Add arch-agnostic fls() fallback

[ust.git] / include / ust / processor.h

diff --git a/include/ust/processor.h b/include/ust/processor.h
index 867b140cce9b2d408f594f770ac688da86f5702c..6ee44ddde599f3bd8eb5e24d90295c800168e1be 100644 (file)
--- a/include/ust/processor.h
+++ b/include/ust/processor.h
@@ -20,10 +20,13 @@
 
 #include <stddef.h>
 #include <string.h>
+#include <urcu-bp.h>
 
 extern __thread long ust_reg_stack[500];
 extern volatile __thread long *ust_reg_stack_ptr;
 
+#define ____cacheline_aligned __attribute__((aligned(CAA_CACHE_LINE_SIZE)))
+
 #ifdef __i386
 
 struct registers {
@@ -211,9 +214,7 @@ static inline int fls(int x)
 
 #define _ASM_PTR ".long "
 
-#endif /* below is code for x86-64 */
-
-#ifdef __x86_64
+#elif defined(__x86_64)
 
 struct registers {
        int padding; /* 4 bytes */
@@ -290,7 +291,7 @@ static inline int fls(int x)
             /* Start TLS access of private reg stack pointer */ \
             ".byte 0x66\n\t" \
             "leaq ust_reg_stack_ptr@tlsgd(%%rip), %%rdi\n\t" \
-            ".word 0x6666\n\t" \
+            ".hword 0x6666\n\t" \
             "rex64\n\t" \
             "call __tls_get_addr@plt\n\t" \
             /* --- End TLS access */ \
@@ -302,7 +303,7 @@ static inline int fls(int x)
             /* Start TLS access of private reg stack */ \
             ".byte 0x66\n\t" \
             "leaq ust_reg_stack@tlsgd(%%rip), %%rdi\n\t" \
-            ".word 0x6666\n\t" \
+            ".hword 0x6666\n\t" \
             "rex64\n\t" \
             "call __tls_get_addr@plt\n\t" \
             /* --- End TLS access */ \
@@ -422,9 +423,7 @@ static inline int fls(int x)
 
 #define _ASM_PTR ".quad "
 
-#endif /* x86_64 */
-
-#ifdef __PPC__
+#elif defined(__PPC__)
 
 struct registers {
 };
@@ -444,6 +443,37 @@ static __inline__ int fls(unsigned int x)
 #define _ASM_PTR ".long "
 #define save_registers(a)
 
-#endif /* __PPC__ */
+#else /* arch-agnostic */
+
+static __inline__ int fls(unsigned int x)
+{
+       int r = 32;
+
+       if (!x)
+               return 0;
+       if (!(x & 0xFFFF0000U)) {
+               x <<= 16;
+               r -= 16;
+       }
+       if (!(x & 0xFF000000U)) {
+               x <<= 8;
+               r -= 8;
+       }
+       if (!(x & 0xF0000000U)) {
+               x <<= 4;
+               r -= 4;
+       }
+       if (!(x & 0xC0000000U)) {
+               x <<= 2;
+               r -= 2;
+       }
+       if (!(x & 0x80000000U)) {
+               x <<= 1;
+               r -= 1;
+       }
+       return r;
+}
+
+#endif
 
 #endif /* UST_PROCESSOR_H */