This site is a static rendering of the Trac instance that was used by R7RS-WG1 for its work on R7RS-small (PDF), which was ratified in 2013. For more information, see Home. For a version of this page that may be more recent, see BlobAPI in WG2's repo for R7RS-large.

Blob­API

cowan
2012-04-12 11:57:28
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This is a proposal for a WG2 bytevector API. The conceit is that everything is a separate procedure with minimal arguments; this makes for a lot of procedures, but each one can be easily inlined by even a very dumb compiler, providing high efficiency.

Numeric procedures

(bytevector-<type><endian>-ref bytevector n)

Returns a Scheme number corresponding to the binary value encoded according to type beginning at offset n in bytevector. This procedure treats bytevector as potentially containing more than one type.

(<type><endian>vector-ref bytevector n)

Returns a Scheme number corresponding to the binary value encoded according to type beginning at offset n in bytevector, where n is first multiplied by the size of the binary value in bytes. This procedure treats bytevector as a uniformly typed vector.

(bytevector-<type><endian>-set! bytevector n v)

Converts v to a binary value encoded according to type and places it into bytevector beginning at offset n. This procedure treats bytevector as potentially containing more than one type.

(<type><endian>vector-set! bytevector n v)

Converts v to a binary value encoded according to type and places it into bytevector beginning at offset n, where n is first multiplied by the size of the binary value in bytes. This procedure treats bytevector as a uniformly typed vector.

(<type><endian>vector-length bytevector)

Returns a Scheme number corresponding to length of bytevectordivided by the size of the binary value in bytes.

Numeric types

The types are:

u8
unsigned 8-bit integer
s8
signed 8-bit integer
u16
unsigned 16-bit integer
s16
signed 16-bit integer
u32
unsigned 32-bit integer
s32
signed 32-bit integer
u64
unsigned 64-bit integer
s64
signed 64-bit integer
u128
unsigned 128-bit integer
s128
signed 128-bit integer
f32
32-bit float
f64
64-bit float
c64
64-bit complex number (two 32-bit floats, real followed by imaginary)
c128
128-bit complex number (two 64-bit floats, real followed by imaginary)

The endianism values are:

(empty)
Native representations (system-dependent)
le
Little-endian (for float and complex, IEEE format)
be
Big-endian (for float and complex, IEEE format)

Endianism is not applicable to the u8 and s8 types.

String procedures

(bytevector-<encoding>-ref bytevector n l)
Returns a Scheme string corresponding to the binary value encoded according to encoding beginning at offset n in bytevector and continuing for l bytes.
(bytevector-<encoding>-set! blob n v)
Converts v to a binary string encoded according to encoding and places it into bytevector beginning at offset n. Returns the number of bytes encoded.

String encodings

utf8
UTF-8 encoding
utf16
UTF-16 encoding (respects BOM if present, defaults to native encoding otherwise)
utf16be
UTF-16BE encoding (treats BOM as a normal character)
utf16le
UTF-16LE encoding (treats BOM as a normal character)

Equality, map, for-each, fold, unfold

TBD