cpu.x86: Add ghetto RDRAND support. Proper support wouldn't use alien-assembly and would take a count parameter.

basis/cpu/x86/assembler/assembler.factor

@@ -451,6 +451,8 @@ PRIVATE>
 : RDMSR ( -- ) 0x0f , 0x32 , ; ! Only available in privileged level 0
 : RDPMC ( -- ) 0x0f , 0x33 , ;
 
+: RDRAND ( dst -- ) { 0b110 t { 0x0f 0xc7 } } 1-operand ;
+
 ! x87 Floating Point Unit
 
 : FSTPS ( operand -- ) { 0b011 f 0xd9 } 1-operand ;

basis/cpu/x86/features/features.factor

@@ -141,6 +141,26 @@ HOOK: (cpuid) cpu ( rax rcx regs -- )
 : tm1? ( -- ? ) 1 cpuid fourth 29 bit? ;
 : tm2? ( -- ? ) 1 cpuid third 8 bit? ;
 
+: rdrand8 ( -- x )
+    uchar { } cdecl [
+        AL RDRAND
+    ] alien-assembly ;
+
+: rdrand16 ( -- x )
+    ushort { } cdecl [
+        AX RDRAND
+    ] alien-assembly ;
+
+: rdrand32 ( -- x )
+    uint { } cdecl [
+        EAX RDRAND
+    ] alien-assembly ;
+
+: rdrand64 ( -- x )
+    ulonglong { } cdecl [
+        RAX RDRAND
+    ] alien-assembly ;
+
 MEMO: enable-popcnt? ( -- ? )
     popcnt? "disable-popcnt" get not and ;