92 lines
No EOL
2.2 KiB
Racket
92 lines
No EOL
2.2 KiB
Racket
#lang racket
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(require rnrs
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rhs/rhs
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rnrs/bytevectors-6
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rnrs/io/ports-6)
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(provide (all-defined-out)
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put-bytevector
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get-bytevector-n
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bytevector-length)
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;; JBC-2014 -- looks like all of these have
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;; equivalents in Racket...
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;; bytevector -> (port -> any) -> any
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(define with-input-from-bytevector
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(lambda (b f)
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(let* ((p (open-bytevector-input-port b))
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(r (f p)))
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(close-port p)
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r)))
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;; bytevector -> int -> int -> bytevector
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(define bytevector-section
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(lambda (v l r)
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(let* ((n (- r l))
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(w (make-bytevector n 0)))
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(bytevector-copy! v l w 0 n)
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w)))
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;; bytevector -> byte -> int
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(define bytevector-find-index
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(lambda (v x)
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(letrec ((f (lambda (i)
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(if (= (bytevector-u8-ref v i) x)
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i
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(f (+ i 1))))))
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(f 0))))
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;; Tree bytevector -> bytevector
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(define flatten-bytevectors
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(lambda (t)
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(let* ((l (flatten t))
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(n (map1 bytevector-length l))
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(m (sum n))
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(v (make-bytevector m)))
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(let loop ((i 0)
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(l l)
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(n n))
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(if (null? l)
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v
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(let ((l0 (car l))
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(n0 (car n)))
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(bytevector-copy! l0 0 v i n0)
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(loop (+ i n0) (cdr l) (cdr n))))))))
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;; number a => (bytevector -> int -> a -> ()) -> int -> a
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(define bytevector-make-and-set1
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(lambda (f k n)
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(let ((v (make-bytevector k 0)))
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(f v 0 n)
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v)))
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;; number a => (bytevector -> int -> a -> ()) -> int -> a
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(define bytevector-make-and-set
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(lambda (f k n)
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(let ((v (make-bytevector k 0)))
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(f v 0 n (endianness big))
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v)))
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(module+ test
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(require rackunit)
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(test-begin
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(let [(long-vec (bytes 10 20 30 40 50))]
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(check-equal? (bytevector-section long-vec 0 2)
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(bytes 10 20))
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(check-equal? (bytevector-section long-vec 0 (bytes-length long-vec))
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long-vec)
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;; bytevector-section is equivalent ot subbytes
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(check-equal? (bytevector-section long-vec 1 3)
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(subbytes long-vec 1 3))
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; check if exceding limits raises exception
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(check-exn exn:fail? (λ () (bytevector-section long-vec 0 30)))
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(check-exn exn:fail? (λ () (bytevector-section long-vec -1 3)))
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)
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)
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) |