moar changes

mac implementation had _mm_div (x86 intrinsic)

Engine/source/math/isa/sse41/float4.cpp

@@ -0,0 +1,67 @@
+
+#include "float4_dispatch.h"
+#include <smmintrin.h> // SSE41 intrinsics
+
+namespace
+{
+   typedef __m128 f32x4;
+
+   // Load 4 floats from memory into a SIMD register
+   inline f32x4 v_load(const float* p) { return _mm_loadu_ps(p); }
+
+   // Store 4 floats from SIMD register back to memory
+   inline void v_store(float* dst, f32x4 v) { _mm_storeu_ps(dst, v); }
+
+   // Broadcast a single float across all 4 lanes
+   inline f32x4 v_set1(float s) { return _mm_set1_ps(s); }
+
+   // Element-wise multiply
+   inline f32x4 v_mul(f32x4 a, f32x4 b) { return _mm_mul_ps(a, b); }
+
+   // Element-wise divide
+   inline f32x4 v_div(f32x4 a, f32x4 b) { return _mm_div_ps(a, b); }
+
+   // Element-wise add
+   inline f32x4 v_add(f32x4 a, f32x4 b) { return _mm_add_ps(a, b); }
+
+   // Element-wise subtract
+   inline f32x4 v_sub(f32x4 a, f32x4 b) { return _mm_sub_ps(a, b); }
+
+   // Horizontal sum of all 4 elements (for dot product, length, etc.)
+   inline float v_hadd4(f32x4 a)
+   {
+      __m128 t1 = _mm_hadd_ps(a, a);  // sums pairs: [a0+a1, a2+a3, ...]
+      __m128 t2 = _mm_hadd_ps(t1, t1); // sums again: first element = a0+a1+a2+a3
+      return _mm_cvtss_f32(t2);       // extract first element
+   }
+
+   // specialized dot product for SSE4.1
+   float float4_dot_sse41(const float* a, const float* b)
+   {
+      f32x4 va = _mm_loadu_ps(a);
+      f32x4 vb = _mm_loadu_ps(b);
+      __m128 dp = _mm_dp_ps(va, vb, 0xF1); // multiply all 4, sum all 4, lowest lane
+      return _mm_cvtss_f32(dp);
+   }
+}
+
+#include "float4_impl.inl"
+
+namespace math_backend::float4::dispatch
+{
+   // Install SSE41 backend
+   void install_sse41()
+   {
+      gFloat4.add          = float4_add_impl;
+      gFloat4.sub          = float4_sub_impl;
+      gFloat4.mul          = float4_mul_impl;
+      gFloat4.mul_scalar   = float4_mul_scalar_impl;
+      gFloat4.div          = float4_div_impl;
+      gFloat4.div_scalar   = float4_div_scalar_impl;
+      gFloat4.dot          = float4_dot_sse41;
+      gFloat4.length       = float4_length_impl;
+      gFloat4.lengthSquared = float4_length_squared_impl;
+      gFloat4.normalize    = float4_normalize_impl;
+      gFloat4.lerp         = float4_lerp_impl;
+   }
+}