irp value,a,a1,b,b2,c,c3,d,d4,e,e5,f,f6,g,g7,h,h8
        {
           if ~ defined a__
             a__ = 0
           end if
           if a__ = 0
             mov eax,[work.#value]
             a__ = 1
           else
             add [Hashes.#value],eax
             a__ = 0
           end if
        }    

irp value,a,a1,b,b2,c,c3,d,d4,e,e5,f,f6,g,g7,h,h8
        {  common a__ = 0
           forward a__ = a__ + 1
           if a__ mod 2
             add [Hashes.#value],eax
           else
             mov eax,[work.#value]
           end if
        }    

The rept directive is a special kind of macroinstruction (...)
The repetition mechanism applied to rept blocks is the same as the one used to process multiple groups of arguments for macroinstructions, so directives like forward, common and reverse can be used in their usual meaning. (...)
The blocks defined by the irp and irps directives are also processed in the same way as any macroinstructions, so operators and directives specific to macroinstructions may be freely used also in this case.

macro _t [value,value1]
        {
           mov eax,[work.#value]
           add [Hashes.#value1],eax
        }

_t a,a1,b,b2,c,c3,d,d4,e,e5,f,f6,g,g7,h,h8    

macro _t [value*,value1*]