27 lines
666 B
Common Lisp
27 lines
666 B
Common Lisp
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(ql:quickload "flexi-streams")
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(defpackage :mehpng
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(:use :common-lisp :flexi-streams))
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(in-package :mehpng)
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(load "utils.lisp")
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(defmacro hexbytes (&rest bytes)
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(map '(vector flex:octet) (λ (x) (reread "#x" x)) bytes))
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(defparameter signature
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(hexbytes 89 50 4E 47 0D 0A 1A 0A))
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(defgeneric bmatch (obj stream)
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(:documentation "attempt to match OBJ with the binary input stream STREAM.
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returns (VALUES BOOLEAN T)"))
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(defmethod bmatch ((obj vector) stream)
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(values
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(block nil
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(loop for exp across signature
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for got = (read-byte stream nil nil)
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do (unless (and got (= exp got))
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(return)))
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t)
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nil))
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