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Faster flonum operations using flbit-field #116

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cd459c6
Faster flonum operations using flbit-field
pavpanchekha Jan 19, 2026
898aa2f
Types
pavpanchekha Jan 19, 2026
197035e
Faster flonums-between
pavpanchekha Jan 19, 2026
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34 changes: 22 additions & 12 deletions math-lib/math/private/flonum/flonum-bits.rkt
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,8 @@

(require racket/flonum
racket/performance-hint)
(require/typed racket/flonum
[flbit-field (-> Flonum Byte Byte Natural)])

(provide flonum->bit-field bit-field->flonum
flonum->fields fields->flonum
Expand All @@ -12,8 +14,7 @@

(: flonum->bit-field (Flonum -> Natural))
(define (flonum->bit-field x)
(assert (integer-bytes->integer (real->floating-point-bytes x (ann 8 8)) #f)
exact-nonnegative-integer?))
(flbit-field x 0 64))

(: bit-field->flonum (Integer -> Flonum))
(define (bit-field->flonum i)
Expand All @@ -30,10 +31,9 @@

(: flonum->fields (Flonum -> (Values (U 0 1) Index Natural)))
(define (flonum->fields x)
(define n (flonum->bit-field x))
(values (if (zero? (bitwise-bit-field n 63 64)) 0 1)
(assert (bitwise-bit-field n 52 63) index?)
(bitwise-bit-field n 0 52)))
(values (if (zero? (flbit-field x 63 64)) 0 1)
(assert (flbit-field x 52 63) index?)
(flbit-field x 0 52)))

(: fields->flonum (Integer Integer Integer -> Flonum))
(define (fields->flonum s e m)
Expand Down Expand Up @@ -66,8 +66,8 @@

(: flonum->ordinal (Flonum -> Integer))
(define (flonum->ordinal x)
(cond [(x . fl< . 0.0) (- (flonum->bit-field (fl- 0.0 x)))]
[else (flonum->bit-field (flabs x))])) ; abs for -0.0
(cond [(x . fl< . 0.0) (- (flbit-field (fl- 0.0 x) 0 64))]
[else (flbit-field (flabs x) 0 64)])) ; abs for -0.0

(: ordinal->flonum (Integer -> Flonum))
(define (ordinal->flonum i)
Expand Down Expand Up @@ -99,11 +99,21 @@
(: flprev (Flonum -> Flonum))
(define (flprev x) (flstep x -1))

(: flonums-between (Flonum Flonum -> Integer))
(define (flonums-between x y)
(- (flonum->ordinal y) (flonum->ordinal x)))

) ; begin-encourage-inline

(: flonum->chunks (-> Flonum (Values Integer Integer)))
(define (flonum->chunks x)
(define neg? (fl< x 0.0))
(define ax (flabs x))
(if neg?
(values (- (flbit-field ax 0 32)) (- (flbit-field ax 32 64)))
(values (flbit-field ax 0 32) (flbit-field ax 32 64))))

(: flonums-between (Flonum Flonum -> Integer))
(define (flonums-between x y)
(define-values (xlo xhi) (flonum->chunks x))
(define-values (ylo yhi) (flonum->chunks y))
(+ (arithmetic-shift (- yhi xhi) 32) (- ylo xlo)))

(: flulp (Flonum -> (U Flonum-Nan Nonnegative-Flonum)))
(define (flulp x)
Expand Down
6 changes: 6 additions & 0 deletions math-test/math/tests/flonum-tests.rkt
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Original file line number Diff line number Diff line change
Expand Up @@ -144,6 +144,12 @@
(check-equal? (flulp-error x (flnext x)) 1.0
(format "x = ~a" x)))

(for ([_ (in-range 1000)])
(define x (ordinal->flonum (random-integer (flonum->ordinal -inf.0) (flonum->ordinal +inf.0))))
(define y (ordinal->flonum (random-integer (flonum->ordinal -inf.0) (flonum->ordinal +inf.0))))
(check-equal? (flonums-between x y)
(- (flonum->ordinal y) (flonum->ordinal x))))

;; ===================================================================================================
;; fllog2

Expand Down