Le 29/04/13 00:18, Dmitriy Gorbel a écrit :
Hello, community!
I propose extending the Boost Libraries to provide binary fixed-point arithmetic, within GSOC project.
Fixed-point library will provide nonnegative and negatable class templates for fractional arithmetic, and cardinal and integral for integer arithmetic. In total, four class templates.
Fixed-point arithmetic use more than one notation, and I want to provide several notation to make happy all.
Now I plan to implement two notations - Q notation and notation from C++1y proposal. Examples:
C++1y proposal notation: cardinal<16> 0 <= n < 65536 integral<4> -16 < n < 16 nonnegative<8,-4> 0 <= n < 256 in increments of 2^-4 = 1/16 negatable<16,-8> -65536 < n < 65536 in increments of 2^-8 = 1/256
Q notation: cardinal<16> 0 <= n < 65536 integral<4> -16 < n < 16 nonnegative<8, 4> 0 <= n < 256 has 4 bit for fractional part negatable<16, 8> -65536 < n < 65536 has 8 bit for fractional part
Please, help me to choose default notation, propose other notation, or just make any feedback.
I wonder if we need a default notation. BTW, the choice of the names in the C++1y proposal was a source of conflicts (as always). In my prototype I used fxp_uint and fxp_int fxp_ufract and fxp_fract (fxp_ufreal and fxp_real) Now if you put these classes on a specific namespace for each notation the choice of the default can be deferred without a major impact on the plan. namespace fixed_point { namespace q { } namespace cxx1y {} // if the default is cxx1y notation (a better name is welcome, e.g. rr for range and resolution) using cxx1y::fxp_uint; using cxx1y::fxp_int; ... } With this approach the user could be precise enough fixed_point::q::fxp_fract<8,4>; we could also name the namespace for fixed points fxp and use fxp::q::fract<8,4>; fxp::rr::uinteger<8,4>; Best, Vicente Best, Vicente