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Reuse uint decoders when possible

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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.
This commit is contained in:
Javier Olaechea 2019-03-24 16:14:43 -05:00
parent 5a1eaaebad
commit d130e45f58
1 changed files with 20 additions and 30 deletions
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50
osc.lisp
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@ -291,16 +291,6 @@
(ldb (byte 16 0) (decode-int32 s)))
#-(or sbcl cmucl openmcl allegro) (error "cant decode floats using this implementation"))
(defun decode-int32 (s)
"4 byte -> 32 bit int -> two's compliment (in network byte order)"
(let ((i (+ (ash (elt s 0) 24)
(ash (elt s 1) 16)
(ash (elt s 2) 8)
(elt s 3))))
(if (>= i #x7fffffff)
(- 0 (- #x100000000 i))
i)))
(defun decode-uint32 (s)
"4 byte -> 32 bit unsigned int"
(let ((i (+ (ash (elt s 0) 24)
@ -309,6 +299,18 @@
(elt s 3))))
i))
(defun decode-uint64 (s)
"8 byte -> 64 bit unsigned int"
(let ((i (+ (ash (elt s 0) 56)
(ash (elt s 1) 48)
(ash (elt s 2) 40)
(ash (elt s 3) 32)
(ash (elt s 4) 24)
(ash (elt s 5) 16)
(ash (elt s 6) 8)
(elt s 7))))
i))
(defmacro defint-encoder (num-of-octets &optional docstring)
(let ((enc-name (intern (format nil "~:@(encode-int~)~D" (* 8 num-of-octets))))
(buf (gensym))
@ -327,28 +329,16 @@
(defint-encoder 4 "Convert an integer into a sequence of 4 bytes in network byte order.")
(defint-encoder 8 "Convert an integer into a sequence of 8 bytes in network byte order.")
(defun decode-uint64 (s)
"8 byte -> 64 bit unsigned int"
(let ((i (+ (ash (elt s 0) 56)
(ash (elt s 1) 48)
(ash (elt s 2) 40)
(ash (elt s 3) 32)
(ash (elt s 4) 24)
(ash (elt s 5) 16)
(ash (elt s 6) 8)
(elt s 7))))
i))
(defun decode-int32 (s)
"4 byte -> 32 bit int -> two's complement (in network byte order)"
(let ((i (decode-uint32 s)))
(if (>= i #x7fffffff)
(- 0 (- #x100000000 i))
i)))
(defun decode-int64 (s)
"8 byte -> 64 bit int -> two's compliment (in network byte order)"
(let ((i (+ (ash (elt s 0) 56)
(ash (elt s 1) 48)
(ash (elt s 2) 40)
(ash (elt s 3) 32)
(ash (elt s 4) 24)
(ash (elt s 5) 16)
(ash (elt s 6) 8)
(elt s 7))))
"8 byte -> 64 bit int -> two's complement (in network byte order)"
(let ((i (decode-uint64 s)))
(if (>= i #x7fffffffffffffff)
(- 0 (- #x10000000000000000 i))
i)))