FromInt.aplf

 r←FromInt n;bits;pos
 ⍝ Create a bignum from an integer

 ⍝ Check that the type is one of the integer types
 :If ~(⎕DR n)∊11 83 163 323
     ⎕SIGNAL 11
 :EndIf

 r←(2∘⊥⍣¯1)|n

 :If ⊃r
     r←0,r
 :EndIf

 :If n<0
     r←Neg r
 :EndIf