cmake - fix rtcd detection on x86 non windows

Signed-off-by: Mark Harris <mark.hsj@gmail.com>

1 files changed, 31 insertions, 0 deletions

diff --git a/cmake/cpu_info_by_asm.c b/cmake/cpu_info_by_asm.c
new file mode 100644
index 00000000..1a70a815
--- /dev/null
+++ b/cmake/cpu_info_by_asm.c
@@ -0,0 +1,31 @@
+#include <stdio.h>
+int main() {
+    unsigned int CPUInfo0;
+    unsigned int CPUInfo1;
+    unsigned int CPUInfo2;
+    unsigned int CPUInfo3;
+    unsigned int InfoType;
+#if defined(__i386__) && defined(__PIC__)
+/* %ebx is PIC register in 32-bit, so mustn't clobber it. */
+    __asm__ __volatile__ (
+        "xchg %%ebx, %1\n"
+        "cpuid\n"
+        "xchg %%ebx, %1\n":
+        "=a" (CPUInfo0),
+        "=r" (CPUInfo1),
+        "=c" (CPUInfo2),
+        "=d" (CPUInfo3) :
+        "0" (InfoType), "2" (0)
+    );
+#else
+    __asm__ __volatile__ (
+        "cpuid":
+        "=a" (CPUInfo0),
+        "=b" (CPUInfo1),
+        "=c" (CPUInfo2),
+        "=d" (CPUInfo3) :
+        "0" (InfoType), "2" (0)
+    );
+#endif
+    return 0;
+}