GC with realtime support

lib/system/timers.nim

@@ -0,0 +1,92 @@
+#
+#
+#            Nimrod's Runtime Library
+#        (c) Copyright 2012 Andreas Rumpf
+#
+#    See the file "copying.txt", included in this
+#    distribution, for details about the copyright.
+#
+
+## Timer support for the realtime GC. Based on
+## `<https://github.com/jckarter/clay/blob/master/compiler/src/hirestimer.cpp>`_
+
+type
+  TTicks = distinct int64
+  TNanos = int64
+
+when defined(windows):
+
+  proc QueryPerformanceCounter(res: var TTicks) {.
+    importc: "QueryPerformanceCounter", stdcall, dynlib: "kernel32".}
+  proc QueryPerformanceFrequency(res: var int64) {.
+    importc: "QueryPerformanceFrequency", stdcall, dynlib: "kernel32".}
+
+  proc getTicks(): TTicks {.inline.} =
+    QueryPerformanceCounter(result)
+
+  proc `-`(a, b: TTicks): TNanos =
+    var frequency: int64
+    QueryPerformanceFrequency(frequency)
+    var performanceCounterRate = 1000000000.0 / toFloat(frequency.int)
+
+    result = ((a.int64 - b.int64).int.toFloat * performanceCounterRate).TNanos
+
+elif defined(macosx):
+  type
+    TMachTimebaseInfoData {.pure, final, 
+        importc: "mach_timebase_info_data_t", 
+        header: "<mach/mach_time.h>".} = object
+      numer, denom: int32
+
+  proc mach_absolute_time(): int64 {.importc, header: "<mach/mach.h>".}
+  proc mach_timebase_info(info: var TMachTimebaseInfoData) {.importc,
+    header: "<mach/mach_time.h>".}
+
+  proc getTicks(): TTicks {.inline.} =
+    result = TTicks(mach_absolute_time())
+
+  proc `-`(a, b: TTicks): TNanos =
+    var timeBaseInfo: TMachTimebaseInfoData
+    mach_timebase_info(timeBaseInfo)
+    result = (a.int64 - b.int64)  * timeBaseInfo.numer div timeBaseInfo.denom
+
+elif defined(posixRealtime):
+  type
+    TClockid {.importc: "clockid_t", header: "<time.h>", final.} = object
+
+    TTimeSpec {.importc: "struct timespec", header: "<time.h>", 
+               final, pure.} = object ## struct timespec
+      tv_sec: int  ## Seconds. 
+      tv_nsec: int ## Nanoseconds. 
+
+  var
+    CLOCK_REALTIME {.importc: "CLOCK_REALTIME", header: "<time.h>".}: TClockid
+
+  proc clock_gettime(clkId: TClockid, tp: var TTimespec) {.
+    importc: "clock_gettime", header: "<time.h>".}
+
+  proc getTicks(): TTicks =
+    var t: TTimespec
+    clock_gettime(CLOCK_REALTIME, t)
+    result = TTicks(int64(t.tv_sec) * 1000000000'i64 + int64(t.tv_nsec))
+
+  proc `-`(a, b: TTicks): TNanos {.borrow.}
+
+else:
+  # fallback Posix implementation:  
+  type
+    Ttimeval {.importc: "struct timeval", header: "<sys/select.h>", 
+               final, pure.} = object ## struct timeval
+      tv_sec: int  ## Seconds. 
+      tv_usec: int ## Microseconds. 
+        
+  proc posix_gettimeofday(tp: var Ttimeval, unused: pointer = nil) {.
+    importc: "gettimeofday", header: "<sys/time.h>".}
+
+  proc getTicks(): TTicks =
+    var t: Ttimeval
+    posix_gettimeofday(t)
+    result = TTicks(int64(t.tv_sec) * 1000_000_000'i64 + 
+                    int64(t.tv_usec) * 1000'i64)
+
+  proc `-`(a, b: TTicks): TNanos {.borrow.}