unwindLib.UNWIND_ONCE

STRUCTURE

SYNOPSIS

Basic conversion for parallel unwinding of equations defining wire values in a standard device specification.

LIBRARY

unwind

DESCRIPTION

UNWIND_ONCE_CONV p tm unwinds the conjunction tm using the equations selected by the predicate p. tm should be a conjunction, equivalent under associative-commutative reordering to:

   t1 /\ t2 /\ ... /\ tn

p is used to partition the terms ti for 1 <= i <= n into two disjoint sets:

   REW = {{ti | p ti}}
   OBJ = {{ti | ~p ti}}

The terms ti for which p is true are then used as a set of rewrite rules (thus they should be equations) to do a single top-down parallel rewrite of the remaining terms. The rewritten terms take the place of the original terms in the input conjunction. For example, if tm is:

   t1 /\ t2 /\ t3 /\ t4

and REW = {{t1,t3}} then the result is:

   |- t1 /\ t2 /\ t3 /\ t4 = t1 /\ t2' /\ t3 /\ t4'

where ti' is ti rewritten with the equations REW.

FAILURE

Never fails.

EXAMPLE

#UNWIND_ONCE_CONV (\tm. mem (line_name tm) [`l1`;`l2`])
# "(!(x:num). l1 x = (l2 x) - 1) /\
#  (!x. f x = (l2 (x+1)) + (l1 (x+2))) /\
#  (!x. l2 x = 7)";;
|- (!x. l1 x = (l2 x) - 1) /\
   (!x. f x = (l2(x + 1)) + (l1(x + 2))) /\
   (!x. l2 x = 7) =
   (!x. l1 x = (l2 x) - 1) /\
   (!x. f x = 7 + ((l2(x + 2)) - 1)) /\
   (!x. l2 x = 7)

SEEALSO

UNWIND_CONV, UNWIND_ALL_BUT_CONV, UNWIND_AUTO_CONV, UNWIND_ALL_BUT_RIGHT_RULE, UNWIND_AUTO_RIGHT_RULE