X-Git-Url: https://git.distorted.org.uk/~mdw/catacomb/blobdiff_plain/a90d420cbe87490c844ae422c966e746d3134b07..6c0946ef1f1fa9b75b8c6d65ea0554ff4e1ec4eb:/rand/rand-x86ish.S

diff --git a/rand/rand-x86ish.S b/rand/rand-x86ish.S
index 61de2b84..b91a9373 100644
--- a/rand/rand-x86ish.S
+++ b/rand/rand-x86ish.S
@@ -37,6 +37,17 @@
 ///--------------------------------------------------------------------------
 /// Quick random generation.
 
+// Common register allocation.
+#if CPUFAM_X86
+#  define COUNT ecx
+#endif
+#if CPUFAM_AMD64 && ABI_SYSV
+#  define COUNT ecx
+#endif
+#if CPUFAM_AMD64 && ABI_WIN
+#  define COUNT r8d
+#endif
+
 FUNC(rand_quick_x86ish_rdrand)
 	// Enter with a pointer to the random context in the first argument.
 	// Return zero on success, or -1 on error.
@@ -44,15 +55,12 @@ FUNC(rand_quick_x86ish_rdrand)
 #if CPUFAM_X86
 	mov	edx, [SP + 4]
 	stalloc	28
-#  define COUNT ecx
 #endif
 #if CPUFAM_AMD64 && ABI_SYSV
 	stalloc	8
-#  define COUNT ecx
 #endif
 #if CPUFAM_AMD64 && ABI_WIN
 	stalloc	40
-#  define COUNT r8d
 #endif
   endprologue
 
@@ -66,6 +74,34 @@ FUNC(rand_quick_x86ish_rdrand)
 	// Failed.
 	mov	eax, -1
 	jmp	9f
+ENDFUNC
+
+FUNC(rand_quick_x86ish_rdseed)
+	// Enter with a pointer to the random context in the first argument.
+	// Return zero on success, or -1 on error.
+
+#if CPUFAM_X86
+	mov	edx, [SP + 4]
+	stalloc	28
+#endif
+#if CPUFAM_AMD64 && ABI_SYSV
+	stalloc	8
+#endif
+#if CPUFAM_AMD64 && ABI_WIN
+	stalloc	40
+#endif
+  endprologue
+
+	// Try to fetch a random number.
+	mov	COUNT, 16
+0:	rdseed	AX
+	jc	1f
+	dec	COUNT
+	jnz	0b
+
+	// Failed.
+	mov	eax, -1
+	jmp	9f
 
 	// Success.
 1:
@@ -106,4 +142,6 @@ FUNC(rand_quick_x86ish_rdrand)
 	ret
 ENDFUNC
 
+#undef COUNT
+
 ///----- That's all, folks --------------------------------------------------