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Avoid needless allocation in read-bytevector! #950

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merged 4 commits into from
Mar 18, 2024
Merged

Avoid needless allocation in read-bytevector! #950

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d0e6dc7
Avoid needless allocation in read-bytevector!
wasamasa Mar 17, 2024
1b1e8b3
Correct read-bytevector logic for small reads
wasamasa Mar 18, 2024
c837c71
Correct let to let*
wasamasa Mar 18, 2024
0fd351e
Fix read-bytevector logic
wasamasa Mar 18, 2024
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39 changes: 17 additions & 22 deletions lib/scheme/extras.scm
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Original file line number Diff line number Diff line change
Expand Up @@ -134,37 +134,32 @@
(define (read-bytevector n . o)
(if (zero? n)
#u8()
(let ((in (if (pair? o) (car o) (current-input-port)))
(res (make-bytevector n)))
(let lp ((i 0))
(if (>= i n)
res
(let ((x (read-u8 in)))
(cond ((eof-object? x)
(if (zero? i) x (subbytes res 0 i)))
(else
(bytevector-u8-set! res i x)
(lp (+ i 1))))))))))
(let* ((in (if (pair? o) (car o) (current-input-port)))
(vec (make-bytevector n))
(res (read-bytevector! vec in)))
(cond ((eof-object? res) res)
((< res n) (subbytes vec 0 res))
(else vec)))))

(define (read-bytevector! vec . o)
(let* ((in (if (pair? o) (car o) (current-input-port)))
(o (if (pair? o) (cdr o) o))
(start (if (pair? o) (car o) 0))
(end (if (and (pair? o) (pair? (cdr o)))
(cadr o)
(bytevector-length vec))))
(bytevector-length vec)))
(n (- end start)))
(if (>= start end)
0
(let ((res (read-bytevector (- end start) in)))
(cond
((eof-object? res)
res)
(else
(let ((len (bytevector-length res)))
(do ((i 0 (+ i 1)))
((>= i len) len)
(bytevector-u8-set! vec (+ i start) (bytevector-u8-ref res i))
))))))))
(let lp ((i 0))
(if (>= i n)
i
(let ((x (read-u8 in)))
(cond ((eof-object? x)
(if (zero? i) x i))
(else
(bytevector-u8-set! vec (+ i start) x)
(lp (+ i 1))))))))))

(define (write-bytevector vec . o)
(let* ((out (if (pair? o) (car o) (current-output-port)))
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