verbs\va.h macros refactor into templates?

[Sebanisu]

There are a few macros in this file.

APFX

There are 139 usages across 8 files. f is the generated function's name. Could use a c++ using to preserve the name. Tz,Tx,Ty are all types. pfx is a dyadic macro leading to a 2 or more argument function? (x,y) many macros provide their own 3rd arguments. I was thinking that the pfx macro could be replaced with lambdas. pref is a code fragment to be at start. suff is a return argument, aka code fragment to be at end. pref and suff could add complications for template code. You could have an encapsulating function for the pref and suff?

// suff must return the correct result
#define APFX(f, Tz, Tx, Ty, pfx, pref, suff)                                                                     \
    I f(I n, I m, Tx* RESTRICTI x, Ty* RESTRICTI y, Tz* RESTRICTI z, J jt) {                                     \
        Tx u;                                                                                                    \
        Ty v;                                                                                                    \
        pref if (n - 1 == 0) DQ(m, *z++ = pfx(*x, *y); x++; y++;) else if (n - 1 < 0)                            \
          DQ(m, u = *x++; DQC(n, *z++ = pfx(u, *y); y++;)) else DQ(m, v = *y++; DQ(n, *z++ = pfx(*x, v); x++;)); \
        suff                                                                                                     \
    }
//example
APFX(bw0000II, UI,UI,UI, BW0000,, return EVOK;) 

For refactoring just focusing on the loop inside? Working from inside out? Probably would need to port DQ and DQC first those are basically for loops. These are in j.h

#define DQ(n,stm)       {I i=(I)(n)-1;    for(;i>=0;--i){stm}}  // i runs from n-1 downto 0 (fastest when you don't need i)
#define DQC(n,stm)       {I i=-2-(I)(n);    for(;i>=0;--i){stm}}  // i runs from n-1 downto 0 (fastest when you don't need i)

Here's how we could recode DQ and DQC: https://godbolt.org/z/jc3Yzd Possible APFX_impl code: https://godbolt.org/z/jj7srd