Update platform for emscripten builds

Source/Base/dn_base.h

@@ -255,12 +255,16 @@ struct DN_CallSite
   #define DN_Atomic_SubU64(target, value)                          DN_Atomic_AddU64(target, (DN_U64) - value)
 
   #define DN_CountLeadingZerosU64(value)                           __lzcnt64(value)
+  #define DN_CountLeadingZerosU32(value)                           __lzcnt(value)
   #define DN_CPU_TSC()                                             __rdtsc()
   #define DN_CompilerReadBarrierAndCPUReadFence                    _ReadBarrier();  _mm_lfence()
   #define DN_CompilerWriteBarrierAndCPUWriteFence                  _WriteBarrier(); _mm_sfence()
 #elif defined(DN_COMPILER_GCC) || defined(DN_COMPILER_CLANG)
   #if defined(__ANDROID__)
   #elif defined(DN_PLATFORM_EMSCRIPTEN)
+    #if !defined(__wasm_simd128__)
+      #error DN_Base requires -msse2 to be passed to Emscripten
+    #endif
     #include <emmintrin.h>
   #else
     #include <x86intrin.h>
@@ -274,6 +278,8 @@ struct DN_CallSite
   #define DN_Atomic_SubU64(target, value)                          __atomic_fetch_sub(target, value, __ATOMIC_ACQ_REL)
 
   #define DN_CountLeadingZerosU64(value)                           __builtin_clzll(value)
+  #define DN_CountLeadingZerosU32(value)                           __builtin_clzl(value)
+
   #if defined(DN_COMPILER_GCC)
     #define DN_CPU_TSC() __rdtsc()
   #else
@@ -291,6 +297,12 @@ struct DN_CallSite
   #error "Compiler not supported"
 #endif
 
+#if defined(__aarch64__) || defined(_M_X64) || defined(__x86_64__) || defined(__x86_64)
+  #define DN_CountLeadingZerosUSize(value) DN_CountLeadingZerosU64(value)
+#else
+  #define DN_CountLeadingZerosUSize(value) DN_CountLeadingZerosU32(value)
+#endif
+
 #if !defined(DN_PLATFORM_ARM64)
 struct DN_CPURegisters
 {