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Bug 3767 - provide ldexp() as an alternative to scalbn()
Summary: provide ldexp() as an alternative to scalbn()
Status: RESOLVED FIXED
Alias: None
Product: SDL
Classification: Unclassified
Component: *don't know* (show other bugs)
Version: HG 2.0
Hardware: All All
: P2 normal
Assignee: Ryan C. Gordon
QA Contact: Sam Lantinga
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2017-08-21 23:02 UTC by Ozkan Sezer
Modified: 2017-08-29 04:42 UTC (History)
0 users

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Description Ozkan Sezer 2017-08-21 23:02:22 UTC 
The following patch makes SDL_scalbn() to return ldexp(), which is C89,
if scalbn() is not present and FLT_RADIX == 2.

----

SDL_scalbn: return ldexp() if scalbn is not present and FLT_RADIX == 2

diff -r 23000b73ce4e src/stdlib/SDL_stdlib.c
--- a/src/stdlib/SDL_stdlib.c
+++ b/src/stdlib/SDL_stdlib.c
@@ -181,6 +187,10 @@ SDL_scalbn(double x, int n)
     return scalbn(x, n);
 #elif defined(HAVE__SCALB)
     return _scalb(x, n);
+#elif defined(HAVE_LIBC) && defined(HAVE_FLOAT_H) && (FLT_RADIX == 2)
+/* from scalbn(3): If FLT_RADIX equals 2 (which is
+ * usual), then scalbn() is equivalent to ldexp(3). */
+    return ldexp(x, n);
 #else
     return SDL_uclibc_scalbn(x, n);
 #endif /* HAVE_SCALBN */
Comment 1 Ryan C. Gordon 2017-08-29 04:42:35 UTC 
This patch is now https://hg.libsdl.org/SDL/rev/bd5b569b2a1b, thanks!

--ryan.