On 06/27/2012 04:15 PM, Avi Kivity wrote: > On 06/27/2012 01:29 PM, Peter Maydell wrote: >> Add field32() and field64() functions which extract a particular >> bit field from a word and return it. Based on an idea by Jia Liu. >> >> >> +/** >> + * field64 - return a specified bit field from a uint64_t value >> + * @value: The value to extract the bit field from >> + * @start: The lowest bit in the bit field (numbered from 0) >> + * @length: The length of the bit field >> + * >> + * Returns the value of the bit field extracted from the input value. >> + */ >> +static inline uint64_t field64(uint64_t value, int start, int length) >> +{ >> + assert(start >= 0 && start <= 63 && length > 0 && start + length <= 64); >> + return (value >> start) & (~0ULL >> (64 - length)); >> +} >> + > > Undefined for length == 64, so better add that to the assert.
Er, please ignore. It's undefined for length == 0, but that's uninteresting and protected by the assert. -- error compiling committee.c: too many arguments to function