Add tasks for all the new languages

Task/Safe-addition/Nim/safe-addition.nim

@@ -0,0 +1,20 @@
+import posix, strutils
+
+proc `++`(a, b: float): tuple[lower, upper: float] =
+  let
+    a {.volatile.} = a
+    b {.volatile.} = b
+    orig = fegetround()
+  discard fesetround FE_DOWNWARD
+  result.lower = a + b
+  discard fesetround FE_UPWARD
+  result.upper = a + b
+  discard fesetround orig
+
+proc ff(a: float): string = a.formatFloat(ffDefault, 17)
+
+for x, y in [(1.0, 2.0), (0.1, 0.2), (1e100, 1e-100), (1e308, 1e308)].items:
+  let (d,u) = x ++ y
+  echo x.ff, " + ", y.ff, " ="
+  echo "    [", d.ff, ", ", u.ff, "]"
+  echo "    size ", (u - d).ff, "\n"

Task/Safe-addition/Phix/safe-addition.phix

@@ -0,0 +1,53 @@
+include builtins\VM\pFPU.e  -- :%down53 etc
+
+function safe_add(atom a, atom b)
+atom low,high
+    -- NB: be sure to restore the usual/default rounding!
+    #ilASM{
+        [32]
+            lea esi,[a]
+            call :%pLoadFlt
+            lea esi,[b]
+            call :%pLoadFlt
+            fld st0
+            call :%down53
+            fadd st0,st2
+            lea edi,[low]
+            call :%pStoreFlt
+            call :%up53
+            faddp
+            lea edi,[high]
+            call :%pStoreFlt
+            call :%near53       -- usual/default
+        [64]
+            lea rsi,[a]
+            call :%pLoadFlt
+            lea rsi,[b]
+            call :%pLoadFlt
+            fld st0
+            call :%down64
+            fadd st0,st2
+            lea rdi,[low]
+            call :%pStoreFlt
+            call :%up64
+            faddp
+            lea rdi,[high]
+            call :%pStoreFlt
+            call :%near64   -- usual/default
+        []
+          }
+    return {low,high}
+end function
+
+constant nums = {{1, 2},
+                 {0.1, 0.2},
+                 {1e100, 1e-100},
+                 {1e308, 1e308}}
+
+    for i=1 to length(nums) do
+        atom {a,b} = nums[i]
+        atom {low,high} = safe_add(a,b)
+        printf(1,"%.16g + %.16g =\n", {a, b});
+        printf(1,"    [%.16g, %.16g]\n", {low, high});
+        printf(1,"    size %.16g\n\n", high - low);
+    end for