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osc-insert-float32
From: |
Mario Lang |
Subject: |
osc-insert-float32 |
Date: |
Tue, 17 Dec 2019 19:04:11 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) |
Hi.
14 years ago, I wrote this beast to be able to send IEEE floating point
values over the network (Open Sound Control). Reading it today, I am
actually surprised I was driven enough to get this working. I am
wondering, is there a better way to achieve this today?
Maybe something in Emacs itself I missed?
If no, is there a better way to test for negative zero and 0.0e+NaN?
;; From elpa package osc.el
(defun osc-insert-float32 (value)
(let (s (e 0) f)
(cond
((string= (format "%f" value) (format "%f" -0.0))
(setq s 1 f 0))
((string= (format "%f" value) (format "%f" 0.0))
(setq s 0 f 0))
((= value 1.0e+INF)
(setq s 0 e 255 f (1- (expt 2 23))))
((= value -1.0e+INF)
(setq s 1 e 255 f (1- (expt 2 23))))
((string= (format "%f" value) (format "%f" 0.0e+NaN))
(setq s 0 e 255 f 1))
(t
(setq s (if (>= value 0.0)
(progn (setq f value) 0)
(setq f (* -1 value)) 1))
(while (>= (* f (expt 2.0 e)) 2.0) (setq e (1- e)))
(if (= e 0) (while (< (* f (expt 2.0 e)) 1.0) (setq e (1+ e))))
(setq f (round (* (1- (* f (expt 2.0 e))) (expt 2 23)))
e (+ (* -1 e) 127))))
(insert (+ (lsh s 7) (lsh (logand e #XFE) -1))
(+ (lsh (logand e #X01) 7) (lsh (logand f #X7F0000) -16))
(lsh (logand f #XFF00) -8)
(logand f #XFF))))
--
CYa,
⡍⠁⠗⠊⠕
- osc-insert-float32,
Mario Lang <=