Reuse uint decoders when possible
The int decoder does the same work as its corresponding uint decoder before encoding the integer in Two's complement. We can re-use the uint decoder instead of writing the same code in the corresponding int decoder.
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1 changed files with 20 additions and 30 deletions
50
osc.lisp
50
osc.lisp
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@ -291,16 +291,6 @@
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(ldb (byte 16 0) (decode-int32 s)))
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#-(or sbcl cmucl openmcl allegro) (error "cant decode floats using this implementation"))
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(defun decode-int32 (s)
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"4 byte -> 32 bit int -> two's compliment (in network byte order)"
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(let ((i (+ (ash (elt s 0) 24)
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(ash (elt s 1) 16)
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(ash (elt s 2) 8)
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(elt s 3))))
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(if (>= i #x7fffffff)
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(- 0 (- #x100000000 i))
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i)))
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(defun decode-uint32 (s)
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"4 byte -> 32 bit unsigned int"
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(let ((i (+ (ash (elt s 0) 24)
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@ -309,6 +299,18 @@
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(elt s 3))))
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i))
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(defun decode-uint64 (s)
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"8 byte -> 64 bit unsigned int"
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(let ((i (+ (ash (elt s 0) 56)
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(ash (elt s 1) 48)
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(ash (elt s 2) 40)
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(ash (elt s 3) 32)
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(ash (elt s 4) 24)
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(ash (elt s 5) 16)
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(ash (elt s 6) 8)
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(elt s 7))))
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i))
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(defmacro defint-encoder (num-of-octets &optional docstring)
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(let ((enc-name (intern (format nil "~:@(encode-int~)~D" (* 8 num-of-octets))))
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(buf (gensym))
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@ -327,28 +329,16 @@
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(defint-encoder 4 "Convert an integer into a sequence of 4 bytes in network byte order.")
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(defint-encoder 8 "Convert an integer into a sequence of 8 bytes in network byte order.")
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(defun decode-uint64 (s)
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"8 byte -> 64 bit unsigned int"
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(let ((i (+ (ash (elt s 0) 56)
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(ash (elt s 1) 48)
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(ash (elt s 2) 40)
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(ash (elt s 3) 32)
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(ash (elt s 4) 24)
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(ash (elt s 5) 16)
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(ash (elt s 6) 8)
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(elt s 7))))
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i))
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(defun decode-int32 (s)
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"4 byte -> 32 bit int -> two's complement (in network byte order)"
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(let ((i (decode-uint32 s)))
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(if (>= i #x7fffffff)
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(- 0 (- #x100000000 i))
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i)))
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(defun decode-int64 (s)
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"8 byte -> 64 bit int -> two's compliment (in network byte order)"
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(let ((i (+ (ash (elt s 0) 56)
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(ash (elt s 1) 48)
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(ash (elt s 2) 40)
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(ash (elt s 3) 32)
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(ash (elt s 4) 24)
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(ash (elt s 5) 16)
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(ash (elt s 6) 8)
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(elt s 7))))
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"8 byte -> 64 bit int -> two's complement (in network byte order)"
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(let ((i (decode-uint64 s)))
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(if (>= i #x7fffffffffffffff)
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(- 0 (- #x10000000000000000 i))
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i)))
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