
             }
           }
diff --git a/mllm/engine/HpcThreadPool.cpp b/mllm/engine/HpcThreadPool.cpp
index ab24d663..9d552d23 100644
--- a/mllm/engine/HpcThreadPool.cpp
+++ b/mllm/engine/HpcThreadPool.cpp
@@ -96,21 +96,21 @@ void HpcThreadPool::splitTask(HpcThreadPoolTask&& task, int task_slot_idx) {
   //  0, 1, 2, 3, 0, 1, 2, 3, 0, 1, 2, 3
   if (tiles_num > thread_cnt_) {
     tasks_[task_slot_idx].first = {
-        .start = 0,
-        .end = thread_cnt_,
-        .step = 1,
         .func =
             [tiles_num, &task, &true_idx, this](int thread_idx) {
               for (int v = thread_idx; v < tiles_num; v += thread_cnt_) { task.func(true_idx[v]); }
             },
+        .start = 0,
+        .end = thread_cnt_,
+        .step = 1,
     };
     tiles_num = thread_cnt_;
   } else {
     tasks_[task_slot_idx].first = {
+        .func = [tiles_num, &task, &true_idx, this](int thread_idx) { task.func(true_idx[thread_idx]); },
         .start = 0,
         .end = tiles_num,
         .step = 1,
-        .func = [tiles_num, &task, &true_idx, this](int thread_idx) { task.func(true_idx[thread_idx]); },
     };
   }
   {
diff --git a/mllm/models/minicpm_o2_6/streaming_generation.hpp b/mllm/models/minicpm_o2_6/streaming_generation.hpp
index 4de6ecc5..eb382e72 100644
--- a/mllm/models/minicpm_o2_6/streaming_generation.hpp
+++ b/mllm/models/minicpm_o2_6/streaming_generation.hpp
@@ -96,7 +96,7 @@ class StreamingGenerator {
         config_(config) {
     // Configure chunk generation
     models::ChunkGenerationConfig chunk_config{
-        .chunk_size = 5, .max_new_tokens = 10, .do_sample = false, .save_first_chunk_hidden_states = true};
+        .max_new_tokens = 10, .chunk_size = 5, .do_sample = false, .save_first_chunk_hidden_states = true};
 
     // Add EOS tokens for MiniCPMO
     auto eos_ids = tokenizer_.convert2Ids({L"<|im_end|>"});
diff --git a/tests/cpu/CausalMaskOpTest.hpp b/tests/cpu/CausalMaskOpTest.hpp
new file mode 100644
index 00000000..9969d36c
--- /dev/null
+++ b/tests/cpu/CausalMaskOpTest.hpp
@@ -0,0 +1,66 @@
+#pragma once
+
+#include <algorithm>
+
+#include "KernelTestHelper.hpp"
+#include "mllm/mllm.hpp"
+#include "mllm/nn/layers/CausalMask.hpp"
+
+class CausalMaskOpTest : public KernelTest {
+ public:
+  void SetUp() override {
+    KernelTest::SetUp();
+    mask_.to(mllm::kCPU);
+  }
+
+  mllm::test::AllCloseResult runScenario(int B, int H, int S, int D) {
+    using namespace mllm;  // NOLINT
+    const int64_t total = static_cast<int64_t>(B) * H * S * D;
+    auto input = Tensor::arange(0, static_cast<float>(total), 1, kFloat32, kCPU).view({B, H, S, D});
+    auto output = mask_(input);
+    auto expected = buildExpectedTensor(input);
+    auto result = test::allClose(expected, output);
+    if (!result) {
+      mllm::print(result);
+      mllm::print(expected);
+      mllm::print(output);
+    }
+    return result;
+  }
+
+ private:
+  static mllm::Tensor buildExpectedTensor(const mllm::Tensor& input) {
+    using namespace mllm;  // NOLINT
+    auto shape = input.shape();
+    const int B = shape[0];
+    const int H = shape[1];
+    const int S = shape[2];
+    const int D = shape[3];
+    auto expected = Tensor::zeros(shape, kFloat32, kCPU);
+
+    const float* in_ptr = input.ptr<float>();
+    float* exp_ptr = expected.ptr<float>();
+    const int context_offset = std::max(0, D - S);
+    const float mask_value = -1e10f;
+
+    for (int b = 0; b < B; ++b) {
+      for (int h = 0; h < H; ++h) {
+        for (int s = 0; s < S; ++s) {
+          const int allowed = std::min(D, context_offset + s + 1);
+          for (int d = 0; d < D; ++d) {
+            const int64_t idx = (((static_cast<int64_t>(b) * H) + h) * S + s) * D + d;
+            if (d < allowed) {
+              exp_ptr[idx] = in_ptr[idx];
+            } else {
+              exp_ptr[idx] = mask_value;
+            }
+          }
+        }
+      }
+    }
+    return expected;
+  }
+
+  mllm::nn::CausalMask mask_;
+};
+
diff --git a/tests/cpu/KernelTest.cpp b/tests/cpu/KernelTest.cpp
index fb595c79..9f8d613e 100644
--- a/tests/cpu/KernelTest.cpp
+++ b/tests/cpu/KernelTest.cpp
@@ -533,6 +533,25 @@ TEST_F(ElementwiseKernelTest, DivScalarInt32) {
             true);
 }
 
+//===----------------------------------------------------------------------===//
+// CausalMaskOp
+//===----------------------------------------------------------------------===//
+#include "CausalMaskOpTest.hpp"
+TEST_F(CausalMaskOpTest, PrefillScenario) {
+  auto result = runScenario(1, 1, 4, 4);
+  EXPECT_TRUE(result.is_close);
+}
+
+TEST_F(CausalMaskOpTest, DecodeScenario) {
+  auto result = runScenario(1, 1, 1, 6);
+  EXPECT_TRUE(result.is_close);
+}
+
+TEST_F(CausalMaskOpTest, AppendScenario) {
+  auto result = runScenario(2, 3, 3, 7);
+  EXPECT_TRUE(result.is_close);
+}
+
 //===----------------------------------------------------------------------===//
 // GELU
 //===----------------------------------------------------------------------===//