/// Checking `rdrand'.
FUNC(dispatch_x86ish_rdrand)
- // Enter with one argument: a pointer X_OUT to a 32-bit word. Try to
- // generate a random word using `rdrand'. If successful, set *X_OUT
- // to the generated word, and return zero; otherwise, return -1.
+ // Enter with two arguments: a code OP requesting `rdrand' (0), and a
+ // pointer X_OUT to a 32-bit word. Try to generate a random word
+ // using the requested instruction. If successful, set *X_OUT to the
+ // generated word, and return zero; otherwise, return -1.
#if CPUFAM_X86
+# define OP eax
# define X_OUT edx
# define COUNT ecx
- mov X_OUT, [SP + 4]
+ mov OP, [SP + 4]
+ mov X_OUT, [SP + 8]
#endif
#if CPUFAM_AMD64 && ABI_SYSV
-# define X_OUT rdi
+# define OP edi
+# define X_OUT rsi
# define COUNT ecx
#endif
#if CPUFAM_AMD64 && ABI_WIN
-# define X_OUT rcx
-# define COUNT edx
+# define OP rcx
+# define X_OUT rdx
+# define COUNT r8d
#endif
endprologue
jc 9f
dec COUNT
jnz 0b
+ jmp 8f
// Failed to come up with a random value.
- mov eax, -1
+8: mov eax, -1
ret
// Success.