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Demo of GBITX macros from Plan9 Fcall. These macros allow for extraction of one , two, three, or four bytes from memory address in pointer p. The extracted data is interpreted as unsigned char, unsigned short, unsigned int, or unsigned long int, respectively. This functionality is implemented via compiler preprocessor macros and bit shifts for efficiency.
Prototypes of the said macros are:
uchar GBIT8(uchar*)
ushort GBIT16(uchar*)
ulong GBIT32(uchar*)
vlong GBIT64(uchar*)The definitions are:
#define GBIT8(p) ((p)[0])
#define GBIT16(p) ((p)[0]|((p)[1]<<8))
#define GBIT32(p) ((u32int)((p)[0]|((p)[1]<<8)|((p)[2]<<16)|((p)[3]<<24)))
#define GBIT64(p) ((u32int)((p)[0]|((p)[1]<<8)|((p)[2]<<16)|((p)[3]<<24)) |\
((vlong)((p)[4]|((p)[5]<<8)|((p)[6]<<16)|((p)[7]<<24)) << 32))See also: // See also: https://9fans.github.io/plan9port/man/man3/fcall.html