diff --git a/lib/impure/fenv.nim b/lib/impure/fenv.nim
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+#
+#
+#            Nimrod's Runtime Library
+#        (c) Copyright 2014 Andreas Rumpf
+#
+#    See the file "copying.txt", included in this
+#    distribution, for details about the copyright.
+#
+
+## Floating-point environment. Handling of floating-point rounding and
+## exceptions (overflow, zero-devide, etc.).
+
+{.deadCodeElim:on.}
+
+when defined(Posix) and not defined(haiku):
+  {.passl: "-lm".}
+
+var
+  FE_DIVBYZERO* {.importc, header: "<fenv.h>".}: cint
+    ## division by zero
+  FE_INEXACT* {.importc, header: "<fenv.h>".}: cint
+    ## inexact result
+  FE_INVALID* {.importc, header: "<fenv.h>".}: cint
+    ## invalid operation
+  FE_OVERFLOW* {.importc, header: "<fenv.h>".}: cint
+    ## result not representable due to overflow
+  FE_UNDERFLOW* {.importc, header: "<fenv.h>".}: cint
+    ## result not representable due to underflow
+  FE_ALL_EXCEPT* {.importc, header: "<fenv.h>".}: cint
+    ## bitwise OR of all supported exceptions
+  FE_DOWNWARD* {.importc, header: "<fenv.h>".}: cint
+    ## round toward -Inf
+  FE_TONEAREST* {.importc, header: "<fenv.h>".}: cint
+    ## round to nearest
+  FE_TOWARDZERO* {.importc, header: "<fenv.h>".}: cint
+    ## round toward 0
+  FE_UPWARD* {.importc, header: "<fenv.h>".}: cint
+    ## round toward +Inf
+  FE_DFL_ENV* {.importc, header: "<fenv.h>".}: cint
+    ## macro of type pointer to fenv_t to be used as the argument
+    ## to functions taking an argument of type fenv_t; in this
+    ## case the default environment will be used
+
+type
+  TFloatClass* = enum ## describes the class a floating point value belongs to.
+                      ## This is the type that is returned by `classify`.
+    fcNormal,    ## value is an ordinary nonzero floating point value
+    fcSubnormal, ## value is a subnormal (a very small) floating point value
+    fcZero,      ## value is zero
+    fcNegZero,   ## value is the negative zero
+    fcNan,       ## value is Not-A-Number (NAN)
+    fcInf,       ## value is positive infinity
+    fcNegInf     ## value is negative infinity
+
+  Tfenv* {.importc: "fenv_t", header: "<fenv.h>", final, pure.} =
+    object ## Represents the entire floating-point environment. The
+           ## floating-point environment refers collectively to any
+           ## floating-point status flags and control modes supported
+           ## by the implementation.
+  Tfexcept* {.importc: "fexcept_t", header: "<fenv.h>", final, pure.} =
+    object ## Represents the floating-point status flags collectively,
+           ## including any status the implementation associates with the
+           ## flags. A floating-point status flag is a system variable
+           ## whose value is set (but never cleared) when a floating-point
+           ## exception is raised, which occurs as a side effect of
+           ## exceptional floating-point arithmetic to provide auxiliary
+           ## information. A floating-point control mode is a system variable
+           ## whose value may be set by the user to affect the subsequent
+           ## behavior of floating-point arithmetic.
+
+proc feclearexcept*(excepts: cint): cint {.importc, header: "<fenv.h>".}
+  ## Clear the supported exceptions represented by `excepts`.
+
+proc fegetexceptflag*(flagp: ptr Tfexcept, excepts: cint): cint {.
+  importc, header: "<fenv.h>".}
+  ## Store implementation-defined representation of the exception flags
+  ## indicated by `excepts` in the object pointed to by `flagp`.
+
+proc feraiseexcept*(excepts: cint): cint {.importc, header: "<fenv.h>".}
+  ## Raise the supported exceptions represented by `excepts`.
+
+proc fesetexceptflag*(flagp: ptr Tfexcept, excepts: cint): cint {.
+  importc, header: "<fenv.h>".}
+  ## Set complete status for exceptions indicated by `excepts` according to
+  ## the representation in the object pointed to by `flagp`.
+
+proc fetestexcept*(excepts: cint): cint {.importc, header: "<fenv.h>".}
+  ## Determine which of subset of the exceptions specified by `excepts` are
+  ## currently set.
+
+proc fegetround*(): cint {.importc, header: "<fenv.h>".}
+  ## Get current rounding direction.
+
+proc fesetround*(roundingDirection: cint): cint {.importc, header: "<fenv.h>".}
+  ## Establish the rounding direction represented by `roundingDirection`.
+
+proc fegetenv*(envp: ptr Tfenv): cint {.importc, header: "<fenv.h>".}
+  ## Store the current floating-point environment in the object pointed
+  ## to by `envp`.
+
+proc feholdexcept*(envp: ptr Tfenv): cint {.importc, header: "<fenv.h>".}
+  ## Save the current environment in the object pointed to by `envp`, clear
+  ## exception flags and install a non-stop mode (if available) for all
+  ## exceptions.
+
+proc fesetenv*(a1: ptr Tfenv): cint {.importc, header: "<fenv.h>".}
+  ## Establish the floating-point environment represented by the object
+  ## pointed to by `envp`.
+
+proc feupdateenv*(envp: ptr Tfenv): cint {.importc, header: "<fenv.h>".}
+  ## Save current exceptions in temporary storage, install environment
+  ## represented by object pointed to by `envp` and raise exceptions
+  ## according to saved exceptions.