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Source for wiki BlobAPI version 10

author

cowan

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ipnr

69.195.59.240

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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>-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>vector-ref` ''bytevector n''`)`

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

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

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

(`<type>vector-length` ''bytevector''`)`

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

(`vector-><type>vector `''vector''`)`

Returns a vector with the same elements as ''<type>vector''.

(`<type>vector->vector `''<type>vector''`)`

Returns a <type>vector with the same elements as ''vector''.  It is an error if an element cannot be accurately converted to `<type>`.

== Numeric types ==

A <type> consists of a <principal type> followed by an <endianism>.

The <principal type> values 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

2012-07-02 11:31:01