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document integer->integer-bytes and integer-bytes->integer change

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This commit is contained in:
Matthew Flatt 2017-07-28 09:51:15 -06:00
parent 8ee5d18107
commit 94b9b8f4dd
2 changed files with 23 additions and 10 deletions
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22
pkgs/racket-doc/scribblings/reference/numbers.scrbl
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@ -1087,17 +1087,19 @@ padded with trailing zeros if necessary).
Converts the machine-format number encoded in @racket[bstr] to an
exact integer. The @racket[start] and @racket[end] arguments specify
the substring to decode, where @racket[(- end start)] must be
the substring to decode, where @racket[(- end start)] must be @racket[1],
@racket[2], @racket[4], or @racket[8]. If @racket[signed?] is true,
then the bytes are decoded as a two's-complement number, otherwise it
is decoded as an unsigned integer. If @racket[big-endian?] is true,
then the first character's ASCII value provides the most significant
eight bits of the number, otherwise the first character provides the
least-significant eight bits, and so on.}
then the first byte's value provides the most significant
eight bits of the number, otherwise the first byte provides the
least-significant eight bits, and so on.
@history[#:changed "6.10.0.1" @elem{Added support for decoding a 1-byte string.}]}
@defproc[(integer->integer-bytes [n exact-integer?]
[size-n (or/c 2 4 8)]
[size-n (or/c 1 2 4 8)]
[signed? any/c]
[big-endian? any/c (system-big-endian?)]
[dest-bstr (and/c bytes? (not/c immutable?))
@ -1106,12 +1108,12 @@ least-significant eight bits, and so on.}
bytes?]{
Converts the exact integer @racket[n] to a machine-format number
encoded in a byte string of length @racket[size-n], which must be
encoded in a byte string of length @racket[size-n], which must be @racket[1],
@racket[2], @racket[4], or @racket[8]. If @racket[signed?] is true,
then the number is encoded as two's complement, otherwise it is
encoded as an unsigned bit stream. If @racket[big-endian?] is true,
then the most significant eight bits of the number are encoded in the
first character of the resulting byte string, otherwise the
first byte of the resulting byte string, otherwise the
least-significant bits are encoded in the first byte, and so on.
The @racket[dest-bstr] argument must be a mutable byte string of
@ -1119,9 +1121,11 @@ length @racket[size-n]. The encoding of @racket[n] is written into
@racket[dest-bstr] starting at offset @racket[start], and
@racket[dest-bstr] is returned as the result.
If @racket[n] cannot be encoded in a string of the requested size and
If @racket[n] cannot be encoded in a byte string of the requested size and
format, the @exnraise[exn:fail:contract]. If @racket[dest-bstr] is not
of length @racket[size-n], the @exnraise[exn:fail:contract].}
of length @racket[size-n], the @exnraise[exn:fail:contract].
@history[#:changed "6.10.0.1" @elem{Added support for encoding a 1-byte value.}]}
@defproc[(floating-point-bytes->real [bstr bytes?]

11
pkgs/racket-test-core/tests/racket/number.rktl
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@ -2935,7 +2935,9 @@
(test #x22 integer-bytes->integer (bytes #x22) #f)
(test #xFE integer-bytes->integer (bytes #xFE) #f)
(test (- #x7E) integer-bytes->integer (bytes #x82) #t)
(test -1 integer-bytes->integer (bytes #xFF) #t)
(test 255 integer-bytes->integer (bytes #xFF) #f)
(test 0 integer-bytes->integer #"\0\0" #t)
(test -1 integer-bytes->integer #"\377\377" #t)
(test 65535 integer-bytes->integer #"\377\377" #f)
@ -3021,6 +3023,9 @@
(test (bytes #x22) integer->integer-bytes #x22 1 #t)
(test (bytes #xFE) integer->integer-bytes #xFE 1 #f)
(test (bytes #x82) integer->integer-bytes (- #x7E) 1 #t)
(test #"\377" integer->integer-bytes -1 1 #t)
(test #"\200" integer->integer-bytes -128 1 #t)
(test #"\377" integer->integer-bytes 255 1 #f)
(test #"\0\0" integer->integer-bytes 0 2 #t)
(test #"\377\377" integer->integer-bytes -1 2 #t)
@ -3091,6 +3096,10 @@
(err/rt-test (integer->integer-bytes 10 20 #t))
(err/rt-test (integer->integer-bytes 10 2 #t #t 'ack))
(err/rt-test (integer->integer-bytes 10 2 #t #t #"ack")) ; <-- immutable string
(err/rt-test (integer->integer-bytes 256 1 #t) exn:application:mismatch?)
(err/rt-test (integer->integer-bytes -129 1 #t) exn:application:mismatch?)
(err/rt-test (integer->integer-bytes 257 1 #f) exn:application:mismatch?)
(err/rt-test (integer->integer-bytes -1 1 #f) exn:application:mismatch?)
(err/rt-test (integer->integer-bytes 100000 2 #t) exn:application:mismatch?)
(err/rt-test (integer->integer-bytes 65536 2 #f) exn:application:mismatch?)
(err/rt-test (integer->integer-bytes 32768 2 #t) exn:application:mismatch?)