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commit51ea551("make sure byte swapping is optimal for git" 2009-08-18) introduced a "sane definition for ntohl()/htonl()" for use on some GNU C platforms. Unfortunately, for some of these platforms, this results in the introduction of a problem which is essentially the reverse of a problem that commit6e1c234("Fix some warnings (on cygwin) to allow -Werror" 2008-07-3) was intended to fix. In particular, on platforms where the uint32_t type is defined to be unsigned long, the return type of the new ntohl()/htonl() is causing gcc to issue printf format warnings, such as: warning: long unsigned int format, unsigned int arg (arg 3) (nine such warnings, covering six different files). The earlier commit (6e1c234) needed to suppress these same warnings, except that the types were in the opposite direction; namely the format specifier ("%u") was 'unsigned int' and the argument type (ie the return type of ntohl()) was 'long unsigned int' (aka uint32_t). In order to suppress these warnings, the earlier commit used the (C99) PRIu32 format specifier, since the definition of this macro is suitable for use with the uint32_t type on that platform. This worked because the return type of the (original) platform ntohl()/htonl() functions was uint32_t. In order to suppress these warnings, we change the return type of the new byte swapping functions in the compat/bswap.h header file from 'unsigned int' to uint32_t. Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk> Acked-by: Nicolas Pitre <nico@fluxnic.net> Signed-off-by: Jeff King <peff@peff.net>
37 lines
867 B
C
37 lines
867 B
C
/*
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* Let's make sure we always have a sane definition for ntohl()/htonl().
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* Some libraries define those as a function call, just to perform byte
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* shifting, bringing significant overhead to what should be a simple
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* operation.
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*/
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/*
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* Default version that the compiler ought to optimize properly with
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* constant values.
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*/
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static inline uint32_t default_swab32(uint32_t val)
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{
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return (((val & 0xff000000) >> 24) |
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((val & 0x00ff0000) >> 8) |
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((val & 0x0000ff00) << 8) |
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((val & 0x000000ff) << 24));
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}
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#if defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))
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#define bswap32(x) ({ \
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uint32_t __res; \
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if (__builtin_constant_p(x)) { \
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__res = default_swab32(x); \
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} else { \
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__asm__("bswap %0" : "=r" (__res) : "0" (x)); \
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} \
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__res; })
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#undef ntohl
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#undef htonl
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#define ntohl(x) bswap32(x)
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#define htonl(x) bswap32(x)
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#endif
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