first steps to thread local heaps

lib/system/atomics.nim

@@ -0,0 +1,41 @@
+#
+#
+#            Nimrod's Runtime Library
+#        (c) Copyright 2011 Andreas Rumpf
+#
+#    See the file "copying.txt", included in this
+#    distribution, for details about the copyright.
+#
+
+## Atomic operations for Nimrod.
+
+when (defined(gcc) or defined(llvm_gcc)) and hasThreadSupport:
+  proc sync_add_and_fetch(p: var int, val: int): int {.
+    importc: "__sync_add_and_fetch", nodecl.}
+  proc sync_sub_and_fetch(p: var int, val: int): int {.
+    importc: "__sync_sub_and_fetch", nodecl.}
+elif defined(vcc) and hasThreadSupport:
+  proc sync_add_and_fetch(p: var int, val: int): int {.
+    importc: "NimXadd", nodecl.}
+else:
+  proc sync_add_and_fetch(p: var int, val: int): int {.inline.} =
+    inc(p, val)
+    result = p
+
+proc atomicInc(memLoc: var int, x: int): int =
+  when hasThreadSupport:
+    result = sync_add_and_fetch(memLoc, x)
+  else:
+    inc(memLoc, x)
+    result = memLoc
+  
+proc atomicDec(memLoc: var int, x: int): int =
+  when hasThreadSupport:
+    when defined(sync_sub_and_fetch):
+      result = sync_sub_and_fetch(memLoc, x)
+    else:
+      result = sync_add_and_fetch(memLoc, -x)
+  else:
+    dec(memLoc, x)
+    result = memLoc  
+