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Source for wiki BlobAPI version 8

author

cowan

comment

ipnr

66.108.19.185

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BlobAPI

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text

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 ''bytevector''divided 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'''

time

2012-04-12 11:57:28