xnu-1228.9.59.tar.gz

[apple/xnu.git] / osfmk / i386 / rtclock.h

diff --git a/osfmk/i386/rtclock.h b/osfmk/i386/rtclock.h
index 904b387861d310c0b5f0191477abeda04bbdb923..e3ea716d46e088327768ee2308dd9e78d26c8ae1 100644 (file)
--- a/osfmk/i386/rtclock.h
+++ b/osfmk/i386/rtclock.h
@@ -40,8 +40,90 @@
 #ifndef _I386_RTCLOCK_H_
 #define _I386_RTCLOCK_H_
 
 #ifndef _I386_RTCLOCK_H_
 #define _I386_RTCLOCK_H_
 

+#ifndef ASSEMBLER
+typedef struct rtc_nanotime {
+       uint64_t        tsc_base;               /* timestamp */
+       uint64_t        ns_base;                /* nanoseconds */
+       uint32_t        scale;                  /* tsc -> nanosec multiplier */
+       uint32_t        shift;                  /* tsc -> nanosec shift/div */
+                                               /* shift is overloaded with
+                                                * lower 32bits of tsc_freq
+                                                * on slower machines (SLOW_TSC_THRESHOLD) */
+       uint32_t        generation;             /* 0 == being updated */
+       uint32_t        spare1;
+} rtc_nanotime_t;
+

 #include <kern/etimer.h>
 
 struct cpu_data;
 
 #include <kern/etimer.h>
 
 struct cpu_data;
 

+extern void    _rtc_nanotime_store(
+                       uint64_t        tsc,
+                       uint64_t        nsec,
+                       uint32_t        scale,
+                       uint32_t        shift,
+                       rtc_nanotime_t  *dst);
+
+extern uint64_t        _rtc_nanotime_read(
+                       rtc_nanotime_t  *rntp,
+                       int             slow);
+
+extern rtc_nanotime_t  rtc_nanotime_info;
+#endif
+
+#define        SLOW_TSC_THRESHOLD      1000067800      /* TSC is too slow for regular nanotime() algorithm */
+
+#if defined(__i386__)
+/*
+ * Assembly snippet included in exception handlers and rtc_nanotime_read()
+ * %edi points to nanotime info struct
+ * %edx:%eax returns nanotime
+ */
+#define RTC_NANOTIME_READ_FAST()                                         \
+0:     movl    RNT_GENERATION(%edi),%esi       /* being updated? */    ; \
+       testl   %esi,%esi                                               ; \
+       jz      0b                              /* wait until done */   ; \
+       rdtsc                                                           ; \
+       lfence                                                          ; \
+       subl    RNT_TSC_BASE(%edi),%eax                                 ; \
+       sbbl    RNT_TSC_BASE+4(%edi),%edx       /* tsc - tsc_base */    ; \
+       movl    RNT_SCALE(%edi),%ecx            /* * scale factor */    ; \
+       movl    %edx,%ebx                                               ; \
+       mull    %ecx                                                    ; \
+       movl    %ebx,%eax                                               ; \
+       movl    %edx,%ebx                                               ; \
+       mull    %ecx                                                    ; \
+       addl    %ebx,%eax                                               ; \
+       adcl    $0,%edx                                                 ; \
+       addl    RNT_NS_BASE(%edi),%eax          /* + ns_base */         ; \
+       adcl    RNT_NS_BASE+4(%edi),%edx                                ; \
+       cmpl    RNT_GENERATION(%edi),%esi       /* check for update */  ; \
+       jne     0b                              /* do it all again */
+
+#elif defined(__x86_64__)
+
+/*
+ * Assembly snippet included in exception handlers and rtc_nanotime_read()
+ * %rdi points to nanotime info struct.
+ * %rax returns nanotime
+ */
+#define RTC_NANOTIME_READ_FAST()                                         \
+0:     movl    RNT_GENERATION(%rdi),%esi                               ; \
+       test    %esi,%esi                       /* info updating? */    ; \
+       jz      0b                              /* - wait if so */      ; \
+       rdtsc                                                           ; \
+       lfence                                                          ; \
+       shlq    $32,%rdx                                                ; \
+       orq     %rdx,%rax                       /* %rax := tsc */       ; \
+       subq    RNT_TSC_BASE(%rdi),%rax         /* tsc - tsc_base */    ; \
+       xorq    %rcx,%rcx                                               ; \
+       movl    RNT_SCALE(%rdi),%ecx                                    ; \
+       mulq    %rcx                            /* delta * scale */     ; \
+       shrdq   $32,%rdx,%rax                   /* %rdx:%rax >>= 32 */  ; \
+       addq    RNT_NS_BASE(%rdi),%rax          /* add ns_base */       ; \
+       cmpl    RNT_GENERATION(%rdi),%esi       /* repeat if changed */ ; \
+       jne     0b
+
+#endif
+

 #endif /* _I386_RTCLOCK_H_ */
 #endif /* _I386_RTCLOCK_H_ */