Function summary | |
---|---|

define-endianess | endian |

define-input-stream | input |

define-output-stream | output |

ieee-float-reader | type |

ieee-float-writer | type |

read-signed-integer | nb-bytes |

read-unsigned-integer | nb-bytes |

string-code | s |

write-signed-integer | number nb-bytes |

write-unsigned-integer | quantity nb-bytes |

Macro summary | |
---|---|

define-ieee-float |
name &key (sign-bits 1) (exponent-bits 8) (mantissa-bits 23) (bias 127) (associated-type
'float) |

with-gensyms |
syms &body body |

Binary bytes reader.

This package provides a binary bytes reader that makes Lisp capable of reading binary encoded numbers, for example with C. It supports both big and little endian numbers.

There are two predefined types that are 'single-float and 'double-float that correspond to the C types. In order to read or write such numbers, you can use either the read-IEEE-single-float, write-IEEE-single-float, read-IEEE-double-float, and write-IEEE-double-float, or get the reader or write corresponding to a given type (previously defined). Let us illustrate this for further clarity.

Example of usage for predefined types, fetching the appropriate functions given a type:

CL-USER> (with-open-file (s "test.bin" :direction :output :element-type '(unsigned-byte 8) :if-exists :supersede) (define-endianess :little-endian) (define-output-stream s) (funcall (IEEE-float-writer 'double-float) 56.3332563322d0)) NIL CL-USER> (with-open-file (s "test.bin" :direction :input :element-type '(unsigned-byte 8)) (define-endianess :little-endian) (define-input-stream s) (funcall (IEEE-float-reader 'double-float))) 56.3332563322d0

Example of new number encoding definition:

(define-IEEE-float IEEE-SANE-extended-float :sign-bits 1 :exponent-bits 15 :mantissa-bits 64 :bias 16383 :associated-type 'long-float)

Then in order to use the newly defined encoding, you can use the first example provided above to read and write (with type 'long-float), or use the newly created functions write-IEEE-SANE-extended-float and read-IEEE-SANE-extended-float:

CL-USER> (with-open-file (s "test.bin" :direction :output :element-type '(unsigned-byte 8) :if-exists :supersede) (define-endianess :little-endian) (define-output-stream s) (write-IEEE-SANE-extended-float 56.3332563322d0)) NIL CL-USER> (with-open-file (s "test.bin" :direction :input :element-type '(unsigned-byte 8)) (define-endianess :little-endian) (define-input-stream s) (read-IEEE-SANE-extended-float)) 56.3332563322d0

compute the ASCII-based numerical value of the string [warning: works only if the chars are coded in ASCII]

read an unsigned integer of nb-bytes bytes from *binary-input-stream*

write an unsigned integer of nb-bytes bytes to *binary-output-stream*

write a signed integer number on nb-bytes to *binary-output-stream*