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Code Issues Releases Activity

Fix an issue introduced in sys/x86/include/endian.h with r232721. In

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that revision, the bswapXX_const() macros were renamed to bswapXX_gen().

Also, bswap64_gen() was implemented as two calls to bswap32(), and
similarly, bswap32_gen() as two calls to bswap16().  This mainly helps
our base gcc to produce more efficient assembly.

However, the arguments are not properly masked, which results in the
wrong value being calculated in some instances.  For example,
bswap32(0x12345678) returns 0x7c563412, and bswap64(0x123456789abcdef0)
returns 0xfcdefc9a7c563412.

Fix this by appropriately masking the arguments to bswap16() in
bswap32_gen(), and to bswap32() in bswap64_gen().  This should also
silence warnings from clang.

Submitted by:	jh
This commit is contained in:
Dimitry Andric 2012-03-29 23:31:48 +00:00
parent 4715a95fb4
commit a80f8859c4
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=233684
1 changed files with 2 additions and 2 deletions
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4
sys/x86/include/endian.h
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@ -65,9 +65,9 @@
#define __bswap16_gen(x) (__uint16_t)((x) << 8 | (x) >> 8)
#define __bswap32_gen(x) \
(((__uint32_t)__bswap16(x) << 16) | __bswap16((x) >> 16))
(((__uint32_t)__bswap16((x) & 0xffff) << 16) | __bswap16((x) >> 16))
#define __bswap64_gen(x) \
(((__uint64_t)__bswap32(x) << 32) | __bswap32((x) >> 32))
(((__uint64_t)__bswap32((x) & 0xffffffff) << 32) | __bswap32((x) >> 32))
#ifdef __GNUCLIKE_BUILTIN_CONSTANT_P
#define __bswap16(x) \