xnu-1228.12.14.tar.gz

[apple/xnu.git] / osfmk / i386 / commpage / commpage_gettimeofday.s

diff --git a/osfmk/i386/commpage/commpage_gettimeofday.s b/osfmk/i386/commpage/commpage_gettimeofday.s
index 34c4f9bee7cdb8e68f032454f4e2ee76b7000b56..a50dd5410402bd7eb871d5b95c1d4c13c11bc323 100644 (file)
--- a/osfmk/i386/commpage/commpage_gettimeofday.s
+++ b/osfmk/i386/commpage/commpage_gettimeofday.s
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2003-2006 Apple Computer, Inc. All rights reserved.
+ * Copyright (c) 2003-2007 Apple Inc. All rights reserved.
  *
  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
  * 
@@ -40,29 +40,25 @@ Lgettimeofday:
        push    %ebp
        mov     %esp,%ebp
        push    %esi
-       push    %edi
        push    %ebx
 
 0:
-       cmp     $0,_COMM_PAGE_TIMEENABLE
-       je      4f
-       mov     _COMM_PAGE_TIMEBASE,%esi
-       mov     _COMM_PAGE_TIMEBASE+4,%edi
-       mov     _COMM_PAGE_TIMESTAMP,%ebx
+       movl    _COMM_PAGE_GTOD_GENERATION,%esi /* get generation (0 if disabled) */
+       testl   %esi,%esi                       /* disabled? */
+       jz      4f
 
        mov     $ _COMM_PAGE_NANOTIME,%eax
-       call    *%eax           /* get ns in %edx:%eax */
+       call    *%eax                           /* get ns in %edx:%eax */
 
-       cmp     _COMM_PAGE_TIMEBASE,%esi
-       jne     0b
-       cmp     _COMM_PAGE_TIMEBASE+4,%edi
-       jne     0b
-       cmp     $0,_COMM_PAGE_TIMEENABLE
-       je      4f
        
+       sub     _COMM_PAGE_GTOD_NS_BASE,%eax
+       sbb     _COMM_PAGE_GTOD_NS_BASE+4,%edx
+       mov     _COMM_PAGE_GTOD_SEC_BASE,%ebx   /* load all the data before checking generation */
        mov     $ NSEC_PER_SEC,%ecx
-       sub     %esi,%eax
-       sbb     %edi,%edx
+       
+       cmpl    _COMM_PAGE_GTOD_GENERATION,%esi /* has time data changed out from under us? */
+       jne     0b
+       
        div     %ecx
        add     %eax,%ebx
 
@@ -78,7 +74,6 @@ Lgettimeofday:
 
 3:
        pop     %ebx
-       pop     %edi
        pop     %esi
        pop     %ebp
        ret
@@ -97,21 +92,21 @@ Lgettimeofday_64:                   // %rdi = ptr to timeval
        pushq   %rbp                    // set up a frame for backtraces
        movq    %rsp,%rbp
        movq    %rdi,%r9                // save ptr to timeval
-       movq    $_COMM_PAGE_32_TO_64(_COMM_PAGE_TIMEBASE),%r10
+       movq    $_COMM_PAGE_32_TO_64(_COMM_PAGE_TIME_DATA_START),%r10
 0:
-       cmpl    $0,_TIMEENABLE(%r10)    // is data valid? (test _COMM_PAGE_TIMEENABLE)
-       jz      4f                      // no
-       movq    _TIMEBASE(%r10),%r11    // get _COMM_PAGE_TIMEBASE
+       movl    _GTOD_GENERATION(%r10),%r11d    // get generation (0 if disabled)
+       testl   %r11d,%r11d             // disabled?
+       jz      4f
+       
        movq    $_COMM_PAGE_32_TO_64(_COMM_PAGE_NANOTIME),%rax
        call    *%rax                   // get %rax <- nanotime(), preserving %r9, %r10 and %r11
-       movl    _TIMESTAMP(%r10),%r8d   // get _COMM_PAGE_TIMESTAMP
-       cmpq    _TIMEBASE(%r10),%r11    // has _COMM_PAGE_TIMEBASE changed?
-       jne     0b                      // loop until we have consistent data
-       cmpl    $0,_TIMEENABLE(%r10)    // is data valid? (test _COMM_PAGE_TIMEENABLE)
-       jz      4f                      // no
+       
+       movl    _GTOD_SEC_BASE(%r10),%r8d       // get _COMM_PAGE_TIMESTAMP
+       subq    _GTOD_NS_BASE(%r10),%rax        // generate nanoseconds since timestamp
+       cmpl    _GTOD_GENERATION(%r10),%r11d    // has data changed out from under us?
+       jne     0b
        
        movl    $ NSEC_PER_SEC,%ecx
-       subq    %r11,%rax               // generate nanoseconds since timestamp
        movq    %rax,%rdx
        shrq    $32,%rdx                // get high half of delta in %edx
        divl    %ecx                    // %eax <- seconds since timestamp, %edx <- nanoseconds