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我有以下(有点低效)代码:

\ RNG support

VARIABLE seed

: rand ( -- random )
seed @
DUP 13 LSHIFT XOR
DUP 17 RSHIFT XOR
DUP 5 LSHIFT XOR
DUP seed ! ;

\ Checker for number of set bits

: clear-lsb ( u -- u )
DUP 1- AND ;

: under++ ( u x -- u++ x )
SWAP 1+ SWAP ;

: ones-rec ( c u -- c u | c )
?DUP ( c 0 | c u u )
0<> IF EXIT ( c | c u )
THEN under++ clear-lsb RECURSE ;

: ones-rec ( c u -- c u | c )
?DUP IF
under++ clear-lsb
RECURSE
THEN ;

: ones ( u -- n )
0 SWAP ones-rec ;

\ Makes a random number with n set bits

: rand-n-bits ( n -- random )
rand ( n random )
OVER SWAP ( n n random )
ones ( n n bits )
= ( n f )
IF EXIT
THEN RECURSE ;

据我了解,RECURSEs inrand-n-bitsones-recshould 都是正确的尾调用。然而,当我要求 Gforth 做 时10 rand-n-bits,我溢出了返回堆栈。Gforth 是否没有优化正确的尾调用,或者我只是没有正确执行此操作?

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